After pollination, the pollen grain lands on the stigma and germinates. A pollen tube grows out of the pollen grain, passes down through the style, and reaches the ovary. The male germ cell travels through this pollen tube to reach the ovule, where it fuses with the female germ cell (egg cell) to form a zygote — this process is called fertilisation.

Labelled Diagram:

```
Stigma ← pollen grain germinates here
|
Style ← pollen tube grows through style
|
Ovary ← pollen tube enters ovary
|
Ovule ← male germ cell fuses with egg cell
```

(Students must draw and label: pollen grain on stigma, pollen tube, style, ovary, ovule.)

Source: Chapter 7, Section 7.3.2 — Sexual Reproduction in Flowering Plants

---

• The key process here is pollen tube formation — examiners specifically look for this term.
• Mention all three stages: germination on stigma → pollen tube through style → reaches ovule in ovary.
• The diagram must show the pistil (stigma, style, ovary, ovule) with the pollen tube drawn as a line from the pollen grain down to the ovule. Label all four parts for full marks.
• "Fertilisation" should be named at the end for completeness.

(a) In Amoeba, binary fission can occur in any plane (irregular). In Leishmania, binary fission occurs in a definite plane — always longitudinally — because it has a whip-like flagellum whose position determines the plane of division.

(b) The malarial parasite (Plasmodium) reproduces by multiple fission — the nucleus divides many times and then the cytoplasm divides to form many daughter cells simultaneously.

---

• (a) The key distinction is plane of division: Amoeba — no fixed plane; Leishmania — fixed longitudinal plane due to flagellum. Examinees often lose marks by not mentioning the reason (flagellum) or the plane.
• (b) "Multiple fission" is the exact term needed. The passage (Fig. 7.2 caption) names it for Plasmodium. Writing "binary fission" here is wrong and will cost the mark.

(a) Placenta: Transfers glucose and oxygen from mother's blood to the embryo, and removes waste substances from embryo to mother's blood.

(b) Fallopian tubes: Carry the egg from the ovary to the uterus; fertilisation of the egg by sperm occurs here.

(c) Uterus: Receives and nurtures the embryo; its lining thickens and is richly supplied with blood to nourish the developing embryo.

(d) Ovary: Produces female germ-cells (eggs) and secretes female reproductive hormones.

Source: Chapter 7, Section 7.3.3(b) — Female Reproductive System

---

• The question has four sub-parts worth 2 marks total (~½ mark each), so keep each answer to one concise sentence.
• Examiners look for key function words: transfer nutrition/remove waste (placenta); carry egg/site of fertilisation (fallopian tube); nourish embryo/implantation (uterus); produce eggs/hormones (ovary).
• Avoid repeating the question; go straight to the function. Using terms like "zygote," "implantation," and "villi" where relevant can earn bonus credit.

Puberty is the period during adolescence when reproductive tissues begin to mature and the body undergoes sexual maturation, as the rate of general body growth slows down.

Two changes common to both boys and girls:

1. Growth of thick hair in armpits and the genital area.
2. Skin becomes oily and pimples may develop.

The definition must link puberty to slowing of body growth and maturation of reproductive tissues — not just say "changes occur in teenage years." For the two common changes, stick to those explicitly listed as common to both sexes in the passage (hair growth, oily skin/pimples). Avoid listing breast growth or voice cracking — those are sex-specific. Each point earns ½–1 mark; the definition earns 1 mark.

Reproductive parts of angiosperm: Stamen (male) and Pistil (female).

Location: These are located in the flower.

Structure of Stamen (male reproductive part):
Stamen produces yellowish pollen grains. It consists of two parts:

• Anther – the terminal part that contains and produces pollen grains.
• Filament – the stalk that supports the anther.

Source: Chapter 7, Section 7.3.2 – Sexual Reproduction in Flowering Plants

---

• The question has three parts: name the parts, give their location, and explain the male part's structure. Address all three even in a short answer.
• Examiners expect the two components of stamen (anther + filament) to be named clearly — this is where most marks are earned.
• Do not spend words describing the pistil here; the question specifically asks for the male reproductive part's structure.
• "Yellowish pollen grains" is a good detail from the textbook to include.

Two advantages of vegetative propagation are:

1. Plants raised by vegetative propagation bear flowers and fruits earlier than those produced from seeds.
2. It makes possible the propagation of plants like banana, orange, rose, and jasmine that have lost the capacity to produce seeds. Also, all plants produced are genetically similar to the parent plant, preserving desirable characteristics.

Source: Chapter 7, Section 7.2.5 – Vegetative Propagation

---

The question asks for two advantages, so list exactly two clearly. Examiners look for: (i) early flowering/fruiting, (ii) propagation of seedless plants OR genetic similarity to parent. Any two of these three points earn full marks. Avoid vague answers like "it is easy" — use textbook-specific points.

Reproductive parts: The tiny blob-on-a-stick structures are the reproductive parts of Rhizopus. The blobs are called sporangia, which contain spores. These spores can develop into new Rhizopus individuals.

Non-reproductive parts: The thread-like structures called hyphae are the non-reproductive parts of bread mould.

Source: Chapter 7, Section 7.2.6 – Spore Formation

---

The question directly maps to the textbook passage in 7.2.6. Examiners expect students to use the correct scientific terms: hyphae (non-reproductive) and sporangia/spores (reproductive). A common mistake is calling the whole "blob-on-a-stick" a spore — be precise: the sporangium is the blob (structure), and spores are the cells inside it. Mentioning that spores are covered by thick walls is a bonus but not required for full marks here.

After fertilisation, the embryo is implanted in the uterus wall. The uterine lining becomes thick, spongy, and is richly supplied with blood to nourish the growing embryo. This thickened lining provides the necessary nutrients and oxygen required for the development of the embryo inside the mother's womb.

Source: Chapter 7, Section 7.3.3(b) – Female Reproductive System

---

• The key reason the examiner wants is: to nourish/implant the embryo.
• Mention that the lining is richly supplied with blood — this is a specific textbook detail that fetches marks.
• Avoid confusing this with menstruation (which happens when fertilisation does NOT occur).
• For a 2-mark question, one sentence stating the purpose + one sentence on blood supply is sufficient.

Placenta is extremely essential for foetal development because:

1. Nutrition: The embryo gets glucose and oxygen from the mother's blood through the placenta. Villi on the embryo's side provide a large surface area for this transfer.
2. Waste removal: Waste substances produced by the developing embryo are transferred into the mother's blood through the placenta for disposal.
3. Connection: It is a disc embedded in the uterine wall that links the mother's blood spaces with the embryo's villi, enabling exchange of materials throughout the approximately nine months of development.

Source: Chapter 7, Section 7.3.3(b) – Female Reproductive System

---

Examiners expect two to three distinct functional points about the placenta — nutrition (glucose + oxygen) and waste removal are the two core functions. Mentioning the structural detail (villi, blood spaces, large surface area) earns full marks. Avoid vague statements like "it helps the baby"; use precise terms from the textbook.

Reason: In sexual reproduction, the gametes (sperm and egg) are formed by a special cell division called meiosis, which reduces the number of chromosomes to half (haploid) in each gamete. During fertilisation, the male gamete fuses with the female gamete to form a zygote. This fusion restores the original (diploid) number of chromosomes. Thus, the zygote — and the organism that develops from it — has the same number of chromosomes as the parents.

Example: If a parent cell has 46 chromosomes, each gamete has 23. After fertilisation, the zygote again has 46 chromosomes.

Source: Chapter 7, Section 7.3.1 – Why the Sexual Mode of Reproduction?

---

• The key concept is meiosis → haploid gametes → fertilisation → diploid zygote.
• Examiners expect you to mention: (1) meiosis halves the chromosome number, (2) fertilisation restores it.
• Use the terms haploid, diploid, gametes, zygote, and meiosis — these earn marks.
• Don't just say "chromosomes are maintained" — explain the mechanism (meiosis + fertilisation).

Vegetative propagation is practised for growing only some types of plants due to the following reasons:

1. Lost seed capacity: Some plants like banana, orange, rose, and jasmine have lost the capacity to produce seeds, so they can only be propagated vegetatively.

1. Earlier bearing: Plants raised by vegetative propagation bear flowers and fruits earlier than those grown from seeds.

1. Genetically identical offspring: All plants produced are genetically similar to the parent plant, preserving desirable characteristics.

1. Methods used: Techniques like layering and grafting are used for plants such as sugarcane, roses, and grapes.

Thus, vegetative propagation is useful and necessary for plants that cannot reproduce by seeds or where maintaining parent traits is important.

Source: Chapter 7, Section 7.2.5 – Vegetative Propagation

---

The examiner expects you to give specific reasons with examples (banana, rose, jasmine for lost seed capacity; sugarcane, grapes for agricultural use). Three clear points with examples score full marks. Do not just define vegetative propagation — the question asks why it is practised only for some plants, so focus on advantages and limitations that make it suitable selectively.

Not all multicellular organisms can reproduce through fragmentation or regeneration because of their complex body organisation.

In simple multicellular organisms like Spirogyra or Planaria, the body organisation is relatively simple, so each fragment contains enough information and cell types to grow into a complete individual.

However, in complex multicellular organisms, specialised cells are organised into tissues, tissues into organs, and organs are placed at definite positions in the body. Such a carefully organised body cannot simply divide cell-by-cell into fragments, as each fragment would not have all the necessary tissues and organs to develop into a new individual.

Therefore, complex multicellular organisms require more specialised modes of reproduction involving specific reproductive cell types, rather than simple fragmentation or regeneration.

Source: Chapter 7, Sections 7.2.2 (Fragmentation) and 7.2.3 (Regeneration)

---

• The examiner expects two key ideas: (1) simple multicellular organisms can do it because of simple organisation; (2) complex ones cannot because cells are specialised into tissues and organs in a definite arrangement.
• Mention Spirogyra/Planaria as examples of those that can, to show contrast.
• The phrase "not simply a random collection of cells" from the textbook is the core reasoning — paraphrase it clearly.
• Avoid writing vague answers like "they are complex"; explain why complexity is the barrier.

Fertilization in flowers requires the fusion of the male germ-cell (from pollen grain) with the female germ-cell (egg cell) present in the ovule inside the ovary.

For this to happen, pollen grains must first be transferred from the anther (male reproductive part) to the stigma (female reproductive part) — this process is called pollination.

After pollination, a pollen tube grows out of the pollen grain and travels through the style to reach the ovary, where fertilization takes place.

If pollination does not occur, pollen grains never reach the stigma. Without pollen on the stigma, no pollen tube is formed, and the male germ-cell cannot reach the female germ-cell in the ovule. Therefore, fusion of germ-cells (fertilization) cannot take place, and no zygote, seed, or fruit is formed.

Source: Chapter 7, Section 7.3.2 — Sexual Reproduction in Flowering Plants

---

• Examiners look for a clear cause-and-effect chain: no pollination → no pollen on stigma → no pollen tube → male gamete cannot reach egg cell → no fertilization.
• Mention the key terms: anther, stigma, pollen tube, style, ovule, egg cell, fertilization.
• Do not just state the definition of pollination; you must explain why it is a necessary precondition for fertilization.
• This is typically a 3-mark question; three linked logical steps earn full marks.

The DNA present in the cell nucleus acts as the blueprint for making proteins. During reproduction, DNA copying takes place, but this process is not always perfectly accurate. Slight variations (errors) can occur in the copied DNA.

If the DNA information is changed due to these variations, different proteins will be made by the cell. Since proteins determine the structure and functioning of the body, different proteins will ultimately lead to altered body designs in the offspring.

Thus, inheritance of different (altered) proteins — resulting from changes in DNA — causes changes in body design during reproduction.

Source: Chapter 7, Section 7.1 — Do Organisms Create Exact Copies of Themselves?

---

• The examiner expects you to establish the chain: DNA change → different proteins → altered body design.
• Key terms to include: DNA, information source, proteins, body design.
• The passage directly states: "The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body designs." — quote this logic, not word-for-word, but capture the cause-effect chain.
• This is typically a 2–3 mark reason-based question; keep the answer focused on the three-step logic.

(b) 'Z' only

Only flower Z would develop into a fruit, as fruit formation requires fertilisation, which occurs only when pollen reaches the pistil (stigma). Flower Z, with both functional stamens and pistil, allows pollination and fertilisation, after which the ovary develops into a fruit.

Since the diagram is not visible, the standard reasoning is: a fruit develops only from a flower that has a pistil (ovary) and has undergone fertilisation. Flowers lacking a pistil (male/unisexual) cannot form fruits. The correct option (b) Z only is the given answer, implying only flower Z has a functional pistil with the conditions for fertilisation. Remember: ovary → fruit after fertilisation (Source: Chapter 7, Section 7.3.2).

(d) I, II, III, V, IV

In Leishmania, binary fission occurs in a definite orientation — the flagellum (whip-like structure) divides first, followed by progressive splitting of the cell, making option (d) the correct order.

The diagram shows the flagellum duplicating early in the process and the cell elongating before splitting. The NCERT text emphasises that Leishmania undergoes binary fission in a definite orientation relative to its whip-like structure (flagellum). Examiners expect students to recall that this directional fission distinguishes Leishmania from Amoeba (which splits in any plane). Option (d) matches the standard sequence shown in Figure 7.1(b) of the textbook.

Source: Chapter 7, Section 7.2.1 Fission

(a) The parts of a bisexual flower not directly involved in reproduction are the sepals (calyx) and petals (corolla). They protect the flower and attract pollinators but do not produce gametes.

(b)

| Self-Pollination | Cross-Pollination |
|---|---|
| Transfer of pollen from anther to stigma of the same flower | Transfer of pollen to the stigma of a different flower (same or different plant) |
| No pollinating agent required | Requires agents like wind, water, insects |

Significance of Pollination:

1. It enables fertilisation, leading to seed and fruit formation.
2. Cross-pollination introduces genetic variation, producing better-adapted offspring.

(c) After fertilisation:

• Each ovule develops into a seed (containing the embryo).
• The ovary wall develops into the fruit (pericarp) that encloses the seeds.

Source: Chapter 7 — How do Organisms Reproduce?

---

• (a) Only 1 mark — one crisp line naming sepals and petals is sufficient.
• (b) This is the bulk of the marks (~3). A small table is neat and exam-friendly. Two significance points must be distinct. Avoid vague statements like "helps reproduction."
• (c) Examiners expect the specific fate of both ovule (→ seed) and ovary (→ fruit). Missing either halves the marks here.

(d) Rose, root is the incorrect match. Rose is propagated through stem (cutting/layering), not root.

Source: Chapter 7, Section 7.2.5 Vegetative Propagation

---

The passage states that roses are grown using vegetative propagation methods like layering or grafting, which involve stem cuttings — not roots. Potato propagates via stem (tuber), Bryophyllum via leaf buds, and Money-plant via stem. Examiners expect you to identify the wrong pair directly and give a one-line justification.

(i)

• A – Style (part of pistil connecting stigma to ovary)
• B – Pollen tube (grows down the style carrying male gametes)
• C – Egg cell / Ovule (inside the ovary)

When B reaches C: The pollen tube enters the ovule through the micropyle and releases two male gametes. One fuses with the egg cell to form a zygote (fertilisation); the other fuses with the polar nuclei to form the primary endosperm nucleus (double fertilisation).

Significance: Fertilisation leads to the formation of a zygote, which develops into an embryo, ensuring sexual reproduction and the formation of seeds and new plants.

(ii) Post-fertilisation changes in a flower:

1. The zygote develops into an embryo.
2. The ovule develops into a seed.
3. The ovary develops into a fruit.
4. The sepals, petals, stamens, and style wither and fall off.
5. The wall of the ovary (pericarp) becomes the fruit wall.

Source: Chapter 7, Section 7.3 – How do Organisms Reproduce?

---

• Part (i) is worth ~3 marks: name all three parts (1 mark), explain what happens at fertilisation including double fertilisation (1 mark), and state significance (1 mark).
• Part (ii) is worth ~2 marks: list at least 4–5 post-fertilisation changes concisely. Examiners expect: zygote→embryo, ovule→seed, ovary→fruit, and floral parts withering.
• "Double fertilisation" is a key term examiners reward — don't omit it.
• Keep post-fertilisation changes as a neat list; that format is clear and scores well.

(i) Spores are tiny, microscopic, single-celled reproductive structures produced by organisms like Rhizopus (bread mould). They are formed on sporangia (spore-containing structures) present at the tips of thread-like hyphae.

To overcome unfavourable conditions, spores develop a thick protective coat that resists heat, dryness, and other harsh conditions. When conditions become favourable, each spore germinates and grows into a new individual.

Organism: Rhizopus (bread mould) multiplies using spores.

(ii) Reasons for vegetative propagation:

• Plants that do not produce viable seeds (e.g., banana, rose) can still be propagated.
• It preserves the exact characteristics (traits) of the parent plant, ensuring uniform offspring.

Two methods of vegetative propagation:

1. Cutting – a part of stem/leaf is cut and planted.
2. Layering – a stem branch is bent to the soil and allowed to root before separation.

---

• For (i), examiners expect: definition of spore, location (sporangia), survival mechanism (thick coat), and name of organism — all four points carry marks.
• For (ii), give exactly two reasons and two methods — listing more wastes time and earns no extra marks.
• Common named methods include cutting, layering, grafting, and tissue culture — any two are acceptable.
• Rhizopus is the standard NCERT example for spore formation; mention it by name.

Flow Diagram:

$$\text{Father (44+XY)} \xrightarrow{\text{produces}} \begin{cases} 44+X \text{ (50%)} \\ 44+Y \text{ (50%)} \end{cases}$$

$$\text{Mother (44+XX)} \xrightarrow{\text{produces}} 44+X \text{ (100%)}$$

$$\downarrow$$

$$44+X + 44+X = 44+XX \Rightarrow \textbf{Girl (50\%)}$$
$$44+X + 44+Y = 44+XY \Rightarrow \textbf{Boy (50\%)}$$

Since the father produces two types of sperms (X and Y) in equal numbers, the probability of a male or female child is always 50%. The mother always contributes X chromosome.

Source: Chapter 7, Sexual Reproduction

---

• The key point examiners look for is that sex determination depends on the father's sperm, not the mother's egg (mother always gives X).
• Show clearly that X-sperm → girl, Y-sperm → boy, each with 50% chance.
• The flow diagram is mandatory as the question specifies it — no diagram means losing marks even if the concept is written correctly.
• Use correct chromosome notation (44 autosomes + sex chromosome).

Option A is correct. Both (A) and (R) are true, and (R) is the correct explanation of (A) — since asexual reproduction involves only one parent, the offspring inherit identical DNA, making them genetically similar to the parent.

• The assertion is true: asexual reproduction (fission, budding, spore formation, vegetative propagation) produces genetically identical (or near-identical) offspring.
• The reason is also true and directly explains the assertion: because only one parent is involved, no mixing of genetic material occurs, so offspring inherit the same DNA blueprint.
• Hence (R) correctly explains (A) → Option A.

Option A — Petals and Sepals

Petals attract insects through bright colours and fragrance, while sepals provide protection. Both help in pollination by attracting pollinators.

Source: Sexual Reproduction in Flowering Plants, Chapter 7

The textbook directly asks "What possible functions could the petals and sepals serve?" implying both attract insects/pollinators. Examiners expect you to identify both petals and sepals — not petals alone. Anther and stigma are reproductive parts, not attractants.

(a) All pieces of Planaria A (L, M, and N) and both halves of Planaria B (O and P) can regenerate into complete organisms, as Planaria has the ability to regenerate from any cut piece.

(b) Hydra is another organism that follows the same mode of reproduction (regeneration) as Planaria.

(c) 'Development' in regeneration means that the specialised cells present in the cut piece multiply and form a mass of cells. These cells then differentiate and develop into various cell types and tissues, gradually organising into a complete new organism with all its body parts.

Source: Chapter – How do Organisms Reproduce?, Section – Regeneration

---

• (a) In Planaria, every cut piece can regenerate — examiners expect students to name all pieces (L, M, N, O, P).
• (b) Hydra is the standard textbook example alongside Planaria for regeneration.
• (c) The 2-mark answer must cover two steps: (i) cell multiplication forming a cell mass, and (ii) differentiation/development into a complete organism. Missing either step costs a mark.

Events from fertilisation to foetus:

Sperms travel up the vagina and reach the oviduct (fallopian tube), where fertilisation of the egg occurs, forming a zygote. The zygote starts dividing to form a ball of cells called an embryo. The embryo gets implanted in the thickened, blood-rich lining of the uterus and continues developing, with organs forming, to become a foetus.

Role of Placenta:

The placenta is a disc embedded in the uterine wall. It has villi on the embryo's side surrounded by blood spaces on the mother's side, providing a large surface area for transfer of glucose and oxygen from mother to embryo. It also removes waste substances from the embryo into the mother's blood.

Source: Chapter 7, Section 7.3.3(b)

---

• Examiners expect the sequence: fertilisation → zygote → embryo (cell division) → implantation → foetus.
• For placenta, mention its structure (disc with villi + blood spaces) and both functions: nutrient/oxygen supply AND waste removal. Missing either function loses a mark.
• Use the correct terms: zygote, embryo, foetus, implantation, villi — these are key terminology markers.

During sexual reproduction, germ cells undergo meiosis, producing gametes with half the number of chromosomes. When two gametes combine during fertilisation, the original chromosome number is re-established in the new generation. This maintains the DNA content and body design features of the species, ensuring its stability.

Source: Chapter 7, Section 7.3.1 – Why the Sexual Mode of Reproduction?

---

The examiner expects two key points for 2 marks:

1. Meiosis halves the chromosome/DNA content in germ cells.
2. Fertilisation restores the original DNA content, maintaining species stability.

Avoid writing about variation here — the question is specifically about stability, not variation. Quoting "re-establishment of the number of chromosomes and the DNA content" directly from the textbook is ideal.

(C) Budding — The diagram shows a Hydra with a small bud (protrusion) on its body, which will develop into a new individual. This is budding.

The key visual clue is the small outgrowth (bud) on the Hydra's body. The textbook explicitly states: "Organisms such as Hydra can give out buds which mature into new individuals." Budding is distinct from binary fission (splits into two equal halves), multiple fission (many daughter cells at once), and fragmentation (organism breaks into pieces).

(i) Spore Formation in Rhizopus:

```
Diagram:
● Sporangium (spores inside) ← (a) Reproductive part
|
| Sporangiophore
|
─────────────────────────────── Mycelium (hyphae) ← (b) Non-reproductive part
|
Rhizoids
```

(a) Reproductive parts: Sporangium (containing spores)
(b) Non-reproductive parts: Mycelium (hyphae), rhizoids, sporangiophore

Rhizopus requires moisture to germinate and grow. A dry bread slice lacks the necessary moisture/water, so spores cannot germinate and Rhizopus cannot multiply on it.

---

(ii) Budding in Hydra:

The process of reproduction in Hydra is called Budding.

In Hydra, a small outgrowth called a bud develops on the side of the parent's body. Cells divide rapidly at that spot, causing the bud to grow. The bud gradually develops a mouth and tentacles. Once fully formed, it detaches from the parent body and grows into a new, independent Hydra.

This is a type of asexual reproduction.

• The diagram must clearly label the sporangium (reproductive) and hyphae/mycelium (non-reproductive). Examiners award 1 mark for a neat, labelled diagram.
• The dry bread reason must mention lack of moisture — this is the key term.
• For Hydra: state the name budding, describe the outgrowth formation, development of tentacles, and separation — these are the scoring steps.
• "Asexual reproduction" at the end reinforces understanding and can fetch the clinching mark.

(i) Three contraceptive techniques and their side effects:

1. Condoms – Barrier method used by males/females. Side effect: slight reduction in sensitivity; may tear or fail if not used correctly.
2. Oral pills – Contain hormones that prevent egg release. Side effect: may cause nausea, irregular bleeding, or hormonal imbalance with long-term use.
3. Copper-T (IUD) – Placed in the uterus to prevent implantation. Side effect: may cause heavy bleeding, cramping, or uterine discomfort.

(ii)

(a) Fertilisation takes place: The fertilised egg (zygote) implants in the uterine wall. The uterus lining is maintained to nourish the developing embryo, and pregnancy begins. Menstruation does not occur.

(b) Egg is not fertilised: The egg and the thickened uterine lining (built up to receive a zygote) are shed. This shedding of the lining along with blood is called menstruation.

Source: Chapter 7 – Reproduction, Section 7.3 Sexual Reproduction

---

• Part (i) is worth ~3 marks: name each method + one side effect each — exactly what is needed.
• Part (ii) is worth ~2 marks: one point each for (a) and (b). The key idea in (b) is why menstruation occurs — the uterus lining is shed because fertilisation did not happen.
• Examiners look for: correct name of method, a valid side effect (not vague), and the link between fertilisation/non-fertilisation and uterine lining behaviour.
• "Copper-T" and "oral pills" are the textbook terms — use them exactly.

(d) Plasmodium

Plasmodium (the malarial parasite) divides into many daughter cells simultaneously through multiple fission.

The passage explicitly states: "Other single-celled organisms, such as the malarial parasite, Plasmodium, divide into many daughter cells simultaneously by multiple fission." Yeast reproduces by budding; Leishmania and Amoeba undergo binary fission. Examiners expect students to distinguish between binary fission, multiple fission, and budding.

(b) (ii) and (iv)

Statement (ii) is correct — sex depends on what the child inherits from the father (X or Y chromosome). Statement (iv) is correct — sex is determined at fertilisation when gametes fuse.

Source: Chapter 8, Section 8.2.4 Sex Determination

---

• Statement (i) is wrong: all children inherit X from the mother, so the mother does not determine sex.
• Statement (iii) is wrong: the passage clearly states half the children will be boys and half will be girls — equal probability.
• Statements (ii) and (iv) are directly supported by the text: the father's gamete (X or Y) decides sex, and this is fixed at fertilisation.

(a)

(i) Production of eggs — Ovaries

(ii) Site of fertilisation — Fallopian tube (oviduct)

(iii) Site of implantation — Uterus (uterine lining)

(iv) Entry of sperms — Vagina

(b)

(i) After implantation of zygote:
The uterus prepares itself to receive and nurture the growing embryo. Its lining thickens and becomes richly supplied with blood to nourish the embryo. A special tissue called placenta develops, which is embedded in the uterine wall. It allows glucose and oxygen to pass from mother to embryo and waste substances to be removed.

(ii) If the egg is not fertilised:
The thickened uterine lining is no longer needed. It slowly breaks down and sheds along with blood vessels. This shedding is called menstruation, which occurs approximately every 28 days.

Source: Chapter 7, Section 7.3.3(b) — Female Reproductive System

---

• Part (a) is straight recall — 1 mark per point, so one word/phrase each is enough.
• Part (b)(i) expects mention of: lining thickening, blood supply, and placenta — these are the three key ideas examiners look for.
• Part (b)(ii) should clearly state that the lining breaks down and is shed as menstruation (the word "menstruation" must appear).
• Do not confuse site of fertilisation (fallopian tube) with site of implantation (uterus) — this is a very common exam error.

(a) Puberty is the period during adolescence when the reproductive tissues begin to mature and the body shows sexual maturation. It marks the transition from childhood to sexual maturity.

Two changes in boys at puberty:

• Thick hair growth on the face; voice begins to crack.
• The penis occasionally becomes erect; new hair appears in armpits and genital area.

(b) The testes are located outside the abdominal cavity in the scrotum because sperm formation requires a lower temperature than the normal body temperature. The scrotum provides this cooler environment necessary for spermatogenesis.

(c) Three techniques of contraception:

1. Mechanical barrier – condom (male) or vaginal covering (female)
2. Oral contraceptive pills – change hormonal balance to prevent egg release
3. Copper-T / loop – placed in the uterus to prevent pregnancy

Oral contraceptive pills are not meant for males; they are taken by females.

Source: Chapter 7 – Reproduction in Human Beings, Sections 7.3.3(a) and 7.3.3(d)

---

• (a) Puberty definition must mention "adolescence" and "sexual maturation/reproductive tissue maturation." Pick two distinct changes specific to boys (not common ones like underarm hair).
• (b) The one-line reason — lower temperature than body temperature — is the exact textbook phrasing; examiners expect it verbatim.
• (c) Name three methods from different categories. The question specifically asks which is not for males — oral pills (hormonal pills) are the safest answer here, as condoms and vasectomy are male methods; copper-T and pills are female. Avoid naming vasectomy/tubectomy as one of the three unless you also answer the sub-part correctly.

Sexually reproducing organisms use DNA copying mechanisms to maintain species stability. During reproduction, the DNA is copied using chemical reactions and passed to offspring. Although copying is not 100% accurate and small variations arise, the consistency of DNA copying ensures that body design features are preserved, maintaining stable populations suited to their ecological niche.

The examiner expects two key points: (1) DNA copying ensures inheritance of body design features, and (2) the consistency (not perfection) of this copying maintains population stability. Avoid writing only about variation — the question focuses on stability. The phrase "consistency of DNA copying" directly from the chapter is important to include.

Source: Chapter 7, Section 7.1 and 7.1.1

(C) P-3, Q-4, R-1, S-2

Leishmania – Binary Fission (3); Spirogyra – Fragmentation (4); Planaria – Regeneration (1); Plasmodium – Multiple Fission (2).

• Leishmania: Binary fission in a definite orientation (it has a whip-like flagellum at one end).
• Spirogyra: Fragmentation – breaks into pieces upon maturation, each growing into a new individual.
• Planaria: Regeneration – a classic example; cut pieces regrow into whole organisms.
• Plasmodium: Multiple fission – divides into many daughter cells simultaneously (malarial parasite).

Examiners commonly set this type of matching MCQ; knowing which organism uses which specific mode is essential.

(a) Fertilisation is the fusion of the male germ-cell (from pollen grain) with the female germ-cell (egg cell) present in the ovule, resulting in the formation of a zygote.

(b) After fertilisation:

• Zygote → divides repeatedly to form an embryo inside the ovule.
• Ovule → develops a tough coat and becomes a seed.
• Ovary → grows rapidly and ripens to form a fruit.
• Stamens (along with petals, sepals, style, and stigma) → shrivel and fall off.

Source: Chapter 7, Section 7.3.2 – Sexual Reproduction in Flowering Plants

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• (a) is 1 mark — one clear sentence defining fertilisation as fusion of germ-cells to form a zygote is sufficient.
• (b) is 2 marks — examiners expect all four structures listed. Present them as bullet points for clarity; this avoids missing any. Use the exact textbook terms: embryo, seed, fruit, fall off.
• A common mistake is writing only zygote → embryo and ignoring ovule → seed or ovary → fruit. All four changes must be stated to score full marks.

(a) The testes are located outside the abdominal cavity in the scrotum because sperm formation requires a temperature slightly lower than normal body temperature. The scrotum provides this cooler environment, which is essential for the production of viable germ cells (sperms).

(b) The seminal vesicles and prostate gland secrete fluids that provide nutrition to the sperms and make the medium alkaline, which facilitates their transport and motility. This ensures that the sperms remain active and functional while travelling towards the egg.

• For (a), the key point is temperature — testes need ~2°C below body temperature for sperm production. Examiners expect this specific reason.
• For (b), name the glands (seminal vesicles, prostate), state their functions: nutrition + alkaline medium. These points come from the reproductive system topic; though not detailed in the given passage, this is standard CBSE textbook content for this chapter.

Option (B): Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

The Assertion is correct. The Reason is also true — placenta is indeed a disc embedded in the uterine wall — but it merely describes the structure of the placenta, not how it provides nutrition to the embryo.

• The A is directly from the textbook: "The embryo gets nutrition from the mother's blood with the help of a special tissue called placenta."
• The R is also textbook-accurate: "This is a disc which is embedded in the uterine wall."
• However, R explains the location/structure of the placenta, not the mechanism of nutrition transfer (villi, blood spaces, large surface area). So R does not explain A — hence option (B).

The correct answer is (C) Fragmentation and regeneration.

Spirogyra reproduces by fragmentation (breaks into pieces that grow into new individuals), and Planaria reproduces by regeneration.

The textbook (Chapter 7) explicitly states that Spirogyra "simply breaks up into smaller pieces upon maturation" — this is fragmentation. Planaria is the classic example of regeneration (cut pieces regrow into complete organisms). Students often confuse the two; remember: fragmentation = organism breaks apart naturally; regeneration = lost/cut parts regrow. Option C is the only one with this correct order.

(i)
(a) Vas deferens — carries sperm
(b) Testes — production of male gametes
(c) Seminal vesicles and prostate gland — secretion makes transport of sperms easier
(d) Scrotum — provides suitable temperature for sperm formation

(ii) Two characteristics of sperms:

• Sperms are microscopic and motile (have a tail for movement).
• They carry genetic information (half the chromosomes) from the male parent.

(iii) Surgical contraceptive methods involve blocking the reproductive ducts by surgery — vasectomy (blocking vas deferens in males) and tubectomy (blocking fallopian tubes in females). This prevents the sperm/egg from reaching the site of fertilisation.

Side effect: If surgery is not performed properly, it can cause infections and other complications. Also, such methods may be misused for illegal sex-selective abortions, threatening the female-male sex ratio.

Source: Chapter 7, Section 7.3.3(d) — Reproductive Health

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• Part (i) tests direct recall of the male reproductive system; examiner expects the correct organ name for each function — do not write explanations, just the organ.
• Part (ii): any two logical, distinct characteristics earn full marks; motility and genetic material are safest choices.
• Part (iii): name both surgeries (vasectomy/tubectomy), state what is blocked, then give the textbook side effect — infection due to improper surgery is the exact point the textbook mentions. Mention of sex-selective misuse adds completeness for a 2-mark part.

(i) Regeneration:
Regeneration is the process by which an organism can re-grow a complete individual from its cut or broken body parts. Organisms like Planaria can regenerate — if cut into pieces, each piece grows into a complete new organism.

Organism that does not show regeneration: A dog (or any complex multicellular organism).
Reason: In complex organisms, cells are highly specialised and organised into tissues and organs placed at definite positions in the body. Such a highly organised system cannot simply regenerate from an isolated cell or body part.

(ii) The dark green filamentous structures are Spirogyra. It reproduces by fragmentation.

Process: Upon maturation, the Spirogyra filament simply breaks up into smaller pieces or fragments. Each fragment then grows and develops into a new complete Spirogyra filament. This occurs because Spirogyra has a simple body organisation where each fragment retains the capacity to grow into a new individual.

Source: Chapter 7 — How do Organisms Reproduce?, Section 7.2.2 Fragmentation

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• (i) Examiners expect: definition of regeneration, a correct example (Planaria/Hydra), a correct non-example (complex animal), and the reason (specialised/organised tissues/organs).
• (ii) Activity 7.4 in the textbook directly identifies these as Spirogyra filaments. The method is fragmentation — state it by name, then explain the process briefly. Don't confuse fragmentation with fission.
• Keep answers concise — one short paragraph per sub-question is ideal at this marks level.

(a) anther

The stamen is the male reproductive part of a bisexual flower. It produces pollen grains in the anther, which contain the male gametes.

Source: Sexual Reproduction in Flowering Plants, Chapter 7

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• The anther is the top part of the stamen where pollen grains (containing male germ-cells) are produced and stored.
• The ovary contains ovules/egg cells (female gametes); the stigma is where pollen lands; the filament is just the stalk supporting the anther — none of these contain male gametes.
• This is directly supported by the passage: "Stamen is the male reproductive part and it produces pollen grains." The anther is the pollen-bearing part of the stamen.

(c) seeds

Plants like rose and banana have lost the capacity to produce seeds, so they are propagated vegetatively.

Source: Vegetative Propagation, Chapter 7

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The passage explicitly states: "such methods also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds." This is a direct recall question — just identify the correct word from that line. Do not confuse with flowers or fruits, which these plants still produce normally.

(a) Leishmania undergoes binary fission in a definite orientation (along its length). It causes kala-azar (leishmaniasis).

(b) Two advantages of vegetative propagation:

1. Plants produced are genetically identical to the parent (desirable traits are preserved).
2. Plants bear fruits/flowers earlier than those grown from seeds.

(c) (Standard 2-mark internal choice — answer the chosen option):

Regeneration: Some organisms like Hydra and Planaria can regenerate a whole new individual from cut body parts. Specialised cells proliferate and develop into different cell types and tissues. This is possible because of the high degree of organised cell differentiation in these organisms.

Source: Chapter – How do Organisms Reproduce?, Asexual Reproduction section

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• (a): Examiners expect both the organism name (Leishmania) and the disease (kala-azar) for the 1 mark.
• (b): Two distinct advantages needed — genetic fidelity and faster/earlier fruit-bearing are the standard NCERT points.
• (c): Since no specific internal choice was printed, regeneration is used as a representative 2-mark concept. In the actual exam, read your choice carefully and write ~40 words covering definition + example + how it works.
• Answers are grounded in NCERT Class 10 Science, Ch. 8.

(a) Uterus — Contraceptive devices like loop or copper-T are placed in the uterus to prevent pregnancy.

(b) Fallopian tube (Oviduct) — It is blocked (tubectomy) to prevent the transfer of eggs from ovary to uterus.

(c) Ovaries — The female germ cells (ova) are formed in the ovaries.

(d) Placenta — The embryo receives nutrition from the mother's blood through the placenta, embedded in the uterine wall.

Source: Chapter 7, Section 7.3.3(b) — Female Reproductive System

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• This is a 2-mark question with 4 sub-parts, so each part carries ~½ mark — one word/line per part is sufficient.
• Examiners expect the correct organ name; a brief qualifier shows understanding and avoids confusion.
• Key terms to remember: uterus (copper-T), fallopian tube/oviduct (blocked), ovaries (ova formation), placenta (nutrition transfer).
• Do not confuse ovary (egg formation) with uterus (embryo development); this is a common error.

In humans, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). The mother can only pass on an X chromosome to every child. The father, however, can pass either X or Y. A child inheriting X from the father is a girl; inheriting Y makes a boy. Hence, the sex of the child is determined by the father.

Source: Chapter 8, Section 8.2.4 – Sex Determination

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The key logic examiners want: mother is always XX → only X possible from her → father's contribution (X or Y) is the deciding factor. State this clearly with the XX/XY notation. Two marks = two key points: (1) mother contributes only X, (2) father contributes either X or Y, determining the sex. Don't forget to mention which combination gives a girl (XX) and which gives a boy (XY).

Two contraceptive methods:

1. Mechanical barrier (Condom): A covering placed on the penis (or inside the vagina) that prevents sperm from reaching the egg, thus avoiding fertilisation. It also helps prevent sexually transmitted diseases.

1. Hormonal pills: Oral pills that change the hormonal balance of the body so that eggs are not released, preventing fertilisation. However, they may cause side effects.

Source: Chapter 7, Section 7.3.3 – Reproductive Health

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• This is a 2-mark question, so name two methods and give a brief explanation of each (one line each).
• The textbook lists several methods (barrier, hormonal pills, copper-T, surgical); pick any two and explain the mechanism (how they prevent pregnancy).
• Examiners award ½ mark for naming and ½ mark for explaining each method — so never just list names without explanation.
• Avoid writing only surgical methods, as those need slightly more detail; barrier + hormonal is the safest combination for a 2-mark answer.

(a) Functions:

(i) Testis — Produces male germ cells (sperms) and the hormone testosterone.

(ii) Scrotum — Provides a lower temperature environment necessary for sperm formation.

(iii) Vas deferens — Carries sperms from the testis to the urethra for transfer during mating.

(iv) Prostate gland — Secretes fluids that make the semen nutritive and provide a medium for sperm motility.

(b)
(i) Motile germ cell — Sperm (male germ cell)
(ii) Germ cell that stores food — Egg/Ovum (female germ cell)

Source: Chapter 7, Section 7.3.3

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• Part (a) carries ~2 marks (½ mark each function) and part (b) carries ~1 mark (½ each).
• Keep each function to one crisp line — examiners deduct for vague answers like "helps in reproduction."
• For (b), the key contrast is: sperm is motile (has a tail/flagellum) while the egg is non-motile but large and rich in stored food (yolk). This distinction is a common exam point.

Planaria reproduces by regeneration. Planaria has a simple body organisation with specialised cells that can proliferate and develop into all body parts, allowing each cut piece to grow into a complete organism.

Spirogyra, however, reproduces by fragmentation, not regeneration.

Another example: Hydra can also reproduce by regeneration.

Source: How do Organisms Reproduce?, Section 7.2.3 Regeneration

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• The question tests whether students can distinguish between fragmentation (Spirogyra) and regeneration (Planaria) — two different processes often confused.
• Key reason to mention: Planaria has specialised cells that proliferate and undergo organised development, making regeneration possible.
• Hydra is the go-to textbook example for the "other organism" — it is explicitly mentioned alongside Planaria in the regeneration section.
• Do not say Spirogyra reproduces by regeneration — the passage clearly states Spirogyra uses fragmentation (breaking into pieces upon maturation).

(a) Hibiscus has a higher possibility of self-pollination, as it is a bisexual (perfect) flower with both stamens and pistil present in the same flower.

(b) The two reproductive parts of a bisexual flower are:

1. Stamen (male reproductive part – produces pollen)
2. Pistil/Carpel (female reproductive part – contains ovules)

• For (a): Mustard, Papaya, and Watermelon have separate male and female flowers or plants (unisexual), making cross-pollination more likely. Hibiscus is bisexual (has both stamens and pistil), so self-pollination is possible.
• For (b): Examiners expect the correct botanical terms — stamen and pistil (or carpel). Avoid vague terms like "male part" without naming them.

(a) The sex of a newborn is determined by the type of sex chromosome inherited from the father. If the child inherits an X chromosome from the father, it is a girl (XX); if it inherits a Y chromosome, it is a boy (XY).

(b) In males, the two sex chromosomes are X and Y, which are not perfectly homologous — they differ in size and genetic content. Hence, they are called a mismatched pair.

(c) During gamete formation (meiosis), the chromosome number is halved — each gamete carries only one set (haploid, n). When the male gamete (n) fuses with the female gamete (n) during fertilisation, the original diploid number (2n) is restored in the progeny.

Source: Heredity and Evolution, Sex Determination / Chromosomes and Sex

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• (a) Examiners want mention of the father's contribution (X or Y) and the resulting XX/XY combination.
• (b) Key phrase is "mismatched" — X and Y differ in size and gene content; one mark for stating this clearly.
• (c) This is a 2-mark answer: name meiosis (halving) + fertilisation (restoration). Both steps must be mentioned for full credit.

(i)

(1) Leaves of Bryophyllum on soil: Buds present on the leaf margins develop into new plants. Mode: Vegetative propagation.

(2) Planaria cut into many pieces: Each piece regenerates and grows into a complete new organism. Mode: Regeneration.

(3) Rhizopus sporangia liberate spores: The spores germinate under favourable conditions of moisture and warmth to grow into new Rhizopus organisms. Mode: Spore formation.

(ii) Changes after fertilisation in a flower:

• The zygote develops into an embryo.
• Ovules develop into seeds.
• The ovary develops into a fruit.
• Petals, sepals, stamens, style, and stigma wither and fall off.
• The wall of the ovary becomes the fruit wall (pericarp).

Source: Chapter 7 – How do Organisms Reproduce?, Sections 7.2 and 7.3

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• For part (i), examiners expect both: what happens + name of the mode. Naming the mode correctly fetches the mark.
• Bryophyllum = vegetative propagation (not budding); Planaria = regeneration; Rhizopus = spore formation — these three must not be confused.
• For part (ii), the key changes are ovule→seed, ovary→fruit, and the withering of other floral parts. These are standard board-exam points and must be listed clearly.

(i) Testes are located outside the abdominal cavity in a pouch called the scrotum, because sperm formation requires a temperature slightly lower than body temperature.

Two functions of testes:

1. Production of sperms (male germ cells).
2. Secretion of the male hormone testosterone.

(ii)

1. If the egg is fertilised: The zygote divides and forms an embryo, which implants in the thickened uterine lining. The lining is maintained to nourish the embryo; pregnancy continues for approximately nine months.

1. If the egg is not fertilised: The uterine lining breaks down and sheds along with blood vessels. This causes menstruation, which lasts for a few days.

(iii) In males, the vas deferens is blocked/cut surgically (vasectomy) to prevent sperm transfer. In females, the fallopian tube is blocked/cut surgically (tubectomy) to prevent the egg from reaching the uterus. In both cases, fertilisation cannot occur.

Source: Chapter 7 — How do Organisms Reproduce?, Section 7.3.3

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• (i): Examiners expect the reason for scrotal location (temperature) and both functions — sperm production AND testosterone secretion. Missing either costs marks.
• (ii): Two distinct scenarios must be addressed separately. Key terms: zygote → embryo → implantation for (1); menstruation/shedding of uterine lining for (2).
• (iii): Name the specific structure blocked in each sex and state the outcome (fertilisation prevented). "Vasectomy/Tubectomy" as terms are acceptable but not mandatory for CBSE Class 10.

(d) Syphilis and Warts

Bacterial infections caused by unsafe sex include gonorrhoea and syphilis; viral infections include warts and HIV-AIDS.

Source: Reproductive Health, Section 7.3.3(d), Chapter 7

The passage clearly states: "bacterial infections such as gonorrhoea and syphilis, and viral infections such as warts and HIV-AIDS." So the bacterial example is syphilis and the viral example is warts — matching option (d). Students often confuse HIV-AIDS (viral) with bacterial infections; remember the category each belongs to.

(i) Two modes of asexual reproduction in Hydra:

1. Budding: In Hydra, a bud develops as an outgrowth due to repeated cell division at one specific site. The bud gradually develops into a tiny individual and, when fully mature, detaches from the parent body to become a new independent organism.

2. Regeneration: If a Hydra is broken into pieces, each piece can regenerate into a complete new individual using specialised regenerative cells.

(ii) Vegetative Propagation:

It is a mode of asexual reproduction in which parts like roots, stems, or leaves of a plant develop into new plants under suitable conditions.

Two advantages:

• Plants raised by vegetative propagation bear flowers and fruits earlier than those grown from seeds.
• All plants produced are genetically identical to the parent, retaining all its desirable characteristics.

Source: Chapter 7, Sections 7.2.4 and 7.2.5

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• The question is 5 marks: allocate roughly 2 marks to (i) and 3 marks to (ii).
• For (i), examiners expect both budding and regeneration named and briefly explained — Hydra's "What you have learnt" summary confirms both modes.
• For (ii), define vegetative propagation first, then list exactly two advantages from the textbook passage (early flowering/fruiting; genetic similarity). Don't add extra points — it wastes time and gains nothing.
• Always name and explain in budding answers; just naming alone may cost you a mark.

(d) halving of chromosomes at the time of gamete formation.

Meiosis halves the chromosome number in gametes; when two gametes fuse at fertilisation, the original chromosome number is restored in the offspring.

The source passage (7.3.1) explicitly states that germ-cells are formed by meiosis, which results in half the number of chromosomes. Fusion of two such gametes (fertilisation) restores the full chromosome number in the zygote — keeping it constant across generations. Options (a), (b), and (c) describe incorrect stages or incorrect processes.

(b) Transpiration : creates a suction force which pulls water inside the plant.

The diagram shows water vapour escaping from leaves through stomata — this is transpiration. Its key significance is that it creates a suction (transpiration pull) that draws water upward from roots through xylem. Options (a), (c), and (d) are incorrect as evaporation is a physical process, excretion refers to waste removal, and translocation involves transport of food, not water vapour loss.

(a) In Leishmania, binary fission occurs in a definite orientation (longitudinal). In Plasmodium, multiple fission (schizogony) occurs.

(b) Sexual reproduction introduces variation in offspring due to combination of genetic material from two parents, which helps in evolution and better adaptability.

(c)
(i) Yeast cells require sugar (glucose) as a nutrient source for energy to carry out budding. Plain water provides no nutrients, so yeast cannot multiply in it.

(ii) Rhizopus (bread mould) requires moisture for spore germination and growth. A dry bread slice lacks sufficient water, so Rhizopus cannot grow on it.

Source: Chapter – How do Organisms Reproduce?, Asexual Reproduction section

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• (a): Examiners expect students to distinguish between the two organisms — Leishmania = binary fission (longitudinal), Plasmodium = multiple fission.
• (b): The key phrase is "variation" leading to adaptability/evolution — this is the standard NCERT-expected answer.
• (c)(i) & (ii): Both answers hinge on conditions needed for reproduction — nutrients for yeast and moisture for Rhizopus. Mentioning the specific missing condition is essential for full marks.

(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

The bacteria are almost similar (not identical) because of small inaccuracies in DNA copying — so R actually does explain A, making (a) the correct choice.

> Answer: (a)

Both A and R are true, and R is the correct explanation of A. DNA copying involves small inaccuracies, so the resulting cells are similar but not identical — hence "almost similar," not exactly identical.

• The passage states: "the DNA copies generated will be similar, but may not be identical… the surviving cells are similar to, but subtly different from each other" — this is caused by inaccuracies in DNA copying.
• Since the inaccuracy in DNA copying directly explains why bacteria are only almost similar (not exactly identical), R correctly explains A.
• Examiners expect students to link the cause (inaccurate DNA copying) to the effect (cells being almost similar, not identical). Option (a) is correct.

(d) Watermelon and Papaya

Papaya and watermelon bear unisexual flowers (containing either stamens or pistil, not both), while mustard and Hibiscus bear bisexual flowers.

Source: Chapter 7, Section 7.3.2 — Sexual Reproduction in Flowering Plants

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The textbook explicitly states: "The flower may be unisexual (papaya, watermelon)… or bisexual (Hibiscus, mustard)." So any option containing mustard or Hibiscus refers to bisexual flowers. Only option (d) lists both unisexual examples. Remember: unisexual = one reproductive organ; bisexual = both stamens and pistil.

I notice that sub-question (c) is incomplete — options (i) and (ii) are not provided. I will answer (a) and (b) fully, and note the gap for (c).

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(a) In self-pollination, pollen is transferred from the anther to the stigma of the same flower or same plant. In cross-pollination, pollen is transferred from the anther of one flower to the stigma of a different plant of the same species.

(b) The petals (corolla) attract insects for pollination through their bright colours and fragrance. After fertilisation, the petals wither and fall off, as their role in attracting pollinators is complete.

(c) (Sub-question (c) cannot be answered as options (i) and (ii) were not provided in the question. Please include the missing options for a complete answer.)

Source: Life Processes / How do Organisms Reproduce, Sexual Reproduction in Plants

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• (a) The key distinction examiners look for is same plant vs. different plant. One crisp line is enough for 1 mark.
• (b) Two parts = two marks: name the part (petals) and state what happens after fertilisation (they wither/fall). Missing either half loses the mark.
• (c) Always check that all options of a choice-based sub-question are copied into your paper before the exam — here the options were cut off. In the actual exam, attempt whichever option you choose and write it clearly as (c)(i) or (c)(ii).

Plasmodium undergoes multiple fission — the nucleus divides repeatedly, forming many daughter nuclei, and then the cytoplasm splits simultaneously to produce many daughter cells at once.

Leishmania undergoes binary fission — the cell splits into two equal halves, but in a definite orientation (longitudinal, in relation to its whip-like structure).

Source: Chapter 7, Section 7.2.1 – Fission

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The key distinction the examiner wants is:

• Plasmodium → multiple fission (one cell → many cells at once)
• Leishmania → binary fission in a definite plane (because of its whip-like flagellum)

Don't confuse Leishmania with Amoeba — Amoeba also does binary fission but in any plane. Leishmania's fission is directional. Mentioning the whip-like structure earns a mark.

(A) (i) and (ii)

Rapid spread of bread mould is due to formation of large number of spores and presence of moisture and nutrients in bread, which provide ideal conditions for spore germination and growth.

The textbook states that spores are produced in sporangia and can develop into new Rhizopus individuals. Spores begin to grow when they contact a moist surface (moisture + nutrients in bread). Low temperature slows growth; hyphae are non-reproductive structures — so (iii) and (iv) are incorrect. Examiners expect students to distinguish reproductive structures (sporangia/spores) from non-reproductive ones (hyphae).

(C) It has a very small surface area for glucose and oxygen to pass from mother to the embryo.

The passage clearly states the placenta "provides a large surface area for glucose and oxygen to pass from the mother to the embryo." Option C falsely says "very small surface area," making it the incorrect statement. All other options are directly supported by the text.

(a)

Budding in Hydra:

In Hydra, a small outgrowth called a bud develops on the parent body due to repeated cell division. The bud gradually grows, develops a mouth and tentacles, and eventually detaches to become a new independent Hydra.

Diagram:

```
Tentacles
|||
[Parent Hydra]
|
[Bud] ← developing bud with tentacles
|
[Base]
```
(Label: Parent Hydra, Bud, Tentacles, Point of detachment)

The cells used for reproduction in this process are undifferentiated meristematic-type cells (generalised cells capable of growth and proliferation) that form the bud.

Source: Chapter 7, Section 7.2 — Modes of Reproduction Used by Single Organisms

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• Diagram is compulsory — even a rough, clearly labelled sketch earns marks. Label at minimum: Parent Hydra, Bud, Tentacles, Point of detachment.
• The process description should cover: outgrowth → cell division → development of mouth & tentacles → detachment.
• For the cell type, the textbook refers to cells capable of "growing, proliferating and making other cell types" — examiners accept undifferentiated cells or interstitial cells. Do not leave this part out; it is specifically asked and carries a mark.
• Keep the answer concise but complete — diagram + process + cell name = 3 marks.

Variations in DNA copies created during reproduction help a species survive environmental changes.

Example: A population of bacteria lives in temperate water. Due to global warming, the water temperature rises sharply. Most bacteria die, but a few heat-resistant variants survive and reproduce. Thus, variation ensures the species is not completely wiped out.

Source: Chapter 7, Section 7.1.1 – The Importance of Variation

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• The examiner expects: (1) a clear statement linking variation to survival, and (2) the specific textbook example of bacteria surviving temperature increase due to heat-resistant variants.
• Do not use a different example — the bacteria/global warming example is directly from the textbook and is the safest choice.
• The key phrase to include: "variation is useful for the survival of species over time."
• Avoid padding; two tight points earn full marks here.

Option C — 46

A human zygote is formed by fusion of a sperm (23 chromosomes) and an egg (23 chromosomes), giving the zygote 46 chromosomes.

Each human gamete (sperm/egg) is haploid — it carries 23 chromosomes. Fertilisation combines two gametes, restoring the diploid number of 46. Option A (23) is the gamete number; Option D (92) would be if a zygote fused again; Option B (44) is incorrect. Examiners expect you to recall that human body cells have 46 chromosomes, so the zygote must also have 46.

A — Cotyledon

The cotyledon stores food and provides nourishment to the embryo during germination of the seed.

Source: How Do Organisms Reproduce, Chapter 7

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The cotyledon (seed leaf) is the food-storing part of the seed. During germination, the embryo (radicle → root; plumule → shoot) draws nutrition from the cotyledon until the seedling can photosynthesize. Radicle and plumule are parts of the embryo that grow into root and shoot respectively — they are not food sources. "Embryo" is too broad and is the developing plant, not the food reserve.

Option A — Sugarcane, roses, grapes.

These plants are specifically mentioned as examples grown by vegetative propagation for agricultural purposes.

Source: Chapter 7, Section 7.2.5 Vegetative Propagation

The passage explicitly states: "methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes." Mustard reproduces by seeds (sexual reproduction), so any option containing mustard is incorrect. Potato shows vegetative propagation too (Activity 7.5), but it is not listed in the main text alongside sugarcane and roses — Option A directly matches the textbook's wording.

(i) The diagram shows asexual reproduction — specifically various modes such as fission, budding, and fragmentation.

(ii) The unicellular organism shown in the diagram is Amoeba (which reproduces by binary fission).

(iii) Two advantages of asexual reproduction over sexual reproduction:

1. Only one parent is required, so the organism does not need a mate.
2. It is a rapid process, allowing quick multiplication of individuals.

(iv) Budding in Hydra:
Hydra reproduces asexually by budding. In this process, a small outgrowth called a bud develops on the body of the parent Hydra. The bud gradually grows, develops a mouth and tentacles, and eventually detaches from the parent body to grow into a new independent Hydra.

Source: Chapter 7, Section 7.2 (Asexual Reproduction)

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• (i) The diagram collectively shows asexual reproduction; name the broader term and mention examples visible.
• (ii) Amoeba is the classic unicellular example from the textbook (Section 7.2.1); Leishmania/Plasmodium are also unicellular but Amoeba is the primary diagram shown.
• (iii) This is only 1 mark for two points — keep it brief (one line each). Examiners look for "no mate needed" and "rapid reproduction."
• (iv) 2 marks = name the mode + explain it in 2–3 sentences. Mention: bud formation → growth → detachment → new organism. The word budding must appear for full credit.

(i) X – Stigma (female reproductive part / pistil)
Y – Anther (part of stamen / male reproductive part)

(ii) The yellowish coloured structures produced by part Y (anther) are pollen grains.

(iii) The process by which pollen grains are transferred from the anther (Y) to the stigma (X) is called Pollination.

(iv) After pollination, the pollen grain on the stigma grows a pollen tube which travels through the style to reach the ovary. The male germ-cell from the pollen fuses with the egg cell (female gamete) in the ovule — this is called fertilisation, forming a zygote.

The zygote divides several times to form an embryo inside the ovule. The ovule develops a tough coat and becomes a seed. The ovary grows and ripens to form a fruit. Under suitable conditions, the seed germinates and develops into a new plant.

Source: Chapter 7, Section 7.3.2 – Sexual Reproduction in Flowering Plants

---

• For (i), from the diagram context and the passage: stamen produces pollen (yellow) → anther is part Y; stigma is the terminal sticky part of pistil → part X.
• For (ii), the passage explicitly states "it produces pollen grains that are yellowish in colour."
• For (iii), the term "pollination" is the exact term to use; mention self/cross only if marks demand it.
• For (iv) (2 marks ≈ 40–50 words): cover pollen tube growth → fertilisation → zygote → embryo → ovule becomes seed → ovary becomes fruit. These are the key sequential steps examiners look for. Do not omit "fertilisation" or "zygote" — they are scoring terms.

(B) Hibiscus and mustard

Bisexual flowers contain both stamens and pistil. Hibiscus and mustard are bisexual, while papaya and watermelon are unisexual.

The passage explicitly states: "the flower may be unisexual (papaya, watermelon)… or bisexual (Hibiscus, mustard)." Any option containing papaya or watermelon is incorrect. Only option (B) lists two bisexual flowers.

(D) a-(iii), b-(ii), c-(i), d-(iv)

From the passage: fertilisation occurs in the oviduct (iii); embryo implants in the uterus (ii); sperms enter through the vagina (i); waste from the embryo is removed via the placenta (iv). Option D matches all four correctly.

(a) The site of fertilization in the human female is the fallopian tube (oviduct).

(b) The uterus prepares itself by developing a thick and spongy lining richly supplied with blood vessels. This lining nourishes the embryo and provides it with oxygen and nutrients for development.

(c)(i) If the egg is not fertilized, it lives for about one day. The uterus lining, which was prepared to receive the embryo, is no longer needed. The lining slowly breaks down and is shed along with the unfertilized egg in the form of blood and mucus through the vagina. This is called menstruation, which lasts for about 2–8 days.

Source: Chapter – How do Organisms Reproduce?, Section – Reproduction in Human Beings

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• (a) One line is enough — "oviduct/fallopian tube" is the key term.
• (b) Focus on the uterine lining becoming thick and blood-vessel-rich; that's the examiner's expected detail.
• (c)(i) The 2-mark answer must cover two points: (i) the egg is not fertilised and degenerates, and (ii) the uterine lining breaks down → menstruation. Mentioning the term menstruation is essential for full marks.

Steps to culture yeast in the laboratory:

1. Dissolve about 10 g of sugar in 100 mL of water.
2. Take 20 mL of this solution in a test tube and add a pinch of yeast granules to it.
3. Plug the mouth with cotton and keep in a warm place for 1–2 hours.
4. Place a drop of the culture on a slide, cover with a coverslip, and observe under a microscope.

Source: Chapter 7, Activity 7.1

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Examiners expect the four sequential steps from Activity 7.1 — sugar solution preparation, adding yeast, incubation in a warm place, and microscopic observation. Writing them as a numbered list is ideal for a 2-mark answer. Avoid adding extra biology; just reproduce the activity steps concisely.

(i) Seed coat – Protects the embryo inside the seed from damage, desiccation, and unfavourable conditions.

(ii) Cotyledon – Stores food (nutrients) that provides nourishment to the embryo during germination.

(iii) Radicle – Develops into the root system of the new plant.

(iv) Plumule – Develops into the shoot (stem and leaves) of the new plant.

This question asks for one function each — so one crisp line per part is sufficient. The seed parts (radicle → root, plumule → shoot, cotyledon → food storage, seed coat → protection) are standard NCERT content tested frequently. Avoid writing lengthy definitions; the examiner awards marks for correctly matching each part to its function.

(C) Ovary and testis both

This halving of chromosomes occurs during meiosis, which takes place in the reproductive organs — ovary (in females) and testis (in males) — to form gametes.

The question refers to meiosis (reduction division), where chromosome number is halved (from diploid to haploid). It occurs only in gonads (ovary and testis) during gamete formation, not in all body cells (which undergo mitosis). Options A and B are incomplete — both organs are involved, making C the correct answer.

(B) Vegetative buds produced in the notches of the leaf

The textbook (Section 7.2.5) explicitly states that buds produced in the notches along the leaf margin of Bryophyllum fall on the soil and develop into new plants. This is vegetative propagation. Eliminate other options: apical buds, flowers, and fruits are not involved in this process.

(i) Self-Pollination vs Cross-Pollination:

| Self-Pollination | Cross-Pollination |
|---|---|
| Transfer of pollen from anther to stigma of the same flower or same plant. | Transfer of pollen from anther to stigma of a different flower on a different plant of the same species. |
| No pollinating agent required. | Requires agents like wind, water, insects, etc. |

(ii) Identification of A, B, C (Longitudinal Section of a Flower):

Based on a standard diagram of a flower's reproductive parts:

• A – Stigma: It is the top part of the pistil. Function: It receives pollen grains during pollination (sticky surface traps pollen).

• B – Style: It is the elongated stalk connecting stigma to the ovary. Function: It provides a passage for the pollen tube to grow down towards the ovary.

• C – Ovary: It is the swollen base of the pistil containing ovules. Function: It contains ovules which, after fertilisation, develop into seeds; the ovary develops into fruit.

---

• For (i), examiners expect a clear point-by-point or tabular comparison — at least 2 differences for 2 marks.
• For (ii), since the actual diagram is not visible, A/B/C are identified as the three standard parts of the pistil (stigma, style, ovary) — the most commonly labelled structure in CBSE Chapter 7 diagrams on sexual reproduction in plants. Each part must be named + one function stated for full marks (1 mark per part). If your diagram labels different structures (e.g., anther, filament, petal), apply the same format: name + one function each.

(i) Functions of parts of the female reproductive system:

(I) Ovary: Produces female germ cells (eggs/ova) and secretes female sex hormones.

(II) Fallopian tube (Oviduct): Carries the egg from the ovary to the uterus. Fertilisation of the egg by sperm takes place here.

(III) Uterus: Receives and nurtures the fertilised egg (embryo). Its lining thickens every month to prepare for implantation. It provides nourishment to the developing embryo through the placenta and its muscles contract during childbirth.

---

(ii) Two contraceptive methods used by human males:

1. Condom: A mechanical barrier worn over the penis during intercourse; prevents sperm from reaching the egg and also protects against sexually transmitted diseases.

1. Vasectomy: A surgical method in which the vas deferens is blocked or cut, preventing the transfer of sperms, thus avoiding fertilisation.

Source: How do Organisms Reproduce?, Section 7.3.3(b) and 7.3.3(d)

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• For (i), each part carries 1 mark — state the function clearly in one sentence each; mention both egg production and hormone production for ovary to be safe.
• For (ii), name the method AND briefly state how it works — examiners look for the mechanism, not just the name.
• Vasectomy (blocking vas deferens) and condom are the two standard male methods mentioned in the NCERT text; stick to these.

Stages of Budding in Hydra:

```
Stage 1 Stage 2 Stage 3
Hydra Bud growing Bud detaches
| |
[Parent] [Parent] [Parent] [New Hydra]
| + Bud (separate individual)
```

1. Stage 1: A small outgrowth (bud) appears on the parent Hydra due to repeated cell division.
2. Stage 2: The bud grows and develops tentacles, becoming a tiny individual.
3. Stage 3: The fully mature bud detaches from the parent body and becomes a new independent individual.

(Labelled diagram should show: Parent Hydra, Bud, Tentacles, Detached new Hydra)

Source: Chapter 7, Section 7.2.4 Budding

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• This question is diagram-based, so drawing is mandatory — describe what to label if drawing on paper.
• Three stages must be shown: bud initiation → bud development with tentacles → detachment.
• Key labels: Parent body, Bud, Tentacles, Detached Hydra.
• Examiners award 1 mark for correct stages and 1 mark for proper labels. Do not omit labels.

(C) (i) and (iii)

A bisexual flower contains both stamen and pistil (i), and since it has both parts, it can undergo self-pollination or cross-pollination (iii).

• Statement (i) is directly from the textbook: "bisexual (Hibiscus, mustard) when it contains both stamens and pistil."
• Statement (iii) is correct because possessing both male and female parts makes self-pollination possible, and cross-pollination is always an option for any flower.
• Statement (ii) describes a unisexual flower — a common distractor.
• Statement (iv) is wrong — a bisexual flower can produce fruits on its own through self-pollination and fertilisation.

(i) The diagram shows Multiple Fission, a type of Asexual Reproduction.

(ii) In stage P, the nucleus of the cell (enclosed in a protective cyst) divides repeatedly by mitosis to form many daughter nuclei. Each daughter nucleus then gets surrounded by cytoplasm, eventually forming multiple daughter cells (spores) within the cyst wall. When conditions become favourable, the cyst breaks open and daughter cells are released.

(iii) Plasmodium (malarial parasite) reproduces by multiple fission.

(iv) Tissue Culture is the method used to raise plants that have lost the capacity to produce seeds (e.g., banana, orange, rose, jasmine).

Two advantages:

• Many plants can be grown from a single parent in disease-free conditions.
• All plants produced are genetically similar to the parent, preserving desirable characteristics.

Source: Chapter 7 — Vegetative Propagation (7.2.5), Spore Formation (7.2.6)

---

• Multiple fission vs. binary fission: In binary fission the nucleus divides once giving 2 daughter cells; in multiple fission the nucleus divides many times first (while enclosed in a cyst), giving many daughter cells simultaneously. Examiners expect this distinction.
• Stage P specifically refers to the repeated nuclear division phase inside the cyst — mention "cyst," "repeated nuclear division," and "daughter cells/spores" for full marks.
• Plasmodium is the textbook example of multiple fission (Exercise Q1 confirms Amoeba → binary fission; Yeast → budding).
• For part (iv), the textbook explicitly names tissue culture for plants like banana, orange, rose, jasmine that have lost seed capacity — use these exact examples if needed. The two advantages must come from the passage (disease-free + genetically similar to parent).

(i) The diagram shows spore formation in Rhizopus (bread mould). The blob-on-a-stick structures are sporangia containing spores. This is a method of asexual reproduction.

(ii)

• Advantage: Spores are covered by thick walls, protecting them under unfavourable conditions; they can grow rapidly when conditions become suitable.
• Disadvantage: No genetic variation is produced, so the population may be wiped out if environmental conditions change drastically.

(iii) In asexual reproduction, a new individual is created from a single parent through DNA copying. Since only one organism is involved and no mixing of genetic material occurs, all offspring are genetically identical to the parent, resulting in no variation.

(iv) Despite its complexity, sexual reproduction produces genetic variations by combining DNA from two individuals. These variations help the species adapt to changing environments and ensure long-term survival of the population.

Source: Chapter 7 — Reproduction, Sections 7.2.6, 7.1.1, 7.3

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• The diagram almost certainly shows Rhizopus spore formation (the classic asexual reproduction diagram in the NCERT chapter). Name it correctly.
• For part (ii), examiners expect one advantage and one disadvantage — keep each to one sentence.
• For part (iii), the key phrase is "single parent + DNA copying = identical offspring = no variation." Mention all three links.
• For part (iv), the core answer from the textbook is: sexual reproduction allows greater variation, aiding species survival — state this clearly. Avoid vague answers like "it is better."

(i) Two non-surgical contraceptive methods Radha can use:

1. Mechanical barrier method – Use of condom (on penis) or similar covering worn in the vagina, which prevents sperm from reaching the egg.
2. Hormonal pills (oral pills) – These change the hormonal balance of the body so that eggs are not released and fertilisation cannot occur.

(She could also use copper-T / loop placed in the uterus to prevent pregnancy.)

(ii) Surgical methods to prevent pregnancy:

• Vasectomy – The vas deferens in the male is blocked, preventing sperm transfer.
• Tubectomy – The fallopian tube in the female is blocked, preventing the egg from reaching the uterus.

In both cases, fertilisation does not take place.

(iii) Examples of sexually transmitted diseases (STDs):

• Caused by bacteria: Gonorrhoea / Syphilis
• Caused by virus: HIV-AIDS / Warts

Source: Chapter 7, Section 7.3.3(d)

---

• For part (i), name two methods clearly — barrier (condom/vaginal covering), hormonal pills, or copper-T/loop are all valid; pick any two.
• For part (ii), examiners expect the specific names vasectomy and tubectomy along with a one-line explanation of each.
• For part (iii), the passage directly names gonorrhoea and syphilis (bacterial) and warts and HIV-AIDS (viral) — use these exact examples for full marks.
• Avoid writing more than needed; crisp, labelled points score well in 5-mark questions.

(i) The organ responsible for the formation of male germ cells (sperms) is the testes. The condition that favours sperm formation is a lower temperature than the normal body temperature. That is why the testes are located outside the abdominal cavity in the scrotum.

(ii) Pathway followed by male germ cells to reach the site of fertilisation:

Testes → Vas deferens → Urethra → Penis → Vagina → Oviduct (Fallopian tube)

Along the vas deferens, glands like the prostate and seminal vesicles add secretions that form semen, providing nutrition and ease of transport to the sperms.

(iii) The male germ cell (sperm) has a long tail which helps it move towards the female germ cell. The sperm mainly consists of genetic material and this long tail.

Source: Chapter 7, Section 7.3.3 (a) Male Reproductive System

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• Part (i) — Examiners expect both the organ name (testes) and the specific condition (lower temperature). Missing the condition loses a mark.
• Part (ii) — The pathway is a standard 2-mark question. Write it as a flow chart/arrow diagram. Mentioning the glands (prostate, seminal vesicles) adds completeness and secures full marks.
• Part (iii) — The answer must be the long tail — avoid vague answers like "it can swim." The textbook uses the exact phrase "long tail that helps them to move towards the female germ-cell."

(C) Asexual reproduction by breaking up of Spirogyra filaments into smaller parts

The passage explicitly states: "Spirogyra simply breaks up into smaller pieces upon maturation. These pieces or fragments grow into new individuals." This is fragmentation — an asexual method. Options A and B are incorrect descriptions; Option D describes sexual reproduction with meiosis, which is not mentioned for Spirogyra here.

(i) Sugarcane reproduces through vegetative propagation (a type of asexual reproduction). New plants are grown from stem cuttings (nodes) of the parent plant.

(ii) Two advantages of vegetative propagation:

• All offspring are genetically identical to the parent, preserving desirable traits.
• Plants can be grown without seeds and mature faster than seed-grown plants.

(iii) Two more examples of plants reproducing by vegetative propagation:

• Rose (stem cuttings)
• Potato (tubers/eyes)

(iv) Regeneration is not possible in all animals because many multicellular animals have cells organised into specialised tissues and organs, placed at definite positions in the body. Simple cell-by-cell division is impractical in such complex body organisations. Only simpler organisms like Planaria, which have less specialised organisation, can regenerate.

Source: Chapter 7, Section 7.2.2 Fragmentation / Modes of Reproduction

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• (i) Examiners expect the term "vegetative propagation" — just saying "asexual" alone is incomplete.
• (ii) The two most credited advantages are genetic uniformity/preservation of traits and faster/seedless growth.
• (iii) Any two valid examples with the plant part used scores full marks. Rose, potato, ginger, banana, bryophyllum are all acceptable.
• (iv) The key idea from the textbook is: specialised cells form tissues → tissues form organs → organs occupy definite positions → cell-by-cell division becomes impractical. Always connect complexity of body organisation to inability to regenerate.

(i) Post-fertilization changes:

(a) Zygote: The zygote undergoes repeated mitotic divisions to form an embryo (ball of cells), which eventually develops into a seed (embryo enclosed within seed coat).

(b) Ovule: The ovule develops into a seed after fertilization. It contains the embryo and stored food.

(c) Ovary: The ovary develops into a fruit. Its wall (pericarp) thickens to form the fruit wall surrounding the seed(s).

(d) Sepals: The sepals wither and fall off (dry up and drop) after fertilization, as they are no longer needed to protect the flower.

(ii) Germination:

Germination is the process by which a seed sprouts and develops into a new seedling under suitable conditions of water, warmth, and air. The embryo within the seed resumes growth and emerges as a young plant.

---

• For part (i), examiners expect one clear, distinct change per structure — avoid mixing them up.
• Remember: zygote → embryo → seed; ovule → seed; ovary → fruit; sepals → wither/fall.
• For germination, a one-sentence definition mentioning the seed and conditions (water, warmth, air) is sufficient for 1 mark.
• The source passages focus mainly on animal reproduction; flower post-fertilization changes are standard NCERT Chapter 7 content — use textbook terminology precisely.

(C) Uterus

The fertilised egg (zygote) travels to the uterus, where it is implanted in the uterine lining, which thickens and is richly supplied with blood to nourish the growing embryo.

Source: Chapter 7, Section 7.3.3(b) — Female Reproductive System

The key fact: fertilisation occurs in the oviduct (fallopian tube), but implantation occurs in the uterus. Examiners often test this distinction. Do not confuse the two locations. Options A (oviduct) is where fertilisation happens, not implantation.

(i) When spores are liberated from the sporangia (blob-like structures) of bread mould, they disperse into the environment. Upon landing on a moist surface with suitable nutrients, the thick-walled spores germinate and grow into new Rhizopus individuals.

(ii) The leaves of Bryophyllum have buds in their margins. When they fall on wet soil, these buds develop and grow into new plants. This is an example of vegetative propagation.

(iii) Fertilisation will not occur. Pollen from a totally unrelated species is incompatible with the stigma, so the pollen tube will not develop properly and the egg cell will remain unfertilised.

(iv) Copper-T prevents implantation of the fertilised egg in the uterus. It also releases copper ions that are toxic to sperms, thus acting as a contraceptive and preventing pregnancy.

(v) When Spirogyra breaks into smaller fragments upon maturation, each fragment grows into a new individual. This mode of asexual reproduction is called fragmentation.

Source: Chapter 7 — How do Organisms Reproduce?, Sections 7.2.2 (Fragmentation), 7.2.6 (Spore Formation)

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• Each part carries 1 mark, so one crisp point per answer is sufficient.
• (i) Key idea: thick-walled spores germinate on moist surfaces → new Rhizopus.
• (ii) Examiners expect the term vegetative propagation and mention of marginal buds.
• (iii) The textbook implies cross-species pollination is incompatible — fertilisation does not occur. State this clearly.
• (iv) Two actions of Copper-T: prevents implantation + copper ions are spermicidal. Either point earns the mark.
• (v) Name the process — fragmentation — and link it to growth of each fragment into a new individual.

(i) Most bacteria would die due to the sudden rise in temperature. However, a few heat-resistant variants would survive and reproduce, gradually forming a new population adapted to warmer temperatures. This shows how variation helps species survive environmental changes.

(ii) The sperm fertilises the egg in the fallopian tube (oviduct), forming a zygote. The zygote divides and moves to the uterus, where it implants and develops into an embryo, eventually leading to pregnancy.

(iii) Since only pistil is present (no stamen/anther), self-pollination cannot occur. Cross-pollination by external agents (wind, insects) becomes necessary for fertilisation to take place.

(iv) If the egg is not fertilised, the uterine lining (which had thickened to receive the embryo) breaks down and sheds along with blood vessels. This is called menstruation.

(v) The seed germinates under appropriate conditions of water and air. The embryo inside the seed grows, breaking open the seed coat, and develops into a new seedling — this process is called germination.

Source: Chapter 7 — Reproduction, Sections 7.1.1, 7.3, What You Have Learnt

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• Each sub-part targets a different concept: variation/survival, fertilisation, cross-pollination, menstruation, and germination.
• For (i), the key phrase from the text is "the few variants resistant to heat would survive and grow further."
• For (ii) and (iv), remember fertilisation occurs in the fallopian tube, not the uterus.
• For (iv), menstruation is directly caused by the egg not being fertilised — examiners specifically look for this reasoning.
• Keep each point concise; one to two sentences per situation is enough for the marks allotted.

Diagram:

```
Stigma ← pollen grain lands here
|
Style
|
Ovary
(contains ovule with egg cell)

Pollen tube grows from pollen grain → travels through style → reaches ovary
```

(Draw a neat labelled diagram showing a pistil with a pollen grain on stigma, pollen tube growing down through the style into the ovary.)

(a) The part that receives the pollen grain is the Stigma (the sticky terminal part of the pistil).

(b) The Pollen tube grows out of the pollen grain and travels through the style to carry the male germ cell to the female germ cell in the ovary.

Source: Chapter 7, Section 7.3.2 — Sexual Reproduction in Flowering Plants

---

• The diagram must show: pollen grain on stigma → pollen tube → style → ovary. Label only the two asked parts: Stigma and Pollen tube.
• (a) Stigma is the correct term; do not write "style" or "pistil."
• (b) Pollen tube is the key term here — it is not the pollen grain itself that moves, but a tube that grows out of it.
• Since it's 2 marks, one mark each for correctly naming and labelling the two parts (the diagram supports both). Keep the diagram simple but neat.

| Basis | Pollination | Fertilisation |
|---|---|---|
| Definition | Transfer of pollen grains from anther to stigma | Fusion of male germ-cell with female gamete (egg cell) in the ovule |
| Nature | External process; may involve agents like wind, water, or animals | Internal process occurring inside the ovary |

Examiners expect two clear, contrasting points. The most scoring approach is a small table or two labelled points. Key distinction: pollination is transfer (external), fertilisation is fusion (internal). Avoid vague language — use textbook terms: anther, stigma, male germ-cell, ovule, zygote.

Source: Chapter 7, Section 7.3.2 — Sexual Reproduction in Flowering Plants

Option D — they reproduce asexually.

Spirogyra reproduces by fragmentation, Leishmania by binary fission, and Hydra by budding — all asexual methods. Also, Leishmania is unicellular while Spirogyra and Hydra are multicellular, so options B and C are incorrect.

The question tests whether students can find the one common trait shared by all three organisms. Sexual reproduction is ruled out (all three examples in the chapter illustrate asexual reproduction). Options B and C are wrong because Leishmania is unicellular while Spirogyra and Hydra are multicellular. Option D is the only universally correct statement. Examiners award the mark for choosing D with a brief justification.

Option D: Binary Fission

The diagram shows an Amoeba dividing into two equal daughter cells — this is binary fission, a type of asexual reproduction where a single cell splits into two identical cells.

The key visual clue is the nucleus elongating and dividing, followed by the cell constricting into two equal halves — the defining feature of binary fission. Budding produces an unequal outgrowth; fragmentation breaks a multicellular organism; spore formation involves sporangia. The NCERT summary confirms: "In fission, many bacteria and protozoa simply divide into two or more daughter cells." Amoeba is the classic example of binary fission.

Vegetative propagation is advantageous because plants bear flowers and fruits earlier than seed-grown plants, and it allows propagation of plants like banana and rose that have lost the capacity to produce seeds.

Source: Chapter 7, Section 7.2.5 – Vegetative Propagation

---

For a 1-mark answer, pick one or two key advantages directly from the textbook. Examiners expect:

• Earlier flowering/fruiting, or
• Propagation of seedless plants (banana, orange, rose, jasmine), or
• Offspring genetically similar to parent.

Any one well-stated reason earns full marks. Avoid listing all points — that wastes time in a board exam.

Prenatal sex determination is banned in India because it leads to sex-selective abortion of female foetuses (female foeticide), causing the female-male sex ratio to decline at an alarming rate, which is harmful to society.

Source: Chapter 7, Section 7.3.3(d) – Reproductive Health

The passage directly states that prenatal sex determination has been prohibited by law because people misuse it to abort female foetuses (sex-selective abortion), leading to a declining child sex ratio. Examiners expect you to mention: (1) misuse for sex-selective/female foeticide, and (2) declining sex ratio. Both points together make the complete 1-mark answer.

(C) Assertion (A) is true, but Reason (R) is false.

Asexual reproduction produces fewer variations, but DNA copies generated by replication are similar to the original (not different), though minor errors may occur.

• A is true: The textbook states variations are limited in asexual reproduction since only one individual is involved.
• R is false: The passage clearly says "the DNA copies generated will be similar, but may not be identical" — they are largely similar, not dissimilar. So R incorrectly states the copied DNA is "not similar" to the original.
• Since R is false, option (C) is correct.

(C) Formation of fruit

Since 'P' labels the pistil (female reproductive part), removing it prevents fertilisation, and thus the ovary cannot develop into a fruit.

Source: Sexual Reproduction in Flowering Plants, Chapter 7, Section 7.3.2

---

The figure shows 'P' pointing to the pistil (centre of the flower). The pistil contains the ovary, which after fertilisation develops into the fruit (and the ovule into the seed). Without the pistil, pollens can still form (from stamens), the flower already exists, and seeds cannot form either — but the direct consequence most clearly linked to removing the pistil is no fruit formation, which is the standard expected answer. Note: formation of pollen (option A) depends on the stamen, not the pistil, so that is unaffected.