Explore

02. The Flower

Answers to textbook exercises

Prepared by: learnloophq@gmail.com

Last edited 25 days ago by Learn LoopHQ.

Chapter: 02. The Flower

⁠

Check Point 1

Flowers having both male and female reproductive whorls.

Bisexual flowers

The colourful whorl of the flower that makes the flower attractive.

Corolla

Single unit of male reproductive whorl or androecium.

Stamen

The swollen tip of the pedicel of flower.

Thalamus

The floral whorl that protects other floral whorls in bud.

Calyx

Check Point 2

Transfer of pollen grains from one flower to the other present on different plants is ________.

Cross-pollination

Fusion of male and female cell or gamete is called ________.

Fertilisation

After fertilisation ovary develops into ________.

Fruit

Apple is an example of ________.

False fruit

Check Point 3

The mature ovule that contains the embryo.

Seed

The process by which seeds spread far and wide.

Dispersal

The process of a seed growing into a young plant.

Germination

The fleshy embryonic leaves that store food in the seed.

Cotyledons

A. Multiple Choice Questions

Flowers with either male or the female reproductive parts are called

(a) Unisexual

Accessory whorls of a flower are

(b) Sepals and petals

For insect pollination, the pollen grains are

The process essential for sexual reproduction in plants are

(d) Pollination and fertilisation

The embryo in a seed consists of

(d) Radicle, plumule and cotyledons

Transfer of pollen grains from anther to stigma of same flower is called

(b) Self-pollination

The three conditions necessary for seed germination are

(a) Moisture, oxygen and suitable temperature

A pollen grain encloses

(b) Male gametes

B. Assertion-Reason Type Questions

Assertion [A]: A temperature below moderate level slows down seed germination. Reason [R]: Temperature affects growth rate as well as metabolism of the seed.

(a) Both Assertion [A] and Reason [R] are true.

Assertion [A]: Petals are brightly coloured parts of a flower. Reason [R]: Sepals attract insects for pollination.

Assertion [A]: Hibiscus flower is incomplete. Reason [R]: One or more whorls are absent in an incomplete flower.

(d) Assertion [A] is false but Reason [R] is true.

Assertion [A]: Reproductive whorls in bisexual flowers are androecium and gynoecium. Reason [R]: Androecium is associated with the formation of male gametes (the pollen) and gynoecium with the formation of female gametes (ova).

(a) Both Assertion [A] and Reason [R] are true.

Assertion [A]: Cotyledons serve to prepare food in seeds. Reason [R]: There are two cotyledons in monocot seeds.

(b) Both Assertion [A] and Reason [R] are false.

C. Fill in the blanks with suitable words.

Flower is modified for _shoot_ reproduction.

Brightly coloured flowers are pollinated by _insects_.

During germination of seed, plumule gives rise to the _shoot_ of the young plant.

Seeds develop from _ovules_.

_Bean_ shows epigeal germination.

_Male gametes_ are formed in pollen grains.

Nectar is produced by flower to attract _insects_ for pollination.

D. State whether the following statements are true or false. If false, rewrite the correct form of statements.

Complete flowers are bisexual flowers having all the four whorls.

True

Pollen grains are male gametes and are formed in the stamens.

True

Fertilisation is the fusion of male gamete and female gamete.

True

After fertilisation ovary forms the mature ovule.

False. After fertilisation, the ovary forms the fruit and ovules form the seeds.

Seeds with two cotyledons are called monocot seeds.

False. Seeds with two cotyledons are called dicot seeds.

Plumule part of embryo grows to form shoot and radicle grows into the root of the plant.

True

E. Give one word for the following.

Green leaf-like structures that protect other parts of a flower

Sepals

Ripe ovary

Fruit

Fusion of male and female gametes

Fertilisation

A flower having all the four whorls

Complete flower

Transfer of pollen grains from anthers to the stigma of the same flower

Self-pollination

F. Give reasons for the following.

Flowers that bloom at night have sweet fragrance.

They have sweet fragrance to attract nocturnal insects (like moths) for pollination, as visual cues (bright colours) are not effective in the dark.

Wind-pollinated flowers are small, inconspicuous and have large and feathery stigma.

They are small and inconspicuous because they do not need to attract insects. Their large and feathery stigma provides a wider surface area to efficiently trap airborne pollen grains.

Some flowers produce nectar.

Flowers produce nectar as a sugary reward to attract insects and other animals, which then act as pollinators, helping in the transfer of pollen grains.

Wind-pollinated flowers produce a large number of pollen grains.

Wind pollination is a less efficient process where many pollen grains are lost. Producing a large number of pollen grains increases the probability that at least some will reach a receptive stigma, ensuring successful pollination.

G. Give functions of the following.

Cotyledons

They store food for the developing embryo (in dicots) or help transfer food from the endosperm to the embryo (in monocots) during germination.

Radicle of embryo

It grows downwards to form the root system of the new plant.

Endosperm

It is a tissue that stores food and provides nourishment to the young plant during germination.

Stigma

It is the receptive tip of the pistil, often sticky, designed to capture and hold pollen grains during pollination.

Stamens

They produce and bear pollen grains, which contain the male gametes essential for fertilisation.

Petals

They are typically brightly coloured and often scented to attract insects and other animals for pollination.

Pericarp in fleshy fruits

It protects the developing seeds from environmental damage and, by being attractive and often edible, facilitates seed dispersal by animals.

H. Encircle the odd one out and give reasons for your choice.

Style, ovary, stamens, stigma

Stamens: Style, ovary, and stigma are all parts of the pistil (female reproductive organ), while stamens are part of the male reproductive organ.

Salvia, Dahlia, pea, wheat

Wheat: Salvia, Dahlia, and pea are primarily insect-pollinated (though pea can be self-pollinated), whereas wheat is wind-pollinated.

Cotton, lotus, poppy, sunflower

Lotus: Cotton, poppy, and sunflower seeds are primarily dispersed by wind, whereas lotus seeds are dispersed by water.

Gram, bean, pea, maize

Maize: Gram, bean, and pea are dicotyledonous seeds (having two cotyledons), whereas maize is a monocotyledonous seed (having one cotyledon).

I. Differentiate between the following.

Bisexual and unisexual flower

Bisexual flower: Possesses both male reproductive organs (stamens) and female reproductive organs (pistil) in the same flower.

Unisexual flower: Contains either only male reproductive organs (stamens) or only female reproductive organs (pistil) in the flower.

Androecium and gynoecium

Androecium: The male reproductive whorl of a flower, composed of stamens, responsible for producing pollen grains.

Gynoecium: The female reproductive whorl of a flower, composed of carpels or pistils, containing ovules and responsible for producing female gametes.

Monocotyledonous and dicotyledonous seeds

Monocotyledonous seed: Has a single cotyledon, and food is typically stored in the endosperm. Example: Maize.

Dicotyledonous seed: Has two cotyledons, which often store food and become fleshy. Example: Bean.

Epigeal and hypogeal germination

Epigeal germination: The cotyledons emerge above the soil surface and become green, often acting as initial photosynthetic leaves. Example: Bean.

Hypogeal germination: The cotyledons remain below the soil surface, and the plumule grows directly upwards to form the shoot. Example: Maize.

Fruit and seed

Fruit: A ripened ovary, which typically encloses and protects one or more seeds.

Seed: A fertilised ovule, containing an embryo, from which a new plant can grow.

Fleshy and dry fruits

Fleshy fruits: Have a soft, pulpy pericarp that is often edible. Example: Mango.

Dry fruits: Have a dry, thin, and non-edible pericarp, with the seed usually being the edible part. Example: Pea.

J. Match the columns.

Ovule - (d) Seed

Insect - (e) Cross pollination

Maize - (a) Hypogeal germination

Anthers - (b) Pollen grains

K. Answer these questions.

Want to print your doc?
This is not the way.

Try clicking the ⋯ next to your doc name or using a keyboard shortcut (

CtrlP

) instead.