ICSE Class 9 Biology Solutions Chapter 5 Pollination and Fertilization

Class 9th ICSE Biology Solutions Chapter 5 Pollination and Fertilization

Progress Check

Question 1.
Match the items in column I with those in column II

Column I	column II
(i) Feathery stigma hanging out	(a) Rafflesia
(ii) Different timing for maturation of anthers and stigma	(b) Entomophilous
(iii) Pollination by elephant	(c) Wind-pollination
(iv) Flowers produce nectar	(d) Dichogamy

Answer:
(i) – c
(ii) – d
(iii) – a
(iv) – b

Question 2.
Complete the following statements :
(i) Pollination is the process of transference 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 ……………..
Answer:
(i) Pollen grains from anther to the stigma.
(ii) Cross and self-pollination.
(iii) Brightly coloured,
(iv) Anther and stigma.
(v) New.
(vi) Cross, pollen.

Progress Check

Question 1.
Mention if the following statements are true (T) or false (F):
(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 fruit
Answer:
(i) F
(ii) T
(iii) T
(iv) F
(v) T

Review Questions

A. Multiple Choice Type :

Question 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
Answer:
(c) Stigma and anthers mature at the same time

Question 2.
Exine and intine are the parts of
(a) Embryo sac
(b) Pollen grain
(c) Stigma
(d) Seed
Answer:
(b) Pollen grain

B. Very Short Answer Type

Question 1.
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) Fertilization
(e) Integument	(v) Male nuclei
(f) Egg nucleus.	(vi) Rough

Answer:
(a)  -Male nuclei,
(b) – Pollen tube,
(c)  – Rough,
(d) – Endosperm nucleus,
(e) – Testa,
(f)  – Fertilization.

Question 2.
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).
Answer:
(a) butterflies
(b) wind
(c) water.

Question 3.
Fill in the blanks with suitable words.
(a) Transference 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.
Answer:
(a) autogamy
(b) dichogamy
(c) vallisneria.

Question 4.
Name the parts of the ovary which give rise to:
(a) Seed ………………
(b) Fruit ………………
(c) Fruit wall ………………….
Answer:
(a) Seed – Ovules
(b) Fruit – Ovary
(c) Fruit wall – Ovarian wall.

Question 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 flowers 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.
Answer:
(a) bisexual
(b) Inflorescence
(c) Self-pollination or autogamy,
(d) Dichogamy,
(e) Heterostyly,
(f) Entomophily,
(g) Dmithophily.

C. Short Answer Type

Question 1.
Explain the following terms :
(a) Ornithophily.
(b) Elephophily.
(c) Artificial pollination.
Answer:
(a) Ornithophily – Pollination affected by birds.
(b) Elephophily – Pollination affected by elephants.
(c) Artificial Pollination – Pollination affected by man through artificial means

Question 2.
What happens to the following after fertilization?
(a) Ovules
(b) Calyx
(c) Petals
(d) Stamens
Answer:
(a) Ovules – Seed
(b) Calyx – falls of or remain intact in a dried and shrivelled form.
(c) Petals – fall off
(d) Stamens – falls off.

Question 3.
Mention any two contrivances in flowers which favour cross-pollination.
Answer:

1. Unisexuality.
2. Different timing of maturation of androecium and gynoecium.
3. Self-sterility.
4. Structural barriers e.g., pansy flowers.

D. Long Answer Type

Question 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
Answer:
(a) Long and feathery stigma help to trap the pollen-grains in wind-pollination.
(b) Attraction for insects for cross-pollination.
(c) Easily carried by wind to enable cross-pollination.
(d) So that the slightest wind may move them.
(e) Attraction for insects.

Question 2.
Describe the advantages and disadvantages of cross-pollination to the plant.
Answer:
(a) Advantages of cross-pollination

1. The offspring are healthier
2. The seeds produced are abundant and viable.
3. New varieties may be produced by cross-pollination, two different varieties of same species.

(b) Disadvantages of cross-pollination.

1. Pollination is not always certain.
2. The pollen has to be produced in large quantity.
3. 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

Question 1.
What is the function of the pollen tube? Explain it with the help of a diagram.
Answer:
Pollen tube grows out of the pollen-grains by breaking through its exine. The pollen tube grows through the stigma and the style by dissolving the tissues with the help of enzymes and reaches the ovary where it enters the ovule through a minute pore called the micropyle.

Question 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 labelled 1, 2, 3,4 and 5.
(b) Where does the germination of the pollen grain takes place and how?
(c) What ist he function of the part labelled ‘4’?
(d) What happens to the part labelled ‘5’ during the process?
(e) Identify the plant part as a whole
Answer:
(a) (i) Exine,
(ii) Intine,
(iii) Pollen tube,
(iv) Tube nucleus,
(v) Generative nucleus

(b) Pollination.
(c) To direct the growth of pollen tube.
(d) 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.
(e) Mature pollen grain

Question 3.
Given below is a diagrammatic representation of the process of fertilization. Study the same and then answer the questions that follow :

(a) Name the parts labelled 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.
Answer:
(a) (i) Style
(ii) Pollen Tube
(iii) Polar Nuclei
(iv) Ovule
(v) Antipodal cells
(vi) Micropyle

(b) (i) The Ovary becomes the fruit containing the seed inside.
(ii) The Ovule develops into a seed after fertilization.

(c) The degenerating synergids acts as a site of the discharge of the male gametes of the pollen tube,

(d) Stigma is the receptive part of the female reproductive organ on which pollen grains land and germinate.

Additional Questions

Question 1.
Define pollination and fertilization.
Answer:
POLLINATION :
‘The transference of Pollen grains from the anther to the stigma of a flower is called POLLINATION.”
FERTILIZATION :
The fusion of the male gamete with the female gamete (egg) to form the zygote is called a fertilization.

Question 2.
State two advantages of each :
(i) Self pollination
(ii) Cross pollination
Answer:
(i) Two advantages of SELF POLLINATION :

1. It is an economical process as there is hardly any wastage of pollen grains.
2. It is advantageous for improved and high-yielding varieties of crop plants like wheat.

(ii) Two advantages of CROSS POLLINATION :

1. Results in much healthier offsprings which are better adopted to their environment.
2. Hybrids are produced.

Question 3.
State two disadvantages of each :
(i) Self pollination
(ii) Cross pollination
Answer:
(i) Two DISADVANTAGES of self pollination :

1. Seeds loose vitality and the offsprings lack vigour.
2. There is no chance or there is little chance for improve¬ment in the next generation.

(ii) Two DISADVANTAGES of cross-pollination.

1. It is uneconomical process as much of the pollen grains may be wasted.
2. It is not always certain, since there is dependence on external pollinating agents.

Question 4.
Give one term for the following :
(i) Pollination brought about by birds.
(ii) A ripened ovary.
(iii) pollination brought about by wind.
(iv) Flower which contains all the four whorls.
(v) Pollination brought about by insects.
(vi) Help cells flanking the egg cells in a mature ovule.
Answer:
(i) Ornithophilous
(ii) Fruit
(iii) Anemophilous
(iv) Petunia
(v) Entomophilous.
(vi) Embryo sack.

Question 5.
State the fate of each of the following after fertilisation has been affected :
(i) Ovule
(ii) Ovary wall
(iii) Calyx
(iv) Corolla
(v) Stigma and Style
(vi) Stamens
Answer:
(i) Ovule develops into – SEED
(ii) Ovary wall develops into – FRUIT WALL
(iii) Calyx …………….. – WITHERS away
(iv) Corolla …………… – WITHERS away
(v) Stigma and Style …………….. – WITHERS away
(vi) Stamens ……………. – WITHERS away

Question 6.
Briefly explain the following terms :
(i) Double Fertilisation
(ii) Artificial pollination
Answer:
(i) DOUBLE FERTILISATION :
“In flowering plants, two sets of fertilisation takes place. One occurs between the sperm, nucleus and the egg cell, while the other takes place between the second sperm cell and the definitive nucleus. Thus, fertilisation in flowering plants is referred to as DOUBLE FERTILISATION.

(ii) ARTIFICIAL POLLINATION :
“The anthers of young flowers are removed and then these flowers are pollinated with pollen from plants of the desired variety. This is done to get new desired varieties of plants. This type of pollination is called ARTIFICIAL POLLINATION.”

(iii) INCOMPATIBILITY :
In cross pollinated plants, the pollen from a certain species often reaches the stigma of different species. However, the chemicals present in the stigma fail to stimulate the growth of the pollen tube and hence no fertilisation occurs between the plants of different species.

(iv) TRIPLE FUSION :
During the process of fertilisation “The fusion of male gamete with the two polar nuclei is often termed as TRIPLE FUSION.”

• FERTILISATION :
  “Is the fusion of the nuclei of male and female gametes to form a zygote”
• ZYGOTE develops into the EMBRYO, while THE ENDO-SPERM nucleus develops into the ENDOSPERM of the SEED.
• All animals produce specialised and sharply distinct FEMALE and MALE GAMETES.
• MALE GAMETES : Comparatively small, tailed sperms, active motile,
• FEMALE GAMETES : Eggs relatively large, immobile except as they may be passively moved by surrounding fluid.

Question 7.
(a) What is meant by sexual reproduction?
(b) Name the two parts of a flower that are directly concerned with reproduction.
(c) State the role of petals and sepals in reproduction.
Answer:
(a) Reproduction by fusion of gametes to form zygote from
which new individual develops. This type of reproduction involves the union of male and female gametes.

(b)

1. Androecium (stamens)
2. Gynoecium (pistil)

(c) Sepals and petals are non-essential whorls and only help in the process of reproduction by attracting insects for pollination.

Question 8.
In the space provided below, make a neat sketch of the parts named in (b).

Label the following in the above diagrams and state the function of each :
(i) Anther
(ii) Stigma
(iii) Style
(iv) Ovary
Answer:
(i) Anther :
The anther consists of two lobes, each of which has two chambers called Pollen Sacs. Each chamber is filled with pollen grains which vary in size from 10 to 200 m.

(ii) Stigma :
Is the terminal knob-like part of carpel, sticky and forms the landing stage for pollen grains.

(iii) Style :
Is the tubular stalk connecting the stigma and the ovary.
(iv) Ovary :
Is the swollen, basal part of the carpel which con-tains one or more rounded, egg-like structures called ovules.

Question 9.
Fill in the blanks :
(i) The chambers of the anther lobes are called ……………….
(ii) Each pollen has two coats …………… add …………….
(iii) Each member of the gynoecium is called ………………
(iv) The ovules are attached to the ……………..
(v) The ……………. is composed of sepals. Being green, it also manufactures food by ………………..
Answer:
(i) The chambers of the anther lobes are called Pollen Sacs.
(ii) Each pollen has two coats the exine and the intine,
(iii) Each member of the gynoecium is called Pistil.
(iv) The ovules are attached to the Placenta.
(v) The Calyx is composed of sepals. Being green, it also manufactures food by Photosynthesis.

Question 10.
(a) What is meant by pollination?
(b) Name the two types of pollination.
(c) Which of the types named above is the more economical process? Why?
(d) Name the type of pollination in which :
(i) Purity is maintained.
(ii) New varieties are formed.
(iii) Healthier offsprings are formed.
(iv) Seeds are more viable and abundant.
(v) The possibility of pollination is greater.
Answer:
(a) “Is the transference of pollen grains from the anther of a flower to the stigma of a flower.”

(b)

1. Self pollination
2. Cross pollination.

(c) Self pollination is more economical as there are hardly any wastage of pollen grains and are produced in small
quantities. No external pollinating agent is required.

(d) (i) Self pollination.
(ii) Cross pollination.
(iii) Cross pollination.
(iv) Cross pollination.
(v) Self pollination.

Question 11.
(a) What is artificial pollination?
(b) State the significance of artificial pollination.
Answer:
(a) Artificial pollination is a practice adopted by Scientists to evolve new varieties of plants. The anthers of young flowers are removed and flowers are covered by plastic bags. These flowers are then pollinated with the pollen from plants of the desired variety.

(b) To produce new varieties of plant, with desired characteristics and disease resistant varieties.

Question 12.
Give the scientific term for the following :
(i) Wind pollinated flowers.
(ii) Insect pollinated flowers.
(iii) Bird pollinated flowers.
(iv) Water pollinated flowers.
Answer:
(i) Anemophilous
(ii) Entomophilous
(iii) Ornithophilous
(iv) Hydrophilous.

Question 13.
State three characteristics of each :
(a) Wind pollinated flowers.
(b) Insect pollinated flowers.
(c) Give two examples of each of the following :
(i) Insect pollinated flowers.
(ii) Wind pollinated flowers.
(iii) Water pollinated flowers.
Answer:
(a)

• Pollen grains are smooth and light to he carried easily.
• Stigmas are large, feathery and hang out of flower.
• Flowers are small, usually not coloured often green.

(b)

• Pollen grains are sticky or spiny and are produced in smaller quantity.
• Flowers are generally scented and produce nectar.
• Flowers are large and showy to attract insects.

(c) (i) China Rose, Pea, Sun flower, Petunia
(ii) Rice, Wheat, Pine, maize
(iii) Hydrilla, Vallisnaria.

Question 14.
Define fertilisation.
Answer:
“Is the union of nuclei of male and female to form a Zygote from which new individual develops.”

Question 15.
Label the parts indicated by guidelines and state the function of each.

Answer:
Nucellus –
Nutritive tissue living the interior of the ovule.

Embryo-Sac –
It contains the egg cells, antipodal cells and polar nuclei (definitive). Synergids are the cells flanking the egg cell.

ENDOSPERM NUCLEUS –
Secondary nucleus forms it.

Integuments –
Are protective coatings.

Micropyle –
Opening through which the pollen tube enters.

Question 16.
Explain briefly why fertilisation in flowering plants is referred to as double fertilisation.
Answer:
Inside the ovule, the pollen tube releases two male gametes into the embryo sac. One male gamete fuses with one cell of sac to form Syngamy (Zygote), the other male gamete fuses with two polar nuclei called Triple fusion. Thus inside the each embryo sac two fusions, Syngamy and Triple fusion take place. This mechanism of two fusions occurring in an Embryo sac is called DOUBLE FERTILISATION.

Question 17.
(a) Name the part that develop from the following after fertilisation :
(i) Oospore
(ii) Ovule
(iii) Ovary
(iv) Endosperm nucleus
(b) What is the fate of the calyx, corolla, stigma, style and stamens after fertilisation?
Answer:
(a) (i) Embryo
(ii) develops into seed
(iii) fruit
(iv) Endosperm.

(b) Calyx, corolla, stigma, style and stamens all wither away after fertilisation only calyx may some times persist.

ICSE Class 9 Biology Solutions