Question 1

Question 1Distinguish between the following pairs:(a) Autogamy and Geitonogamy(b) Homogamy and Dichogamy(c) Protandry and Protogyny(d) Entomophilous and Anemophilous flowers(e) Advantages of self and cross-pollination

Accepted Answer

(a) Difference between Autogamy and Geitonogamy:AutogamyGeitonogamyIt refers to transfer of pollen grain from anther to stigma of the same flower.It refers to transfer of pollen grain from anther of one flower to stigma of another flower of the same plant.(b) Difference between Homogamy and Dichogamy:HomogamyDichogamyMaturity of anther and stigma of a flower at same time to ensure self pollination.Maturity of anther and stigma of a flower at different times to ensure cross pollination.(c) Difference between Protandry and Protogyny:ProtandryProtogynyAnthers of the flower matures earlier than the stigma.Stigma of the flower matures earlier than the anthers.(d) Difference between Entomophilous and Anemophilous flowers:Entomophilous flowersAnemophilous flowersFlowers that are pollinated by insects are called entomophilous flowers.Flowers that are pollinated by winds are called anemophilous flowers.Flowers are showy.Flowers are not showy.Pollen is produced in limited amount.Very large quantity of pollen is produced.Pollen grains are sticky or spiny.Pollen grains are light dry and smooth.(e) Difference between advantages of self and cross-pollination:Advantages of Self-pollinationAdvantages of Cross-pollinationParental characters are preserved indefinitely.There are variations in character leading to production of new varieties.It is much surer in bisexual flowers where stamens and carpels mature at the same time.The seeds produced are abundant and viable.There is no wastage of pollen grains.Offsprings are healthier and can adapt to environmental changes.

Question 2

Question 4What is the function of the pollen tube? Explain it with the help of a diagram.

Accepted Answer

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 reaches the ovary, where it enters the ovule through a minute pore called the micropyle.

Question 3

Question 1(vii)Bright, showy and nectar producing flowers are needed for pollination to occur by:WindWaterInsectsElephant

Accepted Answer

InsectsReason — Bright, showy and nectar producing flowers attract insects.

Question 4

Question 1(viii)The male inflorescence of maize plant is termed as:CobEarTasselSilk

Accepted Answer

TasselReason — Tassel is the male inflorescence of maize plant.

Question 5

Question 1(ix)Wing and keel petals are found in the flowers of:Pea plantsVallisneriaMaize plantsDahlia

Accepted Answer

Pea plantsReason — Wing and keel petals of pea plant help in pollination by insects.

Question 6

Question 1(x)Which of these does not belong to the embryo sac of a flower?Generative nucleusAntipodal cellsPolar NucleiSynergids

Accepted Answer

Generative nucleusReason — Embryo sac contains one egg cell, two synergids, three antipodal cells, one large central cell. Generative nucleus is present in pollen grain.

Question 7

Question 1(xi)A biology teacher asked her students to mention two conditions that favour cross-pollination.Atul said: Herkogamy and Heterostyly.Ritu said: Bisexuality and self-sterility.Rahul said: Homogamy and Herkogamy.Anaya said: Unisexuality and Dichogamy.Who were correct?Atul and AnayaAtul and RituAnaya and RahulRitu and Rahul

Accepted Answer

Atul and AnayaReason — Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of a flower on a different plant. Adaptations for cross pollination are: -Herkogamy – Physical barrier between anther and stigma.Heterostyly – Styles and stamens of different lengths in flowers.Unisexuality – Male and female flowers on different plants.Dichogamy – Anthers and stigma mature at different times.

Question 8

Question 1(xii)Look at the table given below and identify the kind of pollination that usually occurs in the flower mentioned.FlowerKind of pollinationHibiscusPHydrillaQWheatRP — Entomophily, Q — Hydrophily, R — AnemophilyP — Hydrophily, Q — Elephophily, R — AnemophilyP — Ornithophily, Q — Anemophily, R — ElephophilyP — Ornithophily, Q — Hydrophily, R — Entomophily

Accepted Answer

P — Entomophily, Q — Hydrophily, R — AnemophilyReason — Flower of Hibiscus are large, colorful and scented which attracts insects, hence pollination is by insects (Entomophily).Hydra is an aquatic plant so pollination happens via water (Hydrophily).Flower of wheat are small, non-showy hence pollens are carried by wind (Anemophily).

Question 9

Question 2Given 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 take place and how?(c) What is the function of the part labelled '4'?(d) What happens to the part labelled '5' during the process?

Accepted Answer

(a) The parts labelled 1, 2, 3, 4 and 5 are:1 → Exine2 → Intine3 → Pollen tube4 → Tube nucleus5 → 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.

Question 10

Question 3Given 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?

Accepted Answer

(a) The parts labelled 1, 2, 3, 4, 5 and 6 are:1 → Style2 → Pollen tube3 → Polar nuclei4 → Embryo sac5 → Antipodal cells6 → Micropyle(b) After fertilization, the ovary enlarges to form the fruit and the ovarian wall forms the fruit wall. The ovule becomes the seed.(c) Synergid cells are two small, specialized cells found in the embryo sac adjacent to the egg cells in the female gametophyte of a flowering plant. It nourishes the ovum and plays an important role in guiding the pollen tube. These structures are key for cessation of pollen tube growth and in the release of the sperm cells.(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 fertilization of the egg cell.

Question 11

Question 5Match the items in Column A with those in Column B.Column AColumn BGenerative nucleusPollen tubeGerm poreEndosperm nucleusExineTestaSecondary nucleusFertilizationIntegumentMale nucleiEgg nucleusRough

Accepted Answer

Column AColumn BGenerative nucleusMale nucleiGerm porePollen tubeExineRoughSecondary nucleusEndosperm nucleusIntegumentTestaEgg nucleusFertilization

Question 12

Question 6Give one word/term for the following:A flower containing both male and female parts.Arrangement of flowers on a twig/stem.When pollen grains of a flower reach the stigma of the same flower.When maturation time of reproductive parts in a flower is different.When stigma and anthers do not grow up to same height, What favours only cross pollination ?.Pollination of flowers by insects.Pollination of flowers by birds.

Accepted Answer

Bisexual flowerInflorescenceSelf-pollination/AutogamyDichogamyHeterostylyEntomophilyOrnithophily

Pollination and Fertilization

Long Answer Type

Multiple Choice Type

Structured Application Skill Type

Very Short Answer Type