Science — CBSE Class 10 board question

(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)

---

• 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.