Q34. What do you mean by vegetative propagation? Explain with
It is a type of asexual reproduction in which new plants are produced from roots,
stems, leaves and buds. Since reproduction is through the vegetative parts of
the plant, it is known as vegetative propagation. Most yeasts reproduce
asexually by an asymmetric division process called budding. When
water and nutrients are available algae grow and multiply rapidly by
Q35. How plants such as moss and ferns reproduce?
Plants such as moss and ferns also reproduce by means of spores. Spores
are asexual reproductive bodies. Each spore is covered by a hard protective
coat to withstand unfavourable conditions such as high temperature and low
humidity. So they can survive for a long time. Under favourable conditions, a
spore germinates and develops into a new individual.
Q36. How does reproduction take place in yeast?
Yeast is a single-celled organism. The small bulb-like
projection coming out from the yeast cell is called a bud. The bud gradually
grows and gets detached from the parent cell and forms a new yeast cell. The
new yeast cell grows, matures and produces more yeast cells. Sometimes, another
bud arises from the bud forming a chain of buds. If this process continues, a
large number of yeast cells are produced in a short time.
Q37. How does the process of fertilisation take place in flowers?
When ripe pollen from an anther of the same kind of flower catches on the
stigma, each pollen grain sends out a tiny threadlike tube. The tube grows down
through the style and pierces one of the ovules in the ovary. This
pollen tube carries a male gamete to meet a female gamete in an ovule. Two
gametes fuse together to form zygote. The process of fusion of male and female
(to form a zygote) is called fertilisation. The zygote develops into an embryo.
Q38. How the male gamete in the pollen grain reaches the female
gamete present in the ovule?
Generally pollen grains have a tough protective coat which prevents them from
drying up. Since pollen grains are light, they can be carried by wind or water.
Insects visit flowers and carry away pollen on their bodies. Some of the pollen
lands on the stigma of a flower of the same kind. Some
pollen of a flower may lands on the stigma of a flower of a different plant of
the same kind. Pollen grain on the stigma grows a tiny tube, all the way down
the style to the ovary. This pollen tube carries a male gamete to meet a female
gamete in an ovule.
Q39. Show self-pollination and cross pollination via a labelled
Image From NCERT
Q40. Sketch the reproductive parts of a flower.
Image From NCERT
Q41. Describe the various ways by which seeds are dispersed.
Seeds and fruits of plants are carried away by wind, water and animals.
Winged seeds such as those of drumstick and
maple, light seeds of grasses or hairy seeds of aak (Madar) and
hairy fruit of sunflower get blown off with the wind to far away places.
Some seeds are dispersed by water. These
fruits or seeds usually develop floating ability in the form of spongy or
fibrous outer coat as in coconut. Some seeds are dispersed by animals,
especially spiny seeds with hooks which get attached to the bodies of animals
and are carried to distant places. Examples are Xanthium and Urena.
Some seeds are dispersed when the fruits
burst with sudden jerks. The seeds are scattered far from the parent plant.
This happens in the case of castor and balsam.