The processes which together perform the maintenance job in living organisms are called life processes.

Source: Chapter 5, Section 5.1 – What are Life Processes?

This is a direct fill-in-the-blank from the definition in the textbook. The exact term "life processes" must be written. No elaboration is needed for 1 mark.

Answer: C — Reproduction

Reproduction is not a life process, as stated in Chapter 7: it is not necessary to maintain the life of an individual organism, unlike nutrition, respiration, and excretion.

The key passage is from Chapter 7's introduction, which explicitly states that "reproduction is not necessary to maintain the life of an individual organism, unlike the essential life processes such as nutrition, respiration, or excretion." Chapter 5 lists the core life processes as nutrition, respiration, transport, and excretion. Reproduction is studied separately because it is about continuation of the species, not individual survival. Examiners expect students to recall this distinction directly.

The process is called nutrition. It transfers food (source of energy) from outside the body to the inside of the organism.

Source: Chapter 5, Section 5.1 – What are Life Processes?

The passage directly states: "there must be a process to transfer a source of energy from outside the body of the organism, which we call food, to the inside, a process we commonly call nutrition." Examiners expect the exact term nutrition as the answer. No further elaboration is needed for 1 mark.

Invisible molecular movement is necessary for life because living organisms are highly organised structures that constantly break down due to environmental effects. To prevent this breakdown and maintain order, organisms must continuously repair their structures. Since all structures are made of molecules, molecules must be moved around constantly to keep the organism alive.

Source: Chapter 5, Introduction

The examiner wants two key points: (1) living structures naturally tend to break down (lose order) due to the environment, and (2) molecular movement is needed to repair and maintain that organisation. The virus example is a useful supporting detail but not essential for 2 marks. Stick to cause-and-effect logic — breakdown of order → death, so molecules must move to prevent it.

Viruses show no molecular movement until they infect a cell, and since molecular movement is considered essential for life, it is debated whether viruses are truly alive.

Source: Chapter 5, Introduction

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The examiner expects you to directly link no molecular movement in viruses to the definition of life. The key concept is that molecular movement is necessary for maintaining living structures, and viruses lack this until they infect a host cell. Avoid vague answers like "they don't eat or breathe" — be specific about molecular movement.

In multicellular organisms like humans, all cells are not in direct contact with the surrounding environment. As body size increases and body design becomes more complex, simple diffusion cannot supply oxygen to all the cells. Therefore, a specialised transport system is needed to carry oxygen from one place to all parts of the body.

Source: Chapter 5, Section 5.1 — What are Life Processes?

The examiner expects two linked points: (1) cells are not in contact with the environment in large/complex organisms, and (2) diffusion is too slow/limited to reach all cells — hence a transport system is required. Avoid over-explaining; two clear sentences earn full marks. The answer must come from Section 5.1 of the textbook.

Organisms that use simple inorganic sources like carbon dioxide and water for nutrition are called autotrophs.

The passage directly states: "Some organisms use simple food material obtained from inorganic sources in the form of carbon dioxide and water. These organisms, the autotrophs, include green plants and some bacteria." For a fill-in-the-blank 1-mark question, the single word autotrophs is the complete answer required.

Answer: B — Green plants

Green plants are autotrophs; they prepare their own food using CO₂, water, and sunlight (photosynthesis). Fungi and animals are heterotrophs; tapeworms are parasites.

The textbook (Chapter 5) states: "autotrophs include green plants and some bacteria." Fungi and animals are explicitly listed as heterotrophs. Tapeworms are parasitic heterotrophs. Examiners expect you to recall this direct definition.

Bio-catalysts used by organisms to break down complex substances into simpler ones are called enzymes.

The passage directly states: "To achieve this, organisms use bio-catalysts called enzymes." This is a straightforward one-word/one-line answer. Examiners award the mark for the term "enzymes." No elaboration is needed for 1 mark.

Source: Chapter 5, Section 5.2 Nutrition

The green organelles in leaf cells that contain chlorophyll are called chloroplasts.

Source: Life Processes, Section 5.2.1

The passage directly states: "These green dots are cell organelles called chloroplasts which contain chlorophyll." Examiners expect the exact term chloroplasts. No further explanation is needed for a 1-mark question — just the name.

The following three events occur during the process of photosynthesis:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

Source: Chapter 5, Section 5.2.1 Autotrophic Nutrition

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• The question directly asks you to list three events, so a numbered list is ideal — no extra elaboration needed.
• These three points are explicitly stated in the textbook as "(i), (ii), (iii)" under "What actually happens during photosynthesis," so reproduce them as given.
• Each point carries 1 mark, so one clear line per point is sufficient.
• Avoid mixing in details about stomata, starch storage, or chloroplasts — those are not the "events" asked for here.

Plants store carbohydrates that are not used immediately in the form of starch, which serves as an internal energy reserve.

Source: Life Processes, Section 5.2.1 Autotrophic Nutrition

The answer is directly stated in the passage. The key term examiners look for is starch. You may also add "internal energy reserve" to complete the point. No extra elaboration is needed for 1 mark.

Energy from food is stored in our bodies in the form of glycogen.

Source: Chapter 5, Section 5.2.1 (Autotrophic Nutrition)

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The passage explicitly states: "some of the energy derived from the food we eat is stored in our body in the form of glycogen." Examiners expect the specific term glycogen — not just "carbohydrates" or "starch." One word/one line is sufficient for 1 mark.

The tiny pores on the surface of leaves through which gaseous exchange takes place are called stomata.

This is a direct one-word fill-in-the-blank. The textbook (Chapter 5) states that plants exchange gases through stomata. Examiners expect the exact term "stomata" (singular: stoma). No further explanation is needed for 1 mark.

Answer: B – Guard cells

Guard cells control the opening and closing of the stomatal pore by changing their turgidity.

Guard cells are specialised cells that surround each stoma. When they absorb water and become turgid, the pore opens; when they lose water and become flaccid, the pore closes. Examiners expect the direct answer "Guard cells" for 1 mark — no elaboration is strictly necessary, but one supporting line shows understanding.

When the plant does not need carbon dioxide (i.e., photosynthesis is not occurring), keeping stomata open would cause unnecessary water loss through transpiration. Therefore, the plant closes the stomatal pores to conserve water. This closing happens when the guard cells lose water and shrink, causing the pore to close.

Source: Chapter 5, Section 5.2.1 — Autotrophic Nutrition

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• The examiner expects two linked points: (1) open stomata cause water loss, and (2) the mechanism — guard cells shrink → pore closes.
• Do not just say "to prevent water loss" without mentioning the guard cell mechanism; the second mark is for the mechanism.
• The key phrase from the textbook is: "the plant closes these pores when it does not need carbon dioxide for photosynthesis" and "the pore closes if the guard cells shrink."

Two minerals (other than nitrogen) that plants take up from the soil are phosphorus and magnesium (also iron, potassium, etc. are acceptable).

This question is from Chapter 5 (Life Processes), specifically the section on autotrophic nutrition, where the textbook mentions that plants take up water, minerals (nitrogen, phosphorus, magnesium, iron, etc.) from the soil. Any two correct mineral names earn the mark. The source passages provided here don't detail this directly, but it is standard NCERT Class 10 content from Chapter 6 (Life Processes). Write just two mineral names clearly for full marks.

Nitrogen is essential for plants because it is used to synthesise proteins and other substances required for growth and development of the plant body.

The passage states that organisms need materials from outside to "grow, develop, synthesise protein and other substances." Nitrogen is the key element needed for protein synthesis in plants. For a 1-mark answer, simply state this function — one clear, direct line is sufficient. Examiners look for the keyword protein synthesis / growth.

| Autotrophic Nutrition | Heterotrophic Nutrition |
|---|---|
| Organisms prepare their own food using simple inorganic substances (CO₂ and water). | Organisms depend on complex food prepared by other organisms. |
| External energy source (sunlight) and chlorophyll are required. | Enzymes are used to break down complex food into simpler substances. |
| Examples: green plants, some bacteria. | Examples: animals, fungi. |

Autotrophic nutrition involves intake of simple inorganic materials and synthesis of complex organic food. Heterotrophic nutrition involves intake of ready-made complex material, which is then broken down for use.

Source: Life Processes, Chapter 5, Section 5.2

• Examiners expect a comparison format — either a table or parallel points. A table is ideal here.
• Three clear points of difference earn full 3 marks (1 mark each).
• Key terms to include: inorganic sources, CO₂, water, sunlight, chlorophyll (autotrophic) vs. complex substances, enzymes, depend on autotrophs (heterotrophic).
• Always give one example for each type — it reinforces the answer without adding unnecessary length.

Cuscuta, ticks, lice, leeches and tape-worms use the parasitic nutritive strategy, deriving nutrition from plants or animals without killing them.

Source: Chapter 5, Section 5.2.2 Heterotrophic Nutrition

The keyword the examiner expects is "parasitic". The textbook explicitly states this word for these exact organisms. Writing "parasitism" is also acceptable. Do not describe it at length — one line is sufficient for 1 mark.

Amoeba is a unicellular organism that obtains food using temporary finger-like extensions called pseudopodia. These extensions surround the food particle and fuse over it, forming a food-vacuole.

Inside the food-vacuole, complex substances are broken down into simpler ones by enzymes. The digested substances then diffuse into the cytoplasm for use by the cell.

The remaining undigested material is moved to the surface of the cell and thrown out.

Source: Chapter 5, Section 5.2.3

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• The answer must mention three stages: ingestion (pseudopodia + food-vacuole), digestion (breakdown inside vacuole + diffusion), and egestion (throwing out undigested material). Each stage is worth ~1 mark.
• The term pseudopodia is good to include even though the passage calls them "temporary finger-like extensions" — both are acceptable.
• Don't confuse Amoeba with Paramoecium (which uses cilia at a fixed spot). Examiners watch for this mix-up.
• Keep the answer concise; three clear points are all that's needed for 3 marks.

In Paramoecium, food is moved to a specific spot by the movement of cilia, which cover the entire surface of the cell.

Source: Chapter 5, Section 5.2.3

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The blank requires a single word: cilia. The passage explicitly states "Food is moved to this spot by the movement of cilia which cover the entire surface of the cell." Examiners expect this exact term — do not write flagella or pseudopodia (those relate to other organisms).

The long tube extending from the mouth to the anus is called the alimentary canal.

Source: Life Processes, Section 5.2.4

This is a direct one-line fill-in-the-blank answer. Examiners expect the exact term "alimentary canal." No additional detail is needed for 1 mark.

Saliva is secreted by the salivary glands in the mouth. It performs two roles:

1. Moistening food — It wets the food to make its passage through the alimentary canal smooth.
2. Chemical digestion — It contains the enzyme salivary amylase, which breaks down starch (a complex molecule) into simple sugars.

Source: Life Processes, Section 5.2.4

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Examiners expect both functions — physical (wetting/lubricating food) and chemical (enzyme action on starch). Simply naming salivary amylase alone fetches only 1 mark. Always mention what the enzyme acts on (starch) and what it produces (simple sugar) for full marks. Keep it concise — two clear points are enough for 2 marks.

The enzyme in saliva that breaks down starch is salivary amylase.

Source: Life Processes, Section 5.2.4

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The textbook explicitly states: "The saliva contains an enzyme called salivary amylase that breaks down starch…into simple sugar." Just naming the enzyme scores the full mark. Avoid writing a lengthy explanation — one line is all that is needed for a 1-mark answer.

The rhythmic muscular contractions that push food forward along the gut are called peristaltic movements (peristalsis).

The textbook (Ch. 5, section 5.2.4) states: "The lining of canal has muscles that contract rhythmically in order to push the food forward. These peristaltic movements occur all along the gut." For a fill-in-the-blank, either "peristalsis" or "peristaltic movements" is acceptable. Don't confuse this with churning movements in the stomach.

The gastric glands in the stomach wall release three substances:

1. Hydrochloric acid (HCl) — creates an acidic medium that facilitates the action of pepsin and kills harmful bacteria.
2. Pepsin — a protein-digesting enzyme that breaks down proteins.
3. Mucus — protects the inner lining of the stomach from the action of the acid.

Source: Life Processes, Section 5.2.4

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The question directly tests recall from the passage: "These release hydrochloric acid, a protein digesting enzyme called pepsin, and mucus." Name all three substances and briefly state the role of each — examiners award marks for both identification and function. Do not confuse gastric glands with other glands (salivary, pancreas, etc.).

Hydrochloric acid (HCl) in the stomach performs two main roles:

1. It creates an acidic medium which is necessary for the activation and proper functioning of the protein-digesting enzyme pepsin.
2. It kills harmful bacteria and pathogens that may enter the stomach with food, preventing infection.

Source: Life Processes, Chapter 5, Section 5.2.4

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The textbook directly states that HCl "creates an acidic medium which facilitates the action of the enzyme pepsin." The passage also hints at another function ("What other function do you think is served by the acid?") — which is killing germs. Examiners expect both points for full 2 marks. Mention pepsin by name; that shows precise recall and earns marks.

Answer: B — Pepsin

The gastric glands in the stomach wall release a protein-digesting enzyme called pepsin. Hydrochloric acid creates an acidic medium which facilitates the action of pepsin.

Source: Life Processes, Section 5.2.4

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• Pepsin is the only enzyme in gastric juice that digests proteins.
• Amylase digests starch (found in saliva/pancreatic juice); Lipase digests fats (pancreatic juice); Trypsin digests proteins but is secreted by the pancreas, not the stomach.
• The key phrase from the textbook: "a protein digesting enzyme called pepsin" — memorise this directly.

Grass contains cellulose, which is difficult to digest. Herbivores need a longer small intestine to allow sufficient time for the complete digestion and absorption of this tough plant material. Carnivores eat meat, which is easier to digest and requires less time, so a shorter intestine is adequate.

Source: Chapter 5, Section 5.2.2 – Heterotrophic Nutrition

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• The key concept is cellulose digestion — grass/plant cell walls are made of cellulose, which is hard to break down and needs more time/surface area.
• The passage from Chapter 5 mentions that a cow and a lion differ in their "nutritive apparatus" because food sources differ (stationary grass vs. mobile prey).
• Examiners expect two points: (1) grass is harder to digest, (2) longer intestine = more time/surface for digestion and absorption.
• Do not write about enzymes in detail — that's beyond what the passage states and wastes words.

Bile salts are secreted by the liver and act on fats present in the small intestine. Fats exist as large globules, making enzyme action difficult. Bile salts break these large fat globules into smaller globules (emulsification), thereby increasing the surface area and making enzyme (lipase) action more efficient.

Source: Life Processes, Section 5.2.4

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The key points examiners look for are:

1. Emulsification — bile salts break large fat globules into smaller ones (the specific term scores marks).
2. Why it matters — increased surface area allows lipase to act more efficiently.

The textbook directly compares this to the emulsifying action of soaps, so using the word "emulsification" is important. Don't confuse bile salts with digestive enzymes — bile contains no enzymes but aids enzyme action.

The finger-like projections on the inner lining of the small intestine are called villi. They increase the surface area for absorption of digested food into the bloodstream.

Source: Life Processes, Section 5.2.4

The examiner expects the term villi (singular: villus) — this is the key word that fetches the mark. Mentioning their function (increasing surface area for absorption) completes the one-line answer. Do not confuse villi with microvilli; at Class 10 level, "villi" is the required term.

The small intestine is specially designed for absorption in the following ways:

1. Length: It is the longest part of the alimentary canal, providing a long surface for absorption.
2. Villi: The inner lining has numerous finger-like projections called villi, which greatly increase the surface area for absorption.
3. Blood supply: The villi are richly supplied with blood vessels, which absorb the digested food (glucose, amino acids, fatty acids, glycerol) and transport it to all cells of the body.

Thus, large surface area and rich blood supply make the small intestine highly efficient for absorption.

Source: Chapter 5, Section 5.2.4 – Nutrition in Human Beings

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Examiners expect three clear points here: (1) villi — name and describe them, (2) increased surface area, and (3) rich blood vessel supply for transport. The word villi is a must. Avoid writing about digestion here — the question is specifically about absorption design. One mark each for the three features.

Option C — Small intestine.

The complete digestion of carbohydrates, proteins and fats takes place in the small intestine.

The small intestine receives secretions from the liver (bile) and pancreas (pancreatic enzymes) that complete the digestion of all three food types. Partial digestion begins earlier (mouth for carbohydrates, stomach for proteins), but completion happens only in the small intestine — this distinction is key for MCQs.

The first step common to all pathways of glucose breakdown is glycolysis — the breakdown of glucose (6-carbon) into pyruvate (3-carbon), producing a small amount of ATP. This process occurs in the cytoplasm of the cell and takes place whether or not oxygen is available.

Source: Life Processes, Chapter 5, Respiration section

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• The examiner expects two key facts: what the step is (glycolysis / breakdown of glucose to pyruvate) and where it occurs (cytoplasm). One mark for each.
• The phrase "common to all pathways" is the hint that glycolysis precedes both aerobic and anaerobic respiration — mention this briefly to show understanding.
• Avoid writing full equations unless asked; a crisp description earns full marks.

Pyruvate is a 3 (three)-carbon molecule.

This is a direct factual recall question. Pyruvate (CH₃COCOO⁻) is produced during glycolysis when a 6-carbon glucose molecule is split into two 3-carbon pyruvate molecules. Just write "3" or "three" — one word/number is sufficient for 1 mark.

When pyruvate is broken down in yeast during fermentation (anaerobic respiration), the products formed are ethanol and carbon dioxide.

Source: Chapter 5, Section 5.3 Respiration

The passage explicitly states: "the pyruvate may be converted into ethanol and carbon dioxide. This process takes place in yeast during fermentation." Both products must be named for full marks. Do not confuse this with aerobic respiration (CO₂ + water) or lactic acid fermentation (in muscles).

Differences between Aerobic and Anaerobic Respiration:

| Basis | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen | Requires oxygen | Occurs without oxygen |
| Site | Cytoplasm + mitochondria | Cytoplasm only |
| End products | CO₂ + water + energy | Ethanol + CO₂ + energy (in yeast); lactic acid + energy (in muscles) |
| Energy released | Large amount (more ATP) | Small amount (less ATP) |
| Completeness | Glucose completely broken down | Glucose partially broken down |

Organisms using anaerobic respiration: Yeast is a common example. Certain bacteria also respire anaerobically. Even human muscle cells temporarily switch to anaerobic respiration during vigorous exercise, producing lactic acid, which causes muscle cramps.

Source: Chapter 5, Life Processes

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• Examiners expect a tabular format for "differences" questions — it earns full marks neatly and clearly.
• Mention both end-product examples: ethanol + CO₂ (yeast) and lactic acid (muscle cells) — both are in the syllabus.
• The key scoring point is that aerobic respiration releases more energy than anaerobic. Don't skip this.
• "Name an organism" needs at least one specific example — yeast is the safest answer; mentioning bacteria is a bonus.
• The breakdown of pyruvate occurs in the mitochondria (aerobic) vs cytoplasm (anaerobic) — a commonly tested detail.

During sudden activity, muscles work vigorously and need more energy. When oxygen supply is insufficient, glucose is broken down anaerobically, producing lactic acid. The accumulation of lactic acid in the muscle cells causes cramps — a painful sensation due to lack of proper oxygen supply during the sudden exertion.

Source: Chapter 6, Life Processes (related biochemistry of muscle activity)

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• The examiner expects the key terms: anaerobic respiration, lactic acid accumulation, and insufficient oxygen.
• Many students lose marks by only saying "lactic acid builds up" without explaining why (oxygen shortage during sudden activity).
• This concept links to Chapter 6 muscle action and energy release — keep the answer focused on the biochemical cause, not just the symptom.

ATP (Adenosine Triphosphate) is the energy currency for most cellular processes. During respiration, glucose is broken down to provide energy in the form of ATP, which is then used to drive other reactions in the cell.

Source: Life Processes, Chapter 5 (What you have learnt)

The key phrase from the NCERT summary is: "energy in the form of ATP. ATP is used to provide energy for other reactions in the cell." Examiners expect the full form and the reason (produced during respiration, used to drive cellular reactions). One line is sufficient for 1 mark — do not over-elaborate.

Aquatic organisms like fish use oxygen dissolved in water for breathing. The amount of dissolved oxygen in water is much less compared to the oxygen present in air. Therefore, aquatic organisms have to breathe much faster to absorb sufficient oxygen to meet their body's requirements.

Source: Life Processes, Chapter 5

The examiner expects two clear points: (1) aquatic organisms use dissolved oxygen from water, and (2) dissolved oxygen in water is far less than in air — so faster breathing compensates for the low oxygen availability. Both points are needed for full 2 marks. Avoid writing about terrestrial breathing mechanisms; just contrast oxygen availability in water vs. air.

The balloon-like structures in the lungs where exchange of gases takes place are called alveoli (singular: alveolus).

The examiner expects the term "alveoli." These are tiny air sacs with thin walls and a rich network of blood capillaries, enabling efficient exchange of O₂ and CO₂. Just one word/term is sufficient for 1 mark, but naming them as "balloon-like air sacs called alveoli" is safer.

The lungs are specially designed to provide a large surface area for gas exchange through the following features:

1. Branching airways: The trachea divides into two bronchi, which further divide into smaller bronchioles, ending in tiny balloon-like structures called alveoli.

1. Numerous alveoli: Each lung contains millions of alveoli, which together provide a very large surface area (approximately the size of a tennis court) for gas exchange.

1. Thin walls: Alveolar walls are extremely thin (one cell thick), allowing gases to diffuse quickly across them.

1. Rich blood supply: Alveoli are surrounded by a dense network of blood capillaries, ensuring efficient and continuous exchange of oxygen and carbon dioxide between air and blood.

1. Moist surface: The inner lining of alveoli is moist, allowing gases to dissolve and diffuse easily.

These structural adaptations together maximise the rate and efficiency of gas exchange in the lungs.

Source: Chapter 5 – Life Processes, Section 5.3 Respiration

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• The examiner expects you to name and explain alveoli as the key structure — this is the central point of the answer.
• Mention the hierarchical branching (trachea → bronchi → bronchioles → alveoli) to show how the design leads to increased surface area.
• Four key features earn marks: large surface area (alveoli), thin walls, rich capillary network, and moist lining.
• Avoid vague statements like "lungs are big" — be specific about how surface area is maximised.
• This is a standard 5-mark question; 5 distinct labelled points work well here.

Haemoglobin is the respiratory pigment in human beings. It is present in red blood corpuscles (RBCs) and has a high affinity for oxygen, helping transport oxygen to all body cells.

Source: Chapter 5, Section 5.4.1

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• The examiner expects the name haemoglobin as the direct answer — that single word earns the mark.
• Adding that it is found in RBCs and transports oxygen shows understanding and is good practice for 1-mark answers.
• Do not confuse it with plasma, which transports CO₂ and food in dissolved form — that is a common mistake.

Transport of Oxygen:
Oxygen is carried by the red blood corpuscles (RBCs), which contain haemoglobin. Haemoglobin binds with oxygen in the lungs and releases it to the body cells.

Transport of Carbon dioxide:
Carbon dioxide is transported in dissolved form in the plasma. It travels from body tissues to the lungs, where it is removed from the blood and expelled during exhalation.

Both substances are transported through the circulatory system consisting of the heart, blood, and blood vessels.

Source: Chapter 5, Section 5.4.1 – Transportation in Human Beings

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• Examiners expect students to clearly distinguish between how O₂ and CO₂ are transported — this is the core of the answer.
• Key point: O₂ → RBCs (haemoglobin); CO₂ → plasma (dissolved form). Both facts must appear to get full marks.
• Mentioning the circulatory system as the medium of transport adds completeness for a 3-mark answer.
• Do not confuse: CO₂ is not carried by RBCs in this context — the textbook specifically states plasma carries CO₂ in dissolved form.

The rings of cartilage in the throat (trachea) keep the airway from collapsing, ensuring the passage remains open so that air can flow freely into the lungs at all times.

Though not explicitly detailed in the given passages, this is standard NCERT Class 10 Biology content (Life Processes, Chapter 6). Examiners expect students to state two key points in one line: (1) the rings prevent collapse of the trachea, and (2) they ensure a continuous, unobstructed air passage. Avoid writing a lengthy answer — one clear sentence is sufficient for 1 mark.

Answer: B — Arteries

Arteries are the vessels which carry blood away from the heart to various organs of the body.

Source: Life Processes, Section 5.4.1 (The tubes – blood vessels)

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The textbook directly states: "Arteries are the vessels which carry blood away from the heart to various organs of the body." Veins do the opposite (bring blood back to the heart). For MCQs, quote or closely paraphrase the textbook definition — examiners award the mark for the correct option with a supporting reason.

Platelet cells help in clotting the blood at points of injury. They circulate in the blood and plug leaks in blood vessels, preventing excessive blood loss and maintaining pressure in the circulatory system.

Source: Life Processes, Section 5.4.1 – Maintenance by platelets

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The examiner expects the key function: blood clotting / plugging leaks at injury sites. The textbook phrase "plug these leaks by helping to clot the blood at these points of injury" is the core idea. Mentioning prevention of blood loss and maintenance of pressure adds completeness for a 1-mark answer but the single essential point is clotting/plugging leaks.

Mammals and birds are warm-blooded animals that constantly use energy to maintain their body temperature. This means they have high energy needs and require a highly efficient supply of oxygen to the body. If oxygenated and deoxygenated blood were to mix, the efficiency of oxygen supply would decrease. Separating the two types of blood ensures oxygen-rich blood is pumped to the body without dilution, meeting their high energy demands.

Source: Life Processes, Section 5.4.1

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The examiner expects two linked points: (1) mammals and birds are warm-blooded with high energy needs (to maintain body temperature), and (2) separation prevents mixing, allowing highly efficient oxygen supply. Avoid just saying "mixing is bad" — you must connect it to the reason why these animals specifically need it (warm-blooded/high energy). The textbook phrase "highly efficient supply of oxygen" is worth using directly.

A fish heart has two chambers — one atrium and one ventricle. Blood passes through the fish heart only once in one complete cycle (single circulation). The blood is pumped from the heart to the gills for oxygenation, then directly to the rest of the body.

Source: Chapter 5, Section 5.4.1 — Transportation in Human Beings

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The examiner expects two clear facts: (1) two chambers, and (2) single circulation (blood passes once). Naming the chambers (atrium and ventricle) adds accuracy and may fetch full marks. Contrast with double circulation in other vertebrates is not required here but briefly mentioning "single circulation" by name shows command of terminology.

Double Circulation in Human Beings:

In human beings, blood passes through the heart twice in one complete cycle — this is called double circulation.

1. Pulmonary circulation: De-oxygenated blood from the body enters the right atrium → right ventricle → pumped to the lungs for oxygenation.
2. Systemic circulation: Oxygenated blood from the lungs returns to the left atrium → left ventricle → pumped to the rest of the body.

The right side of the heart handles de-oxygenated blood; the left side handles oxygenated blood. The separation of the two sides prevents mixing of oxygenated and de-oxygenated blood.

Why it is necessary:

Double circulation ensures a highly efficient supply of oxygen to body tissues. Mammals and birds are warm-blooded — they constantly use energy to maintain body temperature. Keeping oxygenated and de-oxygenated blood completely separate allows oxygen-rich blood to reach tissues at high pressure, meeting their high energy demands.

Source: Chapter 5, Section 5.4.1 — Transportation in Human Beings

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• Examiners expect two named circuits (pulmonary + systemic) with direction of blood flow.
• Mention the four chambers and their roles briefly.
• The "why necessary" part must link warm-blooded nature → high energy needs → efficient O₂ supply. This is directly from the textbook and is a common scoring point.
• Contrast with fish (single circulation) or amphibians (3-chambered, mixing allowed) can earn extra credit if word count allows.

Lymph (also called tissue fluid) is the colourless fluid involved in transportation. It is similar to blood plasma but contains less protein.

Source: Life Processes, Section 5.4.1 – Lymph

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The examiner expects the name lymph (accept "tissue fluid") along with its two key features: colourless and less protein than plasma. These exact words appear in the textbook, so use them. Do not confuse lymph with plasma — plasma is the fluid part of blood and is not colourless.

Answer: B — Xylem

Xylem transports water and minerals absorbed from the soil upward to all parts of the plant through vessels and tracheids.

Source: Life Processes, Section 5.4.2

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• Xylem = water + minerals (soil → leaves); Phloem = food/sugars (leaves → other parts). Don't mix these up — it's a very common error.
• Cortex and Epidermis are structural tissues, not transport tissues.
• Exercise Q2 in the chapter directly states: "The xylem in plants are responsible for transport of water."

The loss of water in the form of vapour from the aerial parts of the plant is called transpiration.

This is a direct fill-in-the-blank question worth 1 mark. The examiner expects only the term "transpiration." It is related to the topic of stomata and water loss in plants covered in Chapter 5 (Life Processes). Remember: transpiration occurs mainly through stomata present on leaves and other aerial parts.

Transport of Water and Minerals in Plants:

Water and minerals are transported in plants through xylem — a component of vascular tissue.

Process:

1. Water and dissolved minerals are absorbed from the soil by root hair cells through osmosis and active transport.
2. They move from root cells into the xylem vessels.
3. The transpiration pull (loss of water vapour through stomata in leaves) creates a suction force that pulls water upward continuously through the xylem.
4. This creates a continuous column of water from roots to leaves — called the transpiration stream.

Key points:

• Xylem is made of dead cells forming hollow tubes — suited for water conduction.
• Minerals dissolved in water are carried along with it through xylem.
• Transpiration pull is the main driving force for upward movement of water.

Source: Life Processes, Chapter 5, Vascular Tissue section

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• Examiners expect: xylem → root absorption → transpiration pull → upward movement — these are the four scoring steps.
• Mention that xylem carries both water and minerals (not just water).
• "Transpiration pull" is the key term — must be used.
• Do NOT confuse with phloem (which carries food/sucrose). If the question were about both, phloem would need separate treatment — here only water and minerals are asked, so xylem is the focus.
• Avoid long introductions; get to the mechanism quickly in board exams.

| Basis | Xylem | Phloem |
|-------|-------|--------|
| Substances transported | Water and minerals | Sugars (sucrose), amino acids, and other products of photosynthesis |
| Direction of transport | Unidirectional — upward (roots to leaves) | Bidirectional — upward and downward |
| Driving force | Physical forces — root pressure and transpiration pull (no energy required) | Energy from ATP is used; an active process |
| Conducting elements | Vessels and tracheids | Sieve tubes and companion cells |

Source: Life Processes, Section 5.4.2

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Examiners look for four clear points of difference for 3 marks — a table is the neatest format. The key contrasts are: what is transported, direction, energy requirement, and tissue/cells involved. Students often forget that phloem transport is bidirectional and requires ATP (active process), while xylem relies on passive physical forces. Mentioning companion cells alongside sieve tubes adds accuracy.

The transport of soluble products of photosynthesis from leaves to other parts of the plant is called translocation.

The term "translocation" refers specifically to the movement of food (sucrose/sugars) through the phloem. The source passage mentions that phloem transports food materials in plants. Examiners expect the single correct term; no further explanation is needed for a 1-mark blank-fill question.

The excretory system of human beings consists of the following parts:

1. A pair of kidneys – filter waste (urea) from blood and produce urine.
2. A pair of ureters – carry urine from kidneys to the urinary bladder.
3. Urinary bladder – stores urine until it is released.
4. Urethra – passes urine out of the body.

Source: Life Processes, Section 5.5.1

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The question asks you to list parts — so a labelled list with a brief function for each part is ideal for 2 marks. Examiners expect all four components to be named; missing even one can cost half a mark. Mentioning the basic function of each part (filtration, transport, storage, expulsion) adds precision and shows understanding, which is rewarded in board marking.

The basic filtration unit of the kidney is called the nephron. Each kidney contains a large number of nephrons packed close together.

Source: Life Processes, Section 5.5.1

The examiner expects the term nephron — this single word (with a brief supporting statement) is sufficient for 1 mark. Avoid lengthy descriptions of nephron structure here; that is asked in a separate 5-mark question. Just naming it correctly, perhaps with the note that kidneys contain many nephrons, is enough.

Structure of a Nephron:

A nephron is the basic filtration unit of the kidney. It consists of:

• Bowman's capsule – a cup-shaped structure enclosing a cluster of capillaries called the glomerulus.
• Renal tubule – a long coiled tube leading from Bowman's capsule, divided into the proximal convoluted tubule, loop of Henle, and distal convoluted tubule, which opens into the collecting duct.

Functioning:

1. Filtration: Blood entering the glomerulus is filtered under pressure; water, glucose, amino acids, urea, and salts pass into Bowman's capsule as glomerular filtrate.
2. Reabsorption: As filtrate moves through the tubule, useful substances (glucose, amino acids, water, salts) are reabsorbed back into the blood.
3. Excretion: The remaining filtrate (urine), containing urea and excess salts, passes into the collecting duct and then to the ureter.

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• Examiners expect both structure and functioning addressed separately and clearly.
• Label the key parts: glomerulus, Bowman's capsule, renal tubule, collecting duct.
• The three functional steps — filtration → reabsorption → excretion — must all appear for full marks.
• A labelled diagram of the nephron, if drawn neatly, can earn 1 mark and compensate for minor omissions in text.
• Note: No source passages on nephrons were provided; this answer is based on standard CBSE Class 10 Biology Chapter 6 (Life Processes) content.

The amount of urine produced is regulated by the process of selective reabsorption in the kidney tubules. The amount of water reabsorbed depends on:

• How much excess water is present in the body.
• How much dissolved waste needs to be excreted.

If excess water is available, less is reabsorbed and more urine is produced, and vice versa.

Source: Chapter 5, Section 5.5.1

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Examiners expect two key points: (1) the mechanism — selective reabsorption of water in kidney tubules, and (2) the two factors that control it — excess water in the body and amount of dissolved waste. Avoid writing about nephron structure in detail; this question is specifically about regulation, not production. Mentioning both factors earns full marks.

Answer: A — Storing wastes in cellular vacuoles

Plants store waste products in cellular vacuoles, in fallen leaves, as resins and gums in old xylem, and also excrete some wastes into the surrounding soil.

Source: Life Processes, Section 5.5.2

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• Options B, C, and D (kidneys, alveoli, nephrons) are all structures found in animals/humans, not plants.
• The textbook explicitly states: "Many plant waste products are stored in cellular vacuoles" — making A the only correct option.
• In MCQs, eliminate animal-specific organs first; then match the remaining option to the plant excretion strategies listed in the chapter.

Waste products in old xylem of plants are stored as resins and gums.

Source: Life Processes, Section 5.5.2 – Excretion in Plants

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The question is directly from Section 5.5.2. The textbook states: "Other waste products are stored as resins and gums, especially in old xylem." Just naming the two forms (resins and gums) is sufficient for 1 mark. Do not confuse this with waste stored in cellular vacuoles or fallen leaves — those are different storage/excretion strategies in plants.

Haemoglobin present in red blood cells carries oxygen to all body cells. Its deficiency would mean:

• Less oxygen is transported to body cells, reducing energy production.
• The person would feel tired and weak.
• Carbon dioxide removal from tissues may also be affected.
• This condition leads to anaemia, causing breathlessness and fatigue.

Source: Life Processes, Section 5.4.1

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• The key fact is that haemoglobin carries oxygen in red blood cells — state this first.
• Consequences to mention: reduced oxygen supply → less energy → weakness/fatigue → anaemia. Two or three clear consequences are enough for 2 marks.
• Examiners expect the term anaemia to be used.
• Do not write about the heart or blood pressure — stay focused on haemoglobin's role in oxygen transport.

Necessary conditions for autotrophic nutrition (photosynthesis):

1. Carbon dioxide and water – raw materials taken from the environment.
2. Chlorophyll – the green pigment that absorbs light energy.
3. Sunlight – the external energy source for the reaction.

These are used to synthesise carbohydrates (glucose/starch) from CO₂ and water.

Byproducts:

• Oxygen is released during the splitting of water molecules.
• Water is also produced as a byproduct of the reaction.

The carbohydrates not immediately used are stored as starch.

Source: Chapter 5, Section 5.2.1 Autotrophic Nutrition

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Examiners look for all three necessary conditions (CO₂ + water, chlorophyll, sunlight) and oxygen as the main byproduct — that alone can fetch 2 marks. The third mark often goes to mentioning carbohydrates/starch as the product and oxygen from water-splitting as the key byproduct. Question 3 in the exercises directly hints that "all of the above" (CO₂, water, chlorophyll, sunlight) are required — use that as a memory anchor.

A terrestrial organism breathes air directly, which contains about 21% oxygen. Since oxygen is freely and abundantly available in the atmosphere, it can be taken in easily.

An aquatic organism, however, must use the oxygen dissolved in water, which is present in much smaller amounts. This makes obtaining sufficient oxygen harder and more energy-consuming for aquatic organisms.

Source: Life Processes, Chapter 5, Section 5.1

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The examiner expects two clear points: (1) oxygen is more abundant/easily available in air than dissolved in water, and (2) this gives the terrestrial organism an advantage in meeting its oxygen needs for respiration. Avoid over-explaining; two focused comparative sentences are enough for 2 marks.

Option B: Mitochondria

The breakdown of pyruvate using oxygen (aerobic respiration) takes place in the mitochondria.

Source: Life Processes, Chapter 5 (Exercise Q.4)

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The textbook exercise (Q.4) directly states that breakdown of pyruvate to give carbon dioxide, water and energy takes place in the mitochondria. This is a standard fact: mitochondria are the site of aerobic respiration. Cytoplasm is where glycolysis (glucose → pyruvate) occurs; the subsequent oxygen-dependent breakdown of pyruvate happens inside the mitochondria. Examiners expect the single correct option — B.

Ventricles pump blood to distant organs — the right ventricle pumps blood to the lungs and the left ventricle pumps blood to the entire body. This requires much greater force and pressure. Atria only receive blood and push it into the ventricles over a short distance, needing less muscular effort. Hence, ventricles have thicker walls.

The examiner expects two linked points: (1) the function of ventricles (pumping blood over longer distances/to the whole body) requires more force, and (2) atria perform easier work (receiving blood). Always connect structure to function — this is the core biology principle being tested here. Note: this topic is from Chapter 7 (Life Processes – Transportation), not the provided passages, so the answer is based on standard NCERT content.

Arteries carry blood away from the heart under high pressure, so the blood flows continuously forward — no valves are needed.

Veins carry blood back to the heart under low pressure. Without valves, blood could flow backwards. The valves in veins ensure blood flows only in one direction — towards the heart.

Source: Chapter 5, Section 5.4.1 – The tubes – blood vessels

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The textbook directly states: arteries have thick, elastic walls (to withstand high pressure) while veins have valves because blood is no longer under pressure and needs to be prevented from flowing backwards. Examiners expect both parts — why arteries don't need valves AND why veins do — for full 2 marks. Use keywords: high pressure (arteries) and one direction / prevent backflow (veins).

Digestive enzymes break down complex food substances (like starch, proteins, and fats) into simpler, smaller molecules (like glucose, amino acids, fatty acids) that can be absorbed by the body.

The examiner expects a direct, functional statement. Key idea: enzymes are biological catalysts that break complex molecules → simpler molecules for absorption. Mentioning one or two examples (amylase, pepsin, lipase) strengthens the answer but is not compulsory for 1 mark.

Digestion of fats takes place in the small intestine.

Fats are present as large globules in the small intestine. The liver produces bile juice, which is stored in the gall bladder and released into the small intestine. Bile breaks down large fat globules into smaller droplets — a process called emulsification. This increases the surface area for enzyme action. Then, lipase enzyme (secreted by the pancreas) acts on the emulsified fats and breaks them down into fatty acids and glycerol, which are then absorbed by the intestinal walls.

Source: Life Processes, Chapter 5 (Nutrition in Human Beings)

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• Examiners expect three key steps: bile emulsifies fats → lipase digests them → products absorbed — each step earns a mark.
• Name the site clearly: small intestine (specifically, bile comes from liver/gall bladder; lipase from pancreas).
• The term emulsification is important — use it explicitly.
• Do not confuse emulsification (physical breakdown) with enzymatic digestion (chemical breakdown).