Question

Write the main difference between self-pollination and cross-pollination.

Answer 1

Self-Pollination: Transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant.
Cross-Pollination: Transfer of pollen grains from the anther of one flower to the stigma of a flower on a different plant of the same species.

Self-Pollination	Cross-Pollination
Pollination occurs within the same flower or between flowers of the same plant.	Pollination occurs between flowers of two different plants of the same species.
Does not require external agents like wind, water, or insects for pollination.	Requires external agents like wind, wa- ter, or insects for pollination.
Ensures genetic uniformity as no new genetic material is introduced.	Promotes genetic diversity as genetic material is exchanged between different plants.
Less adaptive to environmental changes due to lack of variation.	More adaptive to environmental changes due to increased genetic variation.
Produces fewer seeds as there is limited pollination.	Produces more seeds as cross- pollination increases chances of fertilization.

Answer 2

Step 1: Identifying the part that attracts insects:
- The petals of a flower are responsible for attracting insects for pollination.
- They are usually brightly colored and sometimes scented to lure insects such as bees and butterflies.

Step 2: Role in pollination:
- When insects are attracted to the flower by the petals, they come in contact with the pollen grains.
- As insects move from flower to flower, they transfer pollen from the anther of one flower to the stigma of another, enabling pollination.

Step 3: What happens after fertilisation:
- Once fertilisation occurs, the reproductive process is complete.
- The flower no longer needs to attract insects, so the petals usually wither and fall off.
- The plant now focuses energy on the development of seeds and fruit.

Step 4: Conclusion:

Petals are the part of the flower that attracts insects for pollination. They are often brightly colored and may have a scent to lure insects.
After fertilisation, the petals usually wither and fall off.

Answer 3

Step 1: Understanding fertilisation:
- Fertilisation is the biological process in which the male gamete (pollen) fuses with the female gamete (ovum or egg) to form a zygote.
- This fusion occurs inside the ovary of a flower, typically within the ovule.

Step 2: Process of fertilisation in flowers:
1. Pollen grains from the anther land on the stigma of a flower.
2. A pollen tube grows from the pollen grain through the style and reaches the ovary.
3. The male gamete travels through the pollen tube and fuses with the female gamete present in the ovule.
4. This fusion results in the formation of a zygote.

Step 3: Fate of ovules after fertilisation:
- The ovules transform into seeds.
- Each fertilized ovule contains a zygote that develops into an embryo, which is enclosed in a protective covering to become a seed.

Step 4: Fate of ovary after fertilisation:
- The ovary of the flower develops into a fruit.
- The outer wall of the ovary becomes the fruit wall (pericarp), which encloses the seeds.

Step 5: Conclusion:

Fertilisation: The process of fusion of the male gamete (pollen) with the female gamete (ovum or egg) to form a zygote.

Fate after Fertilisation:
Ovules: Develop into seeds.
Ovary: Develops into the fruit.

Answer 4

Step 1: Understanding the parts of a seed:
A seed contains the embryo, which will grow into a new plant. The main parts of the embryo are:
- Plumule
- Radicle
- Cotyledon

Step 2: Identifying the future shoot:
- The plumule is the part of the embryo that develops into the shoot system of the plant (stem and leaves).
- It grows upward during germination and becomes the future shoot.

Step 3: Identifying the future root:
- The radicle is the part of the embryo that develops into the root system.
- It is the first part of the seedling to emerge during germination and grows downward into the soil.

Step 4: Function of cotyledon:
- The cotyledon acts as a food storage organ in the seed.
- It provides nourishment to the embryo during germination until the seedling can produce its own food via photosynthesis.

Step 5: Conclusion:
- Plumule → Future shoot
- Radicle → Future root
- Cotyledon → Provides food to the embryo during germination