Selina Concise Class 8 Biology Solution Chapter No. 2- ‘Reproduction in Plants’ For ICSE Board Students.
Multiple choice questions
1.) a.) Pollen is produced in the
i) Filament
ii) Style
iii) pistil
iv) anther
Ans. The anther is a bilobed structure which has pollen grains in it but usually stamen is responsible for pollen production.
2) Reproductive whorls of the flower are
i) Stamens and carpels
ii) Sepals and petals
iii) Sepals and stamens
iv) Petals and carpels
Ans. Stamens contain anther and filament whereas carpel contains style, ovary and stigma.Therefore stamen and carpel are reproductive whorls of the flower.
c.) Grafting is a method of
i) Artificial vegetative propagation
ii) Sexual reproduction
iii) Artificial pollination
iv) Cross pollination
Ans. Artificial vegetative propagation methods are cutting, grafting and layering.
Short Answer Questions
1.) Write two ways in which pollination may occur in plants.
Ans. The two ways in which pollination may occur in plants are Self- pollination and cross- pollination.
2.) Name three agents of pollination.
Ans. The three agents of pollination are a) Wind b) water and c) Insects.
3.) Give two features of flowers that favor pollination by insects.
Ans. i) The flowers which are large with colored petals are able to attract insects.
ii) The flowers are scented or having a fragrance so that the insects locate the flowers by smell.
4.) Name any two characteristics of flowers in which pollination occurs by wind.
Ans. i) The flowers produce large quantity of pollen.
ii) The pollen grains are light so that they are easily carried away.
5.) Fill in the blanks by selecting suitable words.
(unisexual, fertilization, fruit, stamen, anther, bisexual, pollination, seed, ovary)
a) A flower that bears both male and female parts is known as bisexual
b) A flower bearing one male or female parts is known asanunisexual
c) Transfer of pollen grains from anther to stigma is known as
d) Fusion of male cell with female cell is called
e) The ovule develops into an
f) The ovary of the flower develops into a
Long Answer Questions
1.) What is vegetative reproduction?
Ans. Vegetative propagation can be defined as the type of asexual reproduction. The vegetative parts of the plants can give rise to new part or complete plant. In case of damage to plant regeneration can occur. These vegetative reproduction technique produces genetically identical plants with their parents. Such method gives rise to genetical similarity. The vegetative propagation common in most of the aquatic plants and terrestrial plants.
2.) Briefly explain why a gardener prefers to grow certain parts vegetatively?
Ans. The advantages of growing certain parts of the plant vegetatively are:
i) Reproduction by vegetative parts requires very short time to grow.
ii) In less time more quantity of the plants can be produced.
iii) It is an accurate method of propagation.
iv) All the good characters of the mother plant are retained or recieved by the daughter plants.Therefore they have 100 % similarity.
So, theses are the reasons due to gardeners prefers to grow certain parts vegetatively.
3.) Why is it disadvantageous to grow plants vegetatively?
Ans: Yes, there are many disadvantages to grow plants vegetatively such as
(a) The plants which are vegetatively propagated having 100 % similarity or they are genetically identical to each other, so if any infectious agent exposed to in farm, it’ll damage the all plants of the farm
(b) The plants dispersion does not occur steadily, it is a slow process and can be dispersed within a limited range in a particular area. This also leads to competition in plants for the purpose of resources.
4.) What is meant by pollination? Explain the structure of a germinating pollen grain with the help of a labelled diagram.
Ans. Pollination can be defined as the process in which the pollen grains from the anthers are transferred to the stigma of the flower of the same species.
Structure of germinating pollen grain: When pollination occurs, after that the process of pollen grain germination starts. When the germination of pollen grains occurs, the pollen grains are reached or travels up to the stigma of the flower. Then the nucleus which are present in pollen grain are reproduce by the mitosis and divides to form two nucleus. These two nucleus are called as two male gametes. This two male gametes through the pollen tube enters into embryo sac and germination of pollen grain occurs.
5.) Imagine all the seeds produce by a plant happen to fall under the same plant and sprout into new plants. Mention any two problems that will be faced by the new plants.
Ans. i) When all the seeds produce by a plant happen to fall under the same plant and sprout into new plants. Then the source requirement by the plants will increase as the number of plants increases. The sources required by plant are nutrients, space and sunlight.
ii) The all new grown plants will require sufficient amount of nutrients. It’ll lead to nutrient deficiency condition in plants.
6.) What is a flower? Draw a neat labelled diagram showing the L.S. of a typical flower.
Ans. The flower is the reproductive part of the plant. It helps in the sexual reproduction in plants. The flower can contain both male reproductive parts and female reproductive parts. The male reproductive parts are anther, filament and stamen, whereas female reproductive part are style, stigma and ovary. The flower is usually made up of 5 whorls such as sepa;, petal, stamen and carpel.
7.) Write short notes on the following:
a) Micropropagation: Micropropagation can be defined as the in vitro technique in which large progeny are produced by using stock plant material by the modern plant tissue culture technique. This method produces disease free plant and have ability of clonal propagation. Therefore produces unlimited clones within a short period of time.
b) Bryophyllum:Bryophyllum are a group of plants that are derived fromthe algal growth. Basically bryo means mosses and phyta means plants. These plants are called as amphibians of the plants. Bryophyllum usually grow in sheddy and moist areas. They are used in various purposes such as medicinal value and to cure various types of diseases.
c) Vegetative propagation: It is one of the method of asexual reproduction. In which any vegetative part of the plant have ability to give rise to new plant. If any plant part is damaged then the regeneration of damaged part can be takes place. The ability to form new plant are present in vegetative part such as root, stem and leaves. They can form unlimited number of plants.
d) Grafting: Grafting is one of asexual method majorly present in most of the plants. It can also be called as artificial method of propagation. In which certain vegetative part of the plant can be propagated and then grow them as a single plant. The part of the plant called as scion. The part of the plant used is usually shoot or stem. By which the whole plant can be produced.
8.) How is artificial pollination useful to plant breeders? Discuss briefly.
Ans. Artificial pollination can be termed as transferring of pollen grains of the same or different flower to the stigma naturally. In which the breederswill select either two different plant with required properties. Then cross breeding can be done between the two plants by the technique artificial pollination. In this selection of male and female plants are carried out. Then the cross pollination carried out. For example: rice, wheat, maize,can be produced by artificial pollination.
9.) With the help of suitable diagrams, describe”
a) Binary fission in plants: Lower organisms like bacteria, reproduce asexually by the method of binary fission. In this method, the nucleus will split or divides into two and then the cells dividein cytoplasm also by ability of forming two small identical cells similar to those of parent cell called the daughter cells.
b) Budding in yeast cell: Budding method is common in yeast. The plant cell producesan outgrowth called a bud. The bud grows to its maximum size, and then gets separated with its daughter nuclei from the parent body to live as an independent life. Then the cycle will become repeated in daughter cells also.
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