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Chapter 3

Reproduction in Plants

Class 8 - Living Science Biology Ratna Sagar


Check your progress 1

Question 1

The reproductive sex cells are known as ............... .

Answer

The reproductive sex cells are known as gametes.

Question 2

Multiple fission occurs in certain algae such as ............... and ............... .

Answer

Multiple fission occurs in certain algae such as Chlorella and Chlamydomonas.

Question 3

............... propagation takes place in plants which do not produce seeds.

Answer

Vegetative propagation takes place in plants which do not produce seeds.

Question 4

............... are the organs of vegetative propagation in potato.

Answer

Eyes are the organs of vegetative propagation in potato.

Question 5

Sugarcane and pineapple plants are grown by ............... method.

Answer

Sugarcane and pineapple plants are grown by Cutting method.

Question 6

In grafting, a stem cutting called ............... from one plant is attached and tied to the rooted stem called ............... of another plant.

Answer

In grafting, a stem cutting called Scion from one plant is attached and tied to the rooted stem called Stock of another plant.

Question 7

............... is also called micropropagation.

Answer

Tissue Culture is also called micropropagation.

Check your progress 2

Question 1

............... protects the flower in the bud stage.

Answer

Calyx (sepal) protects the flower in the bud stage.

Question 2

The male reproductive part of a flower is called ............... .

Answer

The male reproductive part of a flower is called Androecium.

Question 3

Complete flowers are also called ............... or ............... flowers.

Answer

Complete flowers are also called bisexual or hermaphrodite flowers.

Question 4

The single cell formed after fertilization is called ............... .

Answer

The single cell formed after fertilization is called Zygote.

Question 5

The fruit is ripened ............... that contains one or more seeds.

Answer

The fruit is ripened ovary that contains one or more seeds.

Question 6

Water, a suitable temperature and ............... are required for seeds to germinate.

Answer

Water, a suitable temperature and Oxygen are required for seeds to germinate.

Tick the most appropriate answer

Question 1

The simple division of an organism into two smaller daughter cells of roughly equal size is called

  1. binary fission
  2. multiple fission
  3. fragmentation
  4. budding

Answer

binary fission

Reason — Binary fission is the simple division of an organism into two smaller daughter cells of roughly equal size.

Question 2

Which of these can be reproduced by its stem?

  1. carrot
  2. Bryophyllum
  3. rose
  4. papaya

Answer

rose

Reason — By the method of Grafting, rose plant can be reproduced by its stem. It is one of the Artificial Vegetative Propogation methods.

Question 3

An incomplete flower with only androecium is called a

  1. hermaphrodite flower
  2. pistillate flower
  3. bisexual flower
  4. staminate flower

Answer

staminate flower

Reason — Androecium is the male part of the flower. A unisexual flower with only male part is called staminate flower.

Question 4

Flower which have all the four whorls are called

  1. neutral flowers
  2. staminate flowers
  3. incomplete flowers
  4. complete flowers

Answer

complete flowers

Reason — Flowers having all the four whorls i.e., Calyx (sepals), Corolla (petals), Androecium and Gynoecium are called complete flowers.

Question 5

Which of the following is an artificial process?

  1. binary fission
  2. budding
  3. grafting
  4. fragmentation

Answer

grafting

Reason — Grafting is an artificial method of vegetative propagation.

Question 6

In cross pollination, pollen grains from the anther of a flower are transferred to the stigma of

  1. the same flower
  2. another flower on the same plant
  3. flower of another plant of different species
  4. flower of another plant of same species

Answer

flower of another plant of same species

Reason — The process of transfer of pollen grains from the anthers to the stigma of a flower of another plant of the same species is called cross pollination.

Question 7

A pollen tube grows through the

  1. filament
  2. style
  3. anther
  4. ovary

Answer

style

Reason — When a pollen grain reaches the stigma, it begins to grow a pollen tube that travels down through the style to reach the ovules inside the ovary.

Question 8

Seeds are produced from

  1. anthers
  2. ovules
  3. pollen grains
  4. eggs

Answer

ovules

Reason — A seed is a fertilized and mature ovule.

Question 9

Fertilization takes place inside the

  1. ovary
  2. ovule
  3. ovum
  4. gynoecium

Answer

ovule

Reason — When a pollen grain reaches the stigma, it begins to grow a pollen tube that travels down through the style to reach the ovules inside the ovary. A male gamete or male sex cell travels down each pollen tube and fuses with the egg cell (or a female gamete) inside an ovule.

Question 10

A plant embryo consists of

  1. cotyledons and embryonal axis
  2. plumule and radicle
  3. plumule and cotyledons
  4. cotyledons, embryonal axis and radicle

Answer

cotyledons and embryonal axis

Reason — After fertilization, the zygote (fertilized egg) divides and grows into an embryo which has two cotyledons and an embryonal axis.

Fill in the blanks

Question 1

During unfavourable conditions, some organisms develop a thick protective covering called ............... around themselves.

Answer

During unfavourable conditions, some organisms develop a thick protective covering called Cyst around themselves.

Question 2

The small outgrowth arising from the yeast cell is called a ............... .

Answer

The small outgrowth arising from the yeast cell is called a bud

Question 3

The gynoecium consists of ..............., ............... and ............... .

Answer

The gynoecium consists of Stigma, Style and Ovary .

Question 4

Pollination taking place between two flowers present on two separate parents plants is called ............... pollination.

Answer

Pollination taking place between two flowers present on two separate parents plants is called Cross pollination.

Question 5

The process by which a dormant embryo becomes active and grows into a new plant is known as ............... .

Answer

The process by which a dormant embryo becomes active and grows into a new plant is known as Germination.

Write true or false. Correct the false statements.

Question 1

Sexual reproduction involves the fusion of an egg cell and a male gamete.

Answer

True

Question 2

The development of a new plant from the vegetative part of a flowering plant is called fragmentation.

Answer

False

Correct Statement — The development of a new plant from the vegetative part of a flowering plant is called asexual reproduction.

Question 3

A whole new plant can grow from the eye of a potato tuber.

Answer

True

Question 4

Cutting and layering are natural methods of asexual reproduction.

Answer

False

Correct Statement — Cutting and layering are artificial methods of asexual reproduction.

Question 5

A male gamete travels down the pollen tube and fuses with the egg cell inside an ovule.

Answer

True

Define the following terms

Question 1

Multiple Fission

Answer

Multiple Fission — The process of asexual reproduction in which the cell divides repeatedly inside the cyst to produce many daughter cells is called Multiple fission. It is found in unicellular algae such as Chlorella and Chlamydomonas.

Question 2

Budding

Answer

Budding — The process of asexual reproduction in which a small bulb-like outgrowth called bud appears on the body of an organism, develops into a new organism and finally detaches from the parent to lead an independent life is called Budding. Budding is seen in yeast (fungus).

Question 3

Gynoecium

Answer

Gynoecium — The female part of a flower consisting of stigma, Style and ovary is called gynoecium.

Question 4

Vegetative Propagation

Answer

Vegetative propagation — Reproduction in plants wherein a new plant can arise from a vegetative part such as root, stem or leaf without the help of any reproductive organ is called vegetative propagation.

Question 5

Self Pollination

Answer

Self pollination — The process of transfer of pollen grains from the anthers to the stigma of the same flower, or another flower of the same plant is called self pollination.

Question 6

Cross Pollination

Answer

Cross pollination — The process of transfer of pollen grains from the anthers to the stigma of a flower of another plant of the same species is called cross pollination.

Question 7

Fertilization

Answer

Fertilization — The process of fusion of the male gamete with the female gamete is called fertilization.

Question 8

Germination

Answer

Germination — The process by which a sleeping or dormant embryo becomes active and grows into a new plant is known as germination.

Differentiate between

Question 1

Asexual Reproduction and Sexual Reproduction

Answer

Sl.
No.
Asexual ReproductionSexual Reproduction
1.The production of offsprings from a single parent without the fusion of sex cells is called Asexual Reproduction.The production of offsprings due to fusion of male and female sex cells is called Sexual Reproduction.
2.Asexual Reproduction involves only one organism.Sexual Reproduction involves two organisms — male and female of the same species.
3.Offspring have exactly same features as the parent.Offspring has a mix of of features of both parents.

Question 2

Binary Fission and Multiple Fission

Answer

Sl.
No.
Binary FissionMultiple Fission
1.In Binary Fission, a unicellular organism divides into two daughter cells of roughly equal size.In Multiple Fission, a unicellular organism repeatedly divides inside the cyst to produce many daughter cells. Later the cyst breaks open releasing new organism.
2.Two daughter cells are produced.Many daughter cells are formed.
3.Occurs in normal conditions.Occurs in unfavourable conditions.

Question 3

Sexual Reproduction and Vegetative Propagation

Answer

Sl.
No.
Sexual ReproductionVegetative Propagation
1.Reproduction in flowering plants which involves fusion of male and female gametes and seed formation.Reproduction in some flowering plants, in which new plants arise from a vegetative part such as root, stem or leaf etc.
2.The offspring shows variation.Offspring is identical to the parent.
3.Seed is formed and gives rise to a new plantPlant parts like tuber, rhizome, corm, stem, root, leaves etc. are used to grow new plants.

Question 4

Cutting and Grafting

Answer

Sl.
No.
CuttingGrafting
1.In this method, a part of stem with an axillary bud is cut and planted in moist soil.In this method, a stem cutting (scion) from one plant is attached and tied to the rooted stem (stock) of another plant.
2.New plant is identical to parent plant.The plant is superior than both the parent plants.
3.Cutting is used in propagation of Rose, Cacti, Bougainvillea etc.Grafting is used in Rose, Mango, Guava etc.

Question 5

Stamen and Pistil

Answer

Sl.
No.
StamenPistil
1.Stamen is the male part of flower.Pistil is the female part of flower.
2.Stamen consists of anther and filament.Pistil consists of Stigma, Style and ovary.
3.Stamen releases pollen grains.The stigma in pistil receives the pollen grains.

Question 6

Self Pollination and Cross Pollination

Answer

Sl.
No.
Self PollinationCross Pollination
1.It occurs within a flower or between two flowers of the same plant.It occurs between two flowers of different plants of the same species.
2.No external agent of pollination is required.External agents such as wind, water, insects, birds and animals are required.
3.Pollen grains are produced in small numbers, thus, no wastage of pollen grains occurs.Pollen grains are usually produced in large numbers, thus wastage of pollen grains occurs.
4.Flowers are usually not attractive.Flowers are attractive with coloured petals.

Answer in one word

Question 1

The method of reproduction that occurs in Amoeba and Paramecium

Answer

Binary fission

Question 2

An organism that reproduces by spore formation

Answer

Rhizopus (Bread Mould)

Question 3

A plant reproducing by adventitious buds on the margin of their leaves

Answer

Bryophyllum

Question 4

A plant propagated by grafting

Answer

Rose

Question 5

The female reproductive part of a flower

Answer

Gynoecium

Question 6

The result of fusion of two gametes

Answer

Zygote

Answer the following in short

Question 1

Define binary fission.

Answer

The process of reproduction in unicellular organisms by division of their cell into two daughter cells of roughly equal size is called binary fission.

Question 2

What is rhizome ?

Answer

Short, branched, underground stem which has distinct nodes and internodes bearing buds are called rhizome.

Question 3

How do plants such as Bryophyllum propagate?

Answer

Bryophyllum propagates by vegetative propagation in their leaves. They produce adventitious buds at the margin of their leaves. These buds develop into small plantlets under suitable conditions.

Question 4

Write two disadvantages of vegetative propagation.

Answer

Two disadvantages of vegetative propagation are:

  1. All offsprings from the same parent have the same features. So, they are all prone to the same infections, which can result in the destruction of an entire crop.
  2. Over a period of time, newer generations of plants produced via vegetative propagation lose their vigour.

Question 5

What is tissue culture?

Answer

The method of growing plants artificially in a test tube under laboratory conditions is known as Tissue culture.

Question 6

Mention the changes that occur in a flower after fertilization.

Answer

The changes that occur in a flower after fertilization are:

  1. The sepals, petals and stamens fall off.
  2. The stigma and style wither away.
  3. The ovary containing the ovule continues to grow.
  4. Fertilized ovule becomes seed and ovary forms fruit.

Answer the following in detail

Question 1

What is sexual reproduction? What are its advantages?

Answer

Sexual reproduction can be defined as the production of offspring due to fusion of male and female sex cells.

Advantages of sexual reproduction in plants

  1. The offsprings show variations from the parent plants.
  2. They do not lose their vigour after many generations.
  3. They show more resistance to diseases as compared to vegetatively reproduced plants.
  4. Their seeds are dispersed and hence do not cause overcrowding.

Question 2

List the different types of asexual reproduction in plants giving one example of each.

Answer

The different types of asexual reproduction in plants are:

  1. Binary fission and Multiple fission — Euglena and Chlorella
  2. Budding — yeast
  3. Fragmentation — Spirogyra
  4. Spore formation — Rhizopus
  5. Vegetative propagation by natural methods
    1. By underground stem — Potato
    2. By aerial stem — Strawberry
    3. By root — Dahlia
    4. By leaves — Bryophyllum
  6. Vegetative propagation by artificial methods
    1. Cutting — Sugarcane
    2. Layering — Rose
    3. Grafting — Mango
    4. Tissue Culture — Orchids

Question 3

What are the advantages of vegetative propagation?

Answer

The advantages of vegetative propagation are:

  1. Vegetative propagation is faster method of growing plants than growing them from seeds.
  2. Plants produced by vegetative propagation bear flowers earlier than those produced from seeds
  3. Vegetative propagation is extremely useful for production of seedless plants such as banana, grapes and sugarcane.
  4. New plants produced via vegetative propagation are exactly the same as the parent plant and survive even in unfavourable conditions.

Question 4

Describe different types of pollination.

Answer

Pollination can be either Natural or Artificial.

Natural Pollination
Natural Pollination is of two types —

  1. Self pollination — The process of transfer of pollen grains from the anthers to the stigma of the same flower, or another flower of the same plant is called self pollination.
  2. Cross pollination — The process of transfer of pollen grains from the anthers of a flower to the stigma of a flower of another plane of the same species is called cross pollination. Depending on the external agents involved, cross pollination is classified as Pollination by insects(entomophily), Pollination by wind(anemophily), pollination by water(hydrophilly) and Pollination by animals.

Artificial Pollination
Artificial pollination is performed by experts to produce new varieties of plants having desired characteristics. In this process two different varieties of a plant are selected and artificially pollinated to get a hybrid variety of that species. This is called hybridization.

Question 5

Write the features of a flower pollinated by wind.

Answer

Following are the features of a flower pollinated by wind:

  1. Most wind-pollinated flowers are small.
  2. They have dry and light pollen grains which can be easily carried by wind.
  3. Pollen grains are produced in very large quantities so that at least some have a chance to reach the stigma.
  4. The style projects out and has a large, feathery stigma so that the pollen flying in the wind can be easily received.

Question 6

Explain the process of hybridization.

Answer

The process of hybridization is used to produce new varieties of plants with desired characteristics. In this process two different varieties of a crop plant with the desired characteristics are selected. After selection of these varieties, cross-breeding is done by artificial pollination to get a variety of plants which has both the desired characteristics from the parent varieties. This is called hybridization. The new variety formed is called a hybrid.

Correct the sequence

Question 1

Correct the sequence of the following steps to describe the process of fertilization in plants.

  1. The pollen grain begins to grow a pollen tube.
  2. The pollen grain is deposited on the stigma.
  3. The pollen tube grows down through the style to the ovary.
  4. The fusion of the male gamete with the female gamete occurs inside an ovule.
  5. A male gamete travels down each pollen tube.
  6. The nucleus of pollen tube divides to form male gametes.

Answer

  1. The pollen grain is deposited on the stigma.
  2. The pollen grain begins to grow a pollen tube.
  3. The pollen tube grows down through the style to the ovary.
  4. The nucleus of pollen tube divides to form male gametes.
  5. A male gamete travels down each pollen tube.
  6. The fusion of the male gamete with the female gamete occurs inside an ovule.

The Diagram

Question 1

The diagram illustrates the structure of a flower.

The diagram illustrates the structure of a flower. Identify the parts labelled a to e. Which part produces pollen grains? Which part receives pollen grains for pollination? Reproduction in Plants, Living Science Biology Ratna Sagar Solutions ICSE Class 8.
  1. Identify the parts labelled a to e.
  2. Which part produces pollen grains?
  3. Which part receives pollen grains for pollination?

Answer

  1. The parts labelled a to e are:
    a → Petal (corolla)
    b → Stigma
    c → Anther
    d → Ovules
    e → Thalamus
  2. Anther produce pollen grains.
  3. Stigma receives pollen grains for pollination.

Question 2

Draw a labelled diagram to show the process of fertilization in plants.

Answer

The below labelled diagram shows the process of fertilization in plants:

Draw a labelled diagram to show the process of fertilization in plants. Reproduction in Plants, Living Science Biology Ratna Sagar Solutions ICSE Class 8.

Think and Answer

Question 1

To produce a new variety of crop plant with desired characteristics, artificial pollination is required. Why?

Answer

In artificial pollination, two different varieties of a crop plant with the desired characteristics are selected. For example, one variety may be high-yielding (higher-grain producing) and the other variety may be disease resistant. After selection of these varieties, cross-breeding is done by artificial pollination to get a variety of plant which has both the desired characteristics from the parent varieties.

Question 2

Most insect-pollinated flowers produce nectar and are sweet-smelling. Why?

Answer

Most insect-pollinated flowers produce nectar and are sweet-smelling to attract insects. Insects such as bees and butterflies visit different flowers for their food (nectar) and in this process pollen grains get stuck to their body. When they visit another flower, the pollen grains get transferred to the stigma of flowers. Thus, to facilitate pollination by insects (entomophily), most flowers produce nectar and are sweet-smelling.

Question 3

Why are pollen grains produced in large quantities in wind-pollinated flowers?

Answer

In wind-pollinated flowers, pollen grains are produced in very large quantities so that at least some have a chance to reach the stigma.

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