NCERT Solutions for Class 9th Science Chapter 12 Gymnosperms — Pause and Ponder

Book page 238 Updated on2026-09-08

Q3.

Which plant features reduce their dependence on water but still require moist conditions?

Answer

The features that reduce dependence on water are the ones that solve transport and support; the features that keep the plant tied to moisture are the ones connected with reproduction. Pteridophytes are the group where these two pull in opposite directions.

Feature	What it frees the plant from	What it does not solve
True roots	Reaching water deeper than the plant body; anchorage	—
Xylem and phloem	Carrying water and food to a tall body, and stiffening the stem	—
A cuticle on the leaf	Losing water to dry air	—
Motile male gametes	—	The sperm must swim to the egg, so a film of water is essential for fertilisation
No seed	—	The spore has no stored food or protective coat, so it can germinate only where it is already damp

Why the split exists: vegetative life and reproduction are two separate problems. A fern's roots and vascular tissue let it grow well away from open water and stand a metre high. But at the moment of fertilisation the male cell has to travel to the female cell under its own power, and it can only swim. Solve transport and you can live on land; you cannot breed on dry land until you solve fertilisation as well. That is exactly what gymnosperms do next — and it is why the chapter titles them "Reproduction without water".

Bryophytes fit the same pattern one step lower. They have rhizoids and a slightly differentiated body, so they left the water; but with no vascular tissue and swimming sperm, they need moisture both to live and to breed. Hence the name — 'amphibians' of the plant kingdom.

Q4.

Why do taller plants need specialised transport tissues?

Answer

Because diffusion is far too slow over long distances, and because a tall body needs something rigid to hold it up. Transport tissue answers both needs at once.

The distance problem. Diffusion works well over fractions of a millimetre and hopelessly badly over metres — the time taken rises with the square of the distance. In a moss a few centimetres tall, water absorbed at the surface reaches every cell. In a fern, a pine or a gulmohar tree, the leaves may be metres above the soil and the roots metres below the nearest leaf. Neither end can supply the other by diffusion.

Roots absorb water — but cannot photosynthesise.
Leaves make food — but cannot reach the soil.
Xylem: water + minerals, roots → leaves.
Phloem: food, leaves → every other part, including roots.
Without both, one end of a tall plant starves and the other dries.

The support problem. Xylem is more than a pipe. Its cells have thick walls stiffened with lignin and they die at maturity, leaving hollow, rigid tubes. Bundled together these behave like scaffolding — the same tissue that carries the water also holds the plant upright. A small plant can be held up by the turgor pressure of its cells alone; a tall one cannot. This is why no non-vascular plant is tall, and why wood (which is mostly old xylem) is what lets trees exist.

Why height is worth the cost: light. A taller plant intercepts sunlight before its neighbours do. Every structure in this section — roots, xylem, lignin, cambium — is part of the price plants pay to get their leaves above the competition.

Q5.

How do seeds and fruits affect, where and how plants can survive?

Answer

Seeds free a plant from needing water to reproduce; fruits free its offspring from having to grow where the parent stands. Together these two structures explain why angiosperms are the most diverse plant group on the Earth.

What the seed does

It protects the developing embryo inside a tough coat, so the new plant can survive drying, cold and time — it can wait, dormant, until conditions are right.
It contains stored food, so the seedling is fed until its own leaves open. A spore has neither coat nor food store, which is why a fern spore can only germinate somewhere already moist and sheltered.
In gymnosperms and angiosperms, water is not required for fertilisation — pollen carries the male gamete to the ovule, so the sperm never has to swim. This is the single change that lets plants breed in dry regions.

What the fruit does

It encloses and protects the seeds while they mature.
It helps spread seeds to new locations — by insects or birds, animals, wind, or water. A seed that germinates under its parent competes with the parent for light, water and minerals; a dispersed seed does not.

How this shows in where plants live:

Gymnosperms — pines and cycads — are well adapted to cold and dry regions. Their needle-like or scale-like leaves reduce water loss, and their seeds sit exposed on cones. Fertilisation without water is what allows them there at all.
Angiosperms add flowers, which attract pollinators and so raise the efficiency of reproduction, and fruits, which move the seeds. These features allow angiosperms to occupy a wide range of environments — from deserts to rainforests to fresh water — and make them the most diverse plant group on the Earth.

Did you know? The angeion in "angiosperm" means vessel and spermos means seed — literally "seed in a vessel", the fruit. Gymnos means naked: a gymnosperm's seed sits bare on the cone.

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