Karnataka Board Class 8 Science Chapter 20 Reproduction in Higher Plants
KSEEB Class 8 Science Chapter 20 Textual Questions & Answers
I. Four alternatives are given to each of the following- incomplete statement / question. Choose the right answer.
Seed develops from.
(d) Embryo sac.
Colour of right blooming flower is usually.
The correct sequence of reproductive stages, seen in flowering plants is.
(a) Gametes, zygote, embryo, seedling.
(b) Zygote, gametes, embryo, seedling.
(c) Seedling, embryo, zygote, gametes.
(d) Gametes, embryo, zygote, seedling.
(a) Gametes, zygote, embryo, seedling
The anther contains.
(b) Female gametes
(c) diploid cells
(d) Pollen grains.
(d) Pollen grains
II. Fill in the blanks with suitable words:
Flowers with blue petals, nectar and strong scent are most likely pollinated by ……………..
Variations in the off springs is the characteristic of ………………. reproduction.
There is much wastage of pollen grain in ………………. pollination.
Fertilization leads to the formation of ………….
III. Answer the followings:
What is reproduction?
Reproduction is one of the basic characteristics of living organisms by which they continue their progeny.
What is sexual reproduction?
The Reproduction which involves the formation and fusion of male and female gametes is called sexual reproduction.
What is pollination?
The process of transfer of pollen grains from the anther to the stigma is called pollination.
Are insects friend of farmers? Explain.
In most plants cross pollination is brought about with the help of insects like butterflies, moths and bees. Cross pollination has many advantages to plants also. Therefore it is considered that insects are friend of farmers.
Draw the diagram of a typical flower and label the parts.
KSEEB Class 8 Science Chapter 20 Additional Questions & Answers
Name the two basic types of reproduction?
There are two basic types of reproduction.
- Asexual Reproduction and
- Sexual Reproduction.
What are gametes?
Sexual reproduction involves the formation and fusion of specialized reproductive cells are called gametes.
Name the reproductive part of the plant.
Flower is the reproductive structure of a plant.
What is pollination? Mention the types of pollination?
The process of transfer of pollen grains from the anther to the stigma is called pollination. There are two typers of pollination
- Self pollination
- Cross pollination
What is Self pollination?
If the pollen grains get transferred to the stigma of the same flower. It is called self pollination.
What is cross pollination?
If the pollen grains get transferred to the stigma of another flower in another plant of the same species, it is called cross pollination.
Explain the structure of a typical flower.
Flower is the reproductive structure of a plant.
- Generally the flower arises from the axil of a leaf, called bract.
- The flower is generally bone on a stalk called pedicel.
- Calyx is the outer most whorl composed of green colored units called sepals.
- Corolla is the second whorl from outside. It is composed of usually brightly colored units called petals.
- Androecium is the third whorl. It is composed of male reproductive structure called stamens.
- The inner most whorl is called gynoecium it is composed of female reproductive structure called carpels.
- A middle elongated style and terminal sensitive region called stigma.
- Ovary encloses the ovules, In the ovule female gametes, ova are formed.
Mention the agents of cross pollination.
The agents of cross pollination are, wind, water and animals.
Write the example for wind pollination plants.
Sugarcane, Maize, and grass are common examples of wind-pollinated plants.
Write the special features of wind-pollinated flowers.
Special features of wind-pollinated flowers are.
The flowers are generally small and dull colored. They produce a large number of the dry and light pollen grain.
Ex: Sugar cane, Jawara, etc.
Explain cross-pollination occurs in aquatic plants.
In aquatic plants generally, we see the formation of separate male and female flowers. Male flower detaches from the plant, float on the surface. The female flowers remain attached to the plant. Male flowers are carried towards the female flowers by the water current. Where they release pollen grains,
Ex: Valisneria, Hydrilla, and Elodea.
Explain the modification of the insect-pollinated flowers.
In most plants, cross-pollination is brought about with help of insects. Like butterflies, moths, and bees. Such flowers show certain modifications to attract insects. These modifications are “mainly concerned with the color of the petals, some flowers contain glands called nectaries which produce the nectar to attract the insects, that bring about cross pollination, flowers which open during the night, usually have a dull coloration, but have an aromatic smell that attracts insects.
What is fertilization? Explain.
Fertilization is the fusion of haploid male gamete in the pollen grain with the haploid female gamete in the ovule. To bring about fertilization, the pollen grain which get deposited on the stigma of the carpel must penetrate the style and reach the ovule. Hence it produces a projection called pollen tube which grows through the length of the style and finally reaches the ovule.
The pollen tube contains male gamete inside the ovule, there is a structure called embryo sac which encloses the female gamete, the pollen tube reaches the embryo sac. Then male gamete in pollen tube and female gamete in embryo sac unite, thus fertilization takes place resulting in the formation of a diploid cell called a zygote.
What are the changes that take place in the flower after pollination and fertilization?
- The following changes take place after the fertilization.
- The diploid Zygote develops into an embryo .which later differentiates into a seed, which later grows into a new plant.
- Surrounding the embryo a nutritive tissue called endosperm is formed.
- The entire ovule now becomes the seed.
- The coverings to the ovule transform into the seed coat.
- The ovary portion of the carpel gets transformed into the fruit enclosing the seed.
- Petals, sepals, and other parts of the flower fall off.
- Thus pollination and fertilization result in the formation of seed. Which is enclosed in the fruit?
Define the following.
- Pulses: Pulses are the principal sources of proteins.
- Pod: The pulses are primarily seeds occurring in variable size and colors inside a type of fruit called a pod.
- Grains: Grains are small, hard dry seeds with or without the fruit wall attached. Most of the grains are generally described as cereals.
- Poaceae: the plants produced primarily by varieter of grasses belonging to the family called Poaceae.
Ex: Maize, rice, wheat, barley, oats.
- Millet’s: Millet’s are coarse grains where the protein content is said to be higher.
Ex: Jowar, bajra, ragi.
What are the main characteristics of Angiosperms?
The seed is enclosed in the fruit. This is a characteristic feature of angiosperms.