ICSE Solutions for Chapter 5 Pollination and Fertilization Class 9 Biology Selina
Progress Check
1. Match the items in Column I with those in Column II.
|
Column I |
Column II |
|
(i) Feathery stigma hanging out |
Rafflesia |
|
(ii) Different timings for maturation of anthers and stigma |
Entomophilous |
|
(iii)Pollination by elephant |
Wind pollination |
|
(iv) Flowers produce nectar |
Dichogamy |
Solution
|
Column I |
Column II |
|
(i) Feathery stigma hanging out |
Wind pollination |
|
(ii) Different timings for maturation of anthers and stigma |
Dichogamy |
|
(iii)Pollination by elephant |
Rafflesia |
|
(iv) Flowers produce nectar |
Entomophilous |
2. Complete the following statements:
(i) Pollination is the process of transfer of ____
(ii) The two kinds of pollination are ____ and ____
(iii) For self-pollination the flowers need not be ____ and showy.
(iv) For self-pollination, ____ and ____ must mature at the same time.
(v) Self-pollination does not yield ____ varieties.
(vi) In ____ pollination there is much wastage of ____ .
Solution
(i) Pollen grains
(ii) Cross-pollination and self-pollination
(iii) Large
(iv) Stamens, carpels
(v) New
(vi) Cross, pollen
3. Mention if the following statements are true
(i) Intine is the outer wall of pollen grain.
(ii) Pollen tube enters ovule through micropyle.
(iii) Zygote gives rise to embryo
(iv) Ovule becomes fruit.
(v) Dry sepals may persist in some fruits.
Solution
(i) The statement is false.
(ii) The statement is true.
(iii) The statement is true.
(iv) The statement is false.
(v) The statement is true.
Review Questions
A. Multiple Choice Type
1. Which one of the following is one of the characteristics of self-pollinated flowers?
(a) Flowers are large and showy
(b) Flowers remain closed and do not open
(c) Stigma and anthers mature at the same time
(d) Pollen is produced in very large quantities
Solution
(c) Stigma and anthers mature at the same time
In self-pollination, the stigma and the anther lie close to each other and mature at the same time.
2. Exine and intine are the parts of
(a) Embryo sac
(b) Pollen grain
(c) Stigma
(d) Seeda
Solution
(b) Pollen grain
The mature pollen grain is a cell having double wall — the outer exine and the inner intine.
B. Very Short Answer Type
1. State the name of the chief pollinating agent against the corresponding plant by choosing from those given in brackets.
(a) Dahlia ____ (Crow, butterflies, mosquito)
(b) Maize ____ (Bees, locusts, rain, wind).
(c) Vallisneria ____ (wind, water, ants, rabbits).
Solution
(a) Butterflies
(b) Wind
(c) Water
2. Match the items in column A with those in Column B.
|
Column A |
Column B |
|
(a) Generative nucleus |
(i) Pollen tube |
|
(b) Germ pore |
(ii) Endosperm nucleus |
|
(c) Exine |
(iii) Testa |
|
(d) Secondary nucleus |
(iv) Fertlization |
|
(e) Integument |
(v) Male nuclei |
|
(f) Egg nucleus |
(vi) Rough |
Solution
|
Column A |
Column B |
|
(a) Generative nucleus |
(v) Male nuclei |
|
(b) Germ pore |
(i) Pollen tube |
|
(c) Exine |
(vi) Rough |
|
(d) Secondary nucleus |
(ii) Endosperm nucleus |
|
(e) Integument |
(iii) Testa |
|
(f) Egg nucleus |
(iv) Fertilization |
3. Fill in the blanks with suitable words.
(a) Transfer of pollen grains from anthers to stigma of the same flower is called ____
(b) Different timings for maturation of gynoecium and androecium, is called ____
(c) ____ is a water-pollinated flower.
Solution
(a) Autogamy
(b) Dichogamy
(c) Vallisneria
4. Name the parts of the ovary which give rise to:
(a) Seed ___
(b) Fruit ___
(c) Fruit wall ___
Solution
(a) Ovules
(b) Ovary
(c) Ovarian wall
5. Give one word/term for the following:
(a) A flower containing both male and female parts
(b) Arrangement of flowers on a twig/stem
(c) When pollen grains of a flower reach the stigma of the same flower
(d) When maturation time of reproductive parts in a flower is different.
(e) When stigma and anthers do not grow up to same height, which favours only cross-pollination?
(f) Pollination of flowers by insects
(g) Pollination of flowers by birds.
Solution
(a) Bisexual flower
(b) Inflorescence
(c) Autogamy/self-pollination
(d) Dichogamy
(e) Heterostyly
(f) Entomophily
(g) Ornithophily
C. Short Answer Type
1. Explain the following terms:
(a) Ornithophily
(b) Elephophily
(c) Artificial pollination.
Solution
(a) Ornithophily: The process of pollination affected by birds is known as ornithophily.
(b) Elephophily: The process of pollination affected by elephants is known as elephophily.
(c) Artifical pollination: The process of pollination affected by men through artificial modes is referred to as artificial pollination.
2. What happens to the following after fertilization?
(a) Ovules
(b) Calyx
(c) Petals
(d) Stamens
Solution
(a) Ovules: Ovules become the seed post fertilization
(b) Calyx: After fertilization, the calyx sheds or falls off or remains intact in a shriveled and dried form.
(c) Petals: Post fertilization, the petals shed and fall.
(d) Stamens: Once fertilization takes place, the stamens fall off.
3. Mention any two contrivances in flowers which favor cross-pollination.
Solution
Contrivances in flowers which favour cross-pollination:
(i) Unisexuality
(ii) Different timings of maturation of and roecium and gynoecium
(iii) Self-sterility
(iv) Structural barriers
D. Long Answer Type
1. What are the advantages of the following in the flower to the plant concerned?
(a) Long and feathery stigma
(b) Brightly coloured petals
(c) Smooth and light pollen
(d) Protruding and easily movable anthers
(e) Fragrant nectar
Solution
(a) Long and feathery stigma: Help to trap pollen grains in wind-pollination.
(b) Brightly coloured petals: Attracting insects for cross-pollination.
(c) Smooth and light pollen: Easily carried by wind to enable cross-pollination.
(d) Protruding and easily movable anthers: Even slightest wind can move them.
(e) Fragrant nectar: Attracting Insects for pollination.
2. Describe the advantages and disadvantages of cross-pollination to the plant.
Solution
Advantages of cross-pollination:
(i) The offspring are healthier.
(ii) The seeds produced are abundant and viable.
(iii) New varieties may be produced by cross-pollinating two different varieties of the same species.
Disadvantages of cross-pollination:
(i) Pollination is not always certain.
(ii) The pollen has to be produced in large quantity.
(iii) The process is uneconomical for the plant because the flowers have to be large, coloured, scented and have to produce nectar for attracting pollinating agents.
E. Structured/Application/Skill Type
1. What is the function of the pollen tube? Explain it with the help of a diagram.
Solution
The pollen tube grows out of the pollen grains by breaking through its exine. The pollen tube grows through the stigma and style by dissolving these tissues with the help of enzymes and readies the ovary, where it enters the ovule through a minute pore called the micropyle.
2. Given alongside is a diagrammatic sketch of the sectional view of a germinating pollen grain. Study the same and then answer the questions that follow:
(a) Name the parts labeled 1,2,3,4, and 5
(b) Where does the germination of the pollen grain take place and how?
(c) What is the function of the part labeled ‘4’?
(d) What happens to the part labeled ‘5’ during the process?
Solution
(a) 1 → Exine
2 → Intine
3 → Pollen tube
4 → Tube nucleus
5 → Generative nucleus
(b) Germination of the pollen grain takes place only after it falls on the stigma of the same plant species. The pollen grain is stimulated to germinate due to the secretion of sugars by the stigma.
(c) The function of part '4' (tube nucleus) is to direct the growth of the pollen tube towards the ovary.
(d) During germination of the pollen grain, part '5' (generative nucleus) present at the tip of the pollen tube divides into two sperm nuclei. The pollen tube enters one of the synergids and releases its two sperm nuclei. Of these, one sperm nucleus enters the egg cell and fuses with its nucleus, while the other sperm nucleus moves towards the two polar nuclei in the central cell and fuses with them.
3 Given below is a diagrammatic representation of the process of fertilization. Study the same and then answer the questions that follows:
(a) Name the parts labeled 1,2,3,4, 5 and 6.
(b) What happens to (i) Ovary (ii) Ovule after fertilization?
(c) What is the function of the synergids?
(d) What part does the stigma play in the process of fertilization?
Solution
(a) 1 → Style
2 → Pollen tube
3 → Polar nuclei
4 → Embryo sac
5 → Antipodal cells
6 → Micropyle
(b) After fertilisation
(i) The ovary enlarges to form the fruit and the ovarian wall forms the fruit wall.
(ii) The ovule becomes the seed.
(c) Synerglds help in nourishing the egg cell, guiding the pollen tube towards the egg, proper functioning of the pollen tube and release of sperm nuclei.
(d) Pollen grain is transferred to the stigma during pollination. Germination of pollen grain takes place only if it falls on the stigma. After germination, the pollen tube grows through the stigma and reaches the ovary for the fertilisation of the egg cell.