Sexual Reproduction in Plants (13.5.2) — "Our Home: Earth, a Unique Life Sustaining Planet"

1. 13 marks

   Explain why sexual reproduction doesn't cause the amount of genetic instructions to double every generation, using the chapter's own explanation of gametes.

   Hint. The chapter directly poses this puzzle, then resolves it with one key fact about how much genetic material each gamete carries.

   ✦ Each parent makes specialised reproductive cells called gametes, which carry only half of the parent's genetic material. When male and female gametes join, they form a new cell with a complete set of instructions — half from each parent — so the offspring ends up with one full set of instructions overall, not double, since each parent only ever contributed half to begin with.

2. 23 marks

   Identify the male and female gametes in a flower, and state exactly where in the flower each is found.

   Hint. One is found in a specific part near the top of the flower's reproductive structure; the other is deeper inside.

   ✦ Pollen grains, found inside the anther of a flower, are the male gametes. Ovules, found deep inside the flower, are the female gametes.

3. 33 marks

   Distinguish pollination from fertilisation, in the sequence the chapter describes for plants.

   Hint. One step is about pollen physically arriving somewhere; the other is about the male and female gametes actually combining.

   ✦ Pollination is the process by which pollen is carried to another flower by wind, insects, or animals. Fertilisation is the separate, later step where the male and female gametes actually combine, forming a zygote that becomes the seed — pollination has to happen first, since only then is the male gamete close enough for fertilisation to take place.

4. 43 marks

   What becomes of the ovule and the fleshy part of the flower around it, after fertilisation?

   Hint. Two different parts of the flower develop into two different things you'd recognise from a kitchen.

   ✦ After fertilisation, the ovule develops (via the zygote) into the seed, while the fleshy part of the flower around the ovule develops into the fruit — since these are the two familiar plant products that grow directly out of the flower's own reproductive structures.

5. 53 marks

   Using the banyan seed example, explain how animals help plants disperse their seeds, and why this matters for the plant.

   Hint. The chapter traces one seed's entire journey, from being eaten to sprouting somewhere completely different.

   ✦ When birds or animals eat fruit, the seeds inside often get dropped far from the original plant — a helpful way for plants to spread. The chapter's example: 'a banyan seed, dropped by a bird that ate a fruit and excreted the seed, might sprout in a crack in a wall after the rains.' This matters for the plant because it lets offspring establish in new locations, rather than all competing for the same limited space, water and sunlight right next to the parent plant.

6. 62 marks

   What happens once a seed gets water, according to the chapter — and how does this connect to what students observed in Grade 6?

   Hint. The seed already contains what it needs to begin growing, without needing outside food yet.

   ✦ When seeds get water, they use stored nutrients to grow roots and shoots — this is germination, since Grade 6 students had already studied it directly, observing tiny shoots and the first leaves appear from a seed.

Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 13 (hecu113.pdf), Reprint 2026-27, pages 210-228. Questions are referenced from the NCERT textbook for identification.