Selina Concise Class 9 Biology Solution Chapter No. 5 ‘Pollination and Fertilization’ For ICSE Board Students
Pollination and Fertilization
A)
1) Answer: c) Stigma and Anthers mature at the same time.
In the homogamy, the anther and stigma of flower should mature at the same time and it is necessary to ensure self-pollination.
2) Answer: b) Pollen grain
The pollen grain which are mature have double wall in cell. The inner wall is intine and outer wall is exine. So, pollen grain is the correct one.
B.)
a) Butterflies
b) Wind
c) Water
2.)
Column A | Column B (Answers) |
Generative nucleus | v) Male nuclei |
Germ pore | i)Pollen tube |
Exine | vi) Rough |
Secondary nucleus | ii) Endosperm nucleus |
Integument | iii) Testa |
Egg nucleus | iv) Fertilization |
3.)
a) Transfer of pollen grains from anthers to stigma of the same flower is called as Autogamy.
b) Different timings for maturation of gynoecium and androecium, is called Dichogamy.
c) Vallisneria is a water pollinated flower.
4.)
a) Ovule
b) Ovary
c) Ovarian wall
5.)
a) Bisexual flower
b) Inflorescence
c) Autogamy
d) Dichogamy
e) Heterostyly
f) Entomophily
g) Ornithophily
C.)
a) Ornithophily- When flowers of the plant are pollinated by birds then it is known as Ornithophily.
b) Elephophily – Here in the pollination, elephants are responsible.
c) Artificial Pollination- If a man transfers pollen artificially to the stigma then it’s is said to be artificial pollination.
2.)
a) Answer: The ovule becomes seed.
b) Answer: Calyx will fall off or remain intact in a dried form.
c) Answer: Petals generally falls off.
d) Answer: Stamens also falls off.
3.)
Answer:
The following conditions favors cross pollination:
- Unisexuality
- Mechanical barrier
- Self-sterility
- Dichogamy
D.)
1.)
a) Answer: Are to trap the pollen grains in wind pollination.
b) Answer: It helps to attract insects for the cross-pollination.
c) Answer: Light pollen can easy to carry away by wind.
d) Answer: The slightest wind can move them and called as versatile anthers.
e) Answer: Insect attraction for pollination.
2.)
Answer:
Advantages of cross pollination:
- Healthier offsprings.
- Abundant and viable seed which are produced.
- Two different varieties of same species can be produced by cross pollination.
Disadvantages of cross pollination
- Due to pollinating agents, pollination will not be always certain.
- A lot of wastage of pollen occurs due to large quantity of pollen produced by plants.
- This is uneconomical process for the plants due to large and coloured flowers.
E)
1.) Answer:
The stigma and style are the way to grow pollen tube by dissolving the tissues by certain enzymes and reaches ovary. It reaches to the embryo sac and pushes through micropyle.
2.
a) Answer: 1. Exine, 2. Intine, 3. Pollen tube, 4. Tube nucleus, 5. Generative nucleus.
b) Answer:
If pollen grains falls on the stigma of the same plant species then only the pollen grains will germinate. In other cases or otherwise it disintegrates. The falling of pollen grains on stigma is stimulated for the germination due to sugar’s secretion by stigma.
c) Answer:
The part ‘4’ is responsible to direct the growth of pollen tube towards ovary. The ‘4’ part is of tube nucleus.
d) Answer:
The generative nucleus is located at the tip of the pollen tube which divide into two sperm nuclei. It releases two sperm nuclei by entering pollen tube to one of synergids. From these, one sperm fuses with egg cell nucleus which forms zygote. Where the other sperm nucleus moves towards two polar nuclei and fuses with them.
3)
a) Answer:
- Style
- Pollen tube
- Polar nuclei
- Embryo sac
- Antipodal cell
- Micropyle
b) Answer:
After fertilization, ovary becomes large to form the fruit and the wall of ovary forms wall of fruit. Ovule forms seed.
c) Answer:
Following is the function of synergid:
They are responsible for the nourishment of egg cell. It helps pollen grain towards the egg. It also helps in release of sperm nuclei and appropriate functioning of pollen tube.
d) Answer:
When the pollen grains fall on the stigma of the same plant it germinates. After germination process, Pollen tube grows through stigma and style. It reaches to the ovary and fertilizes egg cell.