NCERT Solutions for Class 8th Science Chapter 13 .5.1 Asexual reproduction — In-text Questions
Book page 22113 Updated on2026-09-08
Q1.
How do bamboo and sugarcane grow into new plants? I have never seen their seeds.
Answer
They multiply by vegetative propagation — a piece of the parent plant itself grows into a new plant, so no seed is needed.
Sugarcane is grown from short pieces of stem called setts. Each piece carries a node with a bud (an 'eye'). Laid in moist soil, the bud sends up a shoot and the node sends down roots.
Bamboo spreads mainly through underground stems (rhizomes) that creep sideways and send up new culms; a cut piece of culm with a node can also root.
Why it happens: A node of a stem is not just packaging — it carries a bud of living, dividing tissue plus stored food. Given moisture, air and warmth, that tissue can build roots downward and a shoot upward, which is everything a plant needs to become independent. This is asexual reproduction: a single parent, and offspring that are exact copies in terms of the instructions inside the cells.
Did you know? Because every cane in a field comes from the same parent, they are all identical — which is why a whole sugarcane crop can ripen together, and also why a single disease can sweep through the entire field.
Q2.
Can you observe and list some plants around you that grow this way?
Answer
Many of the plants in a kitchen, a garden or a field are grown from parts, not seeds. Look for the part that is planted — that tells you which type of vegetative propagation it is.
Plant
Part that is planted
Where you can see it
Potato
Tuber with 'eyes' (buds)
A sprouting potato in the kitchen
Ginger, turmeric
Rhizome (underground stem)
Kitchen, kitchen garden
Onion, garlic
Bulb
Kitchen, market
Sugarcane
Stem cutting with a node
Sugarcane fields
Money plant, rose, hibiscus, bougainvillea
Stem cutting
School garden, balcony pots
Banana
Sucker growing from the base
Banana plantation, backyard
Bryophyllum
Leaf — buds grow at the notches of the margin
Garden hedges, pots
Sweet potato, dahlia
Root
Fields, flower beds
Grass, mint
Runner — a stem creeping along the ground that roots at nodes
Lawn, kitchen garden
Check it yourself: Walk round your school garden with this table. For every plant, ask 'if I cut a piece and planted it, would it grow?' Then try it with one — a money plant cutting in a glass of water shows roots within about a week.
Q3.
You might wonder if both parents pass on their genetic material for making a new organism, won’t the child end up with double the amount of instructions? And would not this keep doubling every generation?
Answer
No — and the reason is that each parent does not pass on its whole set. Each makes specialised reproductive cells called gametes, and a gamete carries only half the parent's genetic material.
male gamete (half a set) + female gamete (half a set) = new cell with one complete set half from each parent — not double
Halving at each parent, then joining: the amount of genetic material stays the same generation after generation.
Why it happens: If gametes carried a full set, the amount would indeed double every generation — 1, 2, 4, 8 — which is impossible. Halving before joining is what keeps the total constant. And because it is a different half each time, the same step that keeps the quantity steady is also the step that produces variation.