CBSE Class 7 Science Advanced Biology Reproduction in Plants Short Answer Questions Set 01

Short Answer Questions

Question 1. What are the different types of natural stem propagation?
Answer:
There are three types.
1. Bulb: a food-storing stem with buds, as in onion and garlic.
2. Stem tuber: a swollen underground stem with buds in its eyes, as in potato.
3. Runner: a weak stem that creeps and roots at the ground, as in grass and wild strawberry.
In simple words: Stems can give new plants as bulbs, tubers or runners.

Teacher's Note:
1. Give an example with each type.
2. Potato is a stem, not a root.

Question 2. What is germination and why is it important?
Answer:
Germination is the sprouting of a seedling from a seed after it has been dispersed and gets favourable conditions (water, suitable temperature and oxygen).
It is important because the germinated seed grows into a baby plant, so it starts the next generation of the plant.
In simple words: A seed waking up and growing into a seedling.

Teacher's Note:
1. Radicle comes out first, then plumule.
2. Seeds wait until conditions are right.

Question 3. What is fertilization?
Answer:
Fertilization is the fusion of the male gamete with the female gamete (egg) to form a zygote. In sexual reproduction one parent gives the male gamete and the other gives the female gamete.
In simple words: Male and female gametes join into one cell.

Teacher's Note:
1. The result is called a zygote.
2. In flowers it follows pollination.

Teacher's Note:
1. Draw an onion and a potato in your notebook.
2. The book wrongly says the potato 'roots' swell; it is the stem.

Teacher's Note:
1. Sepals make calyx; petals make corolla.
2. Both are modified leaves.

Question 6. How does pollen reach egg?
Answer:
1. The pollen grains from the anther land on the sticky stigma through pollination.
2. From the stigma the pollen grows down through the style, which connects the stigma to the ovary.
3. Through the style the pollen reaches the ovule and fuses with the egg. This is fertilization.
In simple words: Pollen travels down the style to the egg.

Teacher's Note:
1. In textbooks of higher classes this path is called the pollen tube.
2. Pollination comes before fertilization.