NIOS Class 12 Biology Chapter 19 Solution – Reproduction in Plants
NIOS Class 12 Biology Solution Chapter 19 Reproduction in Plants . NIOS Class 12 Biology Chapter 19 Question Answers Download PDF. NIOS Class 12 Biology Notes.
Board |
NIOS |
Class |
12th (Higher Secondary) |
Subject |
Biology |
Topic |
Question Answer, Solution, Notes |
INTEXT 19.1
1.) Define reproduction.
Ans: The process by which living organisms produce their offsprings for the continuity of the species. One of the most crucial traits of all living things is the ability to reproduce. The act of producing one’s own species. For the survival of the species on earth, it is essential.
2.) How is asexual reproduction different from sexual reproduction
Ans: offsprings are produced from a vegetative unit formed by a parent without any fusion of gametes or sex cells and only single parent is required , while in sexual reproduction involves fusion of male and female reproductive cells (gametes) which are haploid and are produced by male and female reproductive organs. This fusion is known as fertilization
3.) What is a gamete?
Ans: Male and female reproductive cells are known as gametes.
4.) Name two types of vegetative reproduction.
Ans : : Vegetative reproduction involves formation of new plantlets from vegetative (somatic) cell, buds or organs of the plant. Fission, budding, fragmentation are the type of it.
5.) Choose the correct option
Apomixis is:
(a) Development of plants in darkness
(b) Development of plants without fusion of gametes
(c) Inability to perceive stimulus for flowering
(d) Effect of low temperature on plant growth
Ans: (b) Development of plants without fusion of gametes
INTEXT 19.2
l.) Define the term isogamy. Which species of Chlamydomonas exhibits isogamy.
Ans: In Isogamy ,the gametes are morphologically identical in structure but differ physiologically or chemically. Isogamy is exhibited by Chlamydomonas eugametos and C. eherenburgii
2) Where does meiosis occur in Chlamydomonas ?
Ans: Meiosis occur in Chlamydomonas in Zygote
3.) Give the method of asexual reproduction in Chlamydomonas. What is the function of zoospores in Chlamydomonas.
Ans: Chlamydomonas is a haploid unicellular alga found in fresh water ponds . Asexual reproduction takes place with the help of zoospores, aplanospores or hypnospores depending upon the availability of water for swimming. Each zoospore develops a cell wall and grows into an adult cell
4.) Name the speicies of Chlamydomonas that reproduces by Anisogamy and the species that reproduces by Oogamy.
Ans: The speicies of Chlamydomonas that reproduces by Anisogamy is C. braunii and the species that reproduces by Oogamy are C.oogamum and C. coccifera
5.) Define the term zoospore and aplanospore
Ans: Zoospore is the name for an asexual, thin-walled flagellate reproductive unit. A zoospore is referred to as an aplanospore if it loses its flagella and stops moving.
INTEXT 19.3
1.) Vegetative reproduction in Spirogyra takes place by means of
Ans: . Vegetative reproduction in Spirogyra takes place by means of Fragmentation
2.) Name the kind of sexual reproduction that occurs in Spirogyra.
Ans: the kind of sexual reproduction that occurs in Spirogyra is Scalariform Conjugation
3.) When does meiosis occur in Spirogyra ?
Ans: The diploid nucleus divides into four haploid nuclei by meiosis when suitable conditions resume.
4.) How many filaments are involved in lateral conjugation ?
Ans: Only one filament is involved in lateral conjugation
INTEXT 19.4
1.) Define the terms (i) Annual- Annual plants, like peas, are those that complete their life cycle from flowering to seed production in a single growing season.
(ii) Biennia – Plants which complete their life cycle in two seasons are called biennials. In the first season these plants remain in the vegetative state, and in the second season, they produce flowers, fruits, and seeds and then die e.g. radish.
(iii) Perennial – Perennials are plants that thrive for numerous years. They may grow through a one- to several-year vegetative phase before beginning to annually produce blooms, fruits, and seeds, such as mangoes.
2.) List the factors which induce flowering
Ans: Temperature, light – day length are the factors which induce flowering
3.) Give one example where external application of hormone can reverse the sex of a flower
Ans: Cannabis
4.) Name the essential whorls in a flower
Ans: Stamens and carpels are the essential whorls in a flower
INTEXT 19.5
1.) What is the innermost wall layer of microsporangium called?
Ans: Tapetum
2) Name the organ where pollen grains are formed. Heredity
Ans: Organ where pollen grains are formed in pollen sac
3.) Name the two layers of pollen grain Exine and and intine
Name two parts of a mature ovule.
4.) Ans: Nucellus and integuments are the parts of a mature ovule.
INTEXT19.6
1.) What is pollination?
Ans: When mature pollen grains, released from anther, are carried to stigma of a flower of the same or different species, it is called pollination. It is of two types ie.,self pollination and cross pollination .
2.) Mention suitable terms for the following :
(i) Flowers do not open and get self-pollinated.
Cleistogamy
(ii) Male and female reproductive organs mature at different times.
Dichogamy
2.) Give two features of insect pollinated flower
Ans: (i) Flowers are large, coloured and showy.
(ii) Some flowers secrete nectar.
INTEXT 19.7
1.) Which part of the ovule forms the seed coat ?
Ans: Integuments of ovule forms the seed coat
- ) Define a seed.
Ans: The seed is defined as a ripened ovule. It contains embryo which develops into a new plant. The seed coat protects the embryo against dehydration and mechanical damage
3.) Give one example of a dicot seed and one of a monocot seed.
Ans: Pea or Gram is a dicot seed and Maize grain is monocot seed.
4.) Define a fruit.
Ans: A fruit is defined as a ripened ovary. It protects seeds and On decay, fruits which contain chemical substances enrich the soil.
5.) List the parts of mature seed.
Ans: Embryo ,Endosperm ,Cotyledons are the parts of mature seed.
6.) Development of an embryo from a cell of embryo sac other than egg is an
example of Adventive Polyembryony
7.) Formation of more than one embryo from a single zygote is called Cleavage Polyembryony
INTEXT 19.8
1.) Define vegetative reproduction.
. Ans: Vegetative reproduction is the process of producing new plants from the vegetative portions of an existing plant.
2.) Give an example of each of the following :
(a) rhizome – Ginger
(b) tuber – Potato
(c) bulb – onion
(d) runner – Lawn grass
(e) sucker – mint
3.) Give an example of vegetative reproduction which is carried out by leaves.
Ans: Bryophyllum is a vegetative reproduction which is carried out by leaves
4.) Name two ways by which vegetative reproduction occurs in plants
Ans: Rhizomes and Bulbs are by vegetative reproduction
INTEXT 19.9
1.) What are the various methods which man uses for propagating plants artificially?
Ans: When, the vegetative parts for propagating crops or ornamental plants it is termed as artificial vegetative propagation .Cutting , Grafting , Layering are the various methods which man uses for propagating plants artificially?
2.) Name at least four specialised plant parts which help in vegetative ,propagation.
Ans: Runner ,Tuber , Bulb , Sucker are the specialised plant parts which help in vegetative ,propagation
3.) Write one advantage of vegetative reproduction.
Ans(i) Offsprings identical to parent. The desired varieties can thus be preserved genetically for use
(ii) Food storage organs allow perennation or survival in adverse conditions.
INTEXT 19.10
1.) Give two examples each of plants which are propagated by the following methods:
(a) Cutting
(i) . Croton
(ii) .Money plant
(b) Layering
(i) Jasmine
(ii) Grapevine
(c) Grafting
(i) Rose
(ii) Mango
2.) Name the artificial means of vegetative propagation commonly used in the
laboratory.
.Ans: artificial means of vegetative propagation commonly used in the laboratory. Is micropropogation
3.) Give two examples of plants which are propagated by micropropagation
technique.
Ans: Chrysanthemum, Asparagus are propagated by micropropagation technique.
TERMINAL EXERCISE
1.) Explain the term isogamy taking Chlamydomonas as an example.
Ans: Isogamy is exhibited by Chlamydomonas eugametos. In this the gametes are morphologically identical in structure but differ physiologically or chemically.
2). Describe scalariform conjugation in Spirogyra.
Ans: In Spirogyra , Conjugating filaments produce an appearance of a ladder .The two strands are very near to one another, their cells link up septum to septum and face to face.
3.) Differentiate between annuals, biennials and perennial plants.
Ans: Annual plants are those that complete their life cycle, from flowering through seed production, in a single growing season.
Biennials: The term “biennial” refers to plants that go through their entire life cycle in just two seasons. These plants, such as radish, develop flowers, fruits, and seeds during the second season before going dormant during the first.
Plants that live for numerous years are referred to as perennials. From one to many years may pass during their vegetative stage before they begin to annually produce blooms, fruits, and seeds.
4.) Give significance of pollination.
Ans: 1. It encourages the ovule to transform into a seed and causes fertilisation.
- In the event of cross-pollination, new plant types are created through novel gene combinations.
- Growth hormones are produced by the pollen tube during pollination, which encourages the ovary to develop into a fruit.
5.) Draw a labelled sketch of a mature ovule.
Ans:
Ovule
6). Give a labelled diagram of a mature pollen grain.
Ans:
7). Mention important characteristics in Anemophilous and Hydrophilous plants.
Ans: Characteristics of Anemophilous
(i) Flowers are little and lack colour, nectar, and fragrance.
(ii) To account for loss when pollen grains are blown by the wind to another flower, flowers produce a high quantity of pollen grains.
(iii)The pollen grains are tiny, light, and occasionally endowed with “Wings” .
Characteristics of Hydrophilous
(i) A lot of pollen grains are produced.
(ii) Pollen grains float over surface of water till they rest on the stigma of female flowers e.g. Hydrilla
8). Give the significance of fertilisation.
Ans: fusion of haploid male and female gametes, which are produced by both male and female reproductive organs. Fertilisation is the term for this union.
Encourages the expansion of the ovary, which results in the development of fruit.
The zygote, which is made up of the genes from two separate people, aids in the recombination of characteristics .
9.) Mention the changes that take place when the fruit ripens.
Ans: Fruit undergoes the following changes when it ripens:
(i) Sugar is produced from starch.
(ii) distinct organic substances (esters) can be produced to produce distinct textures, tastes, and flavours.
(iii) The degradation of chlorophyll causes alterations in the colour of the fruit’s skin.
10.) Define the following terms :
(a) Corm : It is the underground modification of stem which are provided with buds which develop into a new plant and are therefore used to carry out vegetative propagation.
(b) Scion : The rooted plant, when used as a stock, is physically strong and disease-resistant. A scion is a branch that is put into this stock.
(c) Callus : The tissue develops into an amorphous lump known as a callus by growing extremely quickly.
(d) Micropropagation: Micropropagation is the process in which plants are propagated using the process of plant tissues culture.
(e) Vegetative reproduction : The growth of new plants from plant tissues other than flowers and seeds is known as vegetative reproduction.
11.) In what ways do plants reproduce vegetatively without human assistance ?
Ans: Plants reproduce vegetatively without human assistance by bulbs, tubers, rhizomes etc
12.) In what ways do plants reproduce vegetatively with human assistance?
Ans: plants reproduce vegetatively with human assistance by artificial vegetative propagation such as cutting , layering , grafting etc.
13.) Define and give an example of each of the following:
(a) Rhizome: Rhizome are the plant which are grow underground and produce shoot and root system
(b) Stolon :Stolen are the stem of plants which grow horizontal to the ground
(c) Cutting : Cutting is the process that involves the part of plants such as stem. Many plants, including roses, can be propagated through stem cuttings. These plants’ cuttings can even be cultivated in water, where they form roots and ad hoc buds.
(d) Layering: In this technique, the developing tip of a plant’s lower branch is left above the dirt and the branch is bent downward and covered with moist soil.
(e) Grafting : For the development of plant kinds without seeds, it is especially important. It entails putting a little branch inside a plant with roots.
14.) What are the advantages and disadvantages of vegetative reproduction ?
Ans: Vegetative reproduction refers to the process of creating new plants from a plant’s vegetative elements.
Advantages
(A) Quick means of reproduction and distribution.
(b) Offspring with identical parents. Thus, the desired types can be used genetically conserved.
(c) Organs for storing food enable persistence or survival under difficult circumstances.
Disadvantages
(A) Crowding and competition for available space, unless forcibly divided.
b) By using this strategy, new kinds can only be created through mutation.
(c) Diseases that are typical of the species spread quickly and may be harmful to a crop.
15.) In what way is vegetative reproduction simple ?
Ans: Vegetative reproduction involves formation of new plantlets from vegetative (somatic) cell, buds or organs of the .
It is simple in many ways such as, desired plants can be produces, a incomplete part can be used for the production, the technique used in the process is simple and easy, large amount of desired offspring can be produce at a time.
16.) Write short notes on
(a) Runner : Runners are stem of a plant which grow along with the ground , which gives rise to roots and branches.
(b) Sucker : suckers are the plants which grow near ground surface horizontally
(c) Bulb : Bulb are utilised for vegetative propagation is the subsurface modification of the stem and bulb (onion), which produces buds that grow into new plants.
(d) Tuber : Tuber are the parts of the plant which grows under the ground .
17.) In brief describe the various steps of micropropagation.
Ans:
- A plant’s little piece of tissue, organ, or even a single cell is removed and moved aseptically into a sterilised container with nourishing medium.
- The tissue develops into a callus, an amorphous mass, very quickly.
- Plantlets (baby plants) are created when hormone-induced differentiation is induced in small amounts of tissue that are transplanted to a new, specialised media.
- The plantlets can gradually be moved into soil or containers as they grow into full plants
19.) What is the significance of micro propagation ?
Ans: By using this technique, it is possible to produce an infinite number of identical plants from a little amount of parent tissue.
In some areas of our country, micropropagation is being successfully explored with orchids, carnations, Chrysanthemum, and asparagus.
20.) If a branch of dasehri mango is grafted on a tree producing desi mango. What type of mangoes will be produced on the grafted branch and on other branches of the tree?
Ans: Grafting is for the development of plant kinds without seeds, it is especially important. It entails putting a little branch inside a plant with roots. Daseheri mango will produce in grafted branch and desi mango will produce on other branches.
Also see: Next Chapter No. 20 Question Answer