NCERT Solutions: Class 7 Science Chapter 8 - Reproduction in Plants

(a) vegetative propagation
(b) unisexual flower
(c) pollination
(d) fertilisation
(e) wind, water and animals

Asexual reproduction takes place without seeds and from a single parent. In vegetative propagation, new plants grow from roots, stems or leaves, for example potato from eyes and Bryophyllum from leaves. In budding, a small bud grows on the parent and separates, as in yeast. In fragmentation, the body breaks into pieces and each piece grows into a new organism, as in Spirogyra. In spore formation, spores germinate into new individuals, as in fungi such as bread mould.

Sexual reproduction is reproduction involving male and female gametes. In flowering plants, stamens produce pollen grains containing male gametes and the pistil contains the ovule with the female gamete. After pollination, the male gamete fuses with the female gamete in the ovule. This fusion is fertilisation and forms a zygote, which later develops into an embryo inside a seed.

Asexual reproduction involves only one parent and does not involve fusion of gametes. Sexual reproduction involves male and female gametes, usually from reproductive parts of flowers, and includes fertilisation.

Self-pollination is transfer of pollen grains from the anther to the stigma of the same flower or another flower on the same plant. Cross-pollination is transfer of pollen grains from the anther of one plant to the stigma of a flower on another plant of the same kind.

After pollination, a pollen grain on the stigma forms a pollen tube that grows through the style to the ovule. The male gamete travels through the tube and fuses with the female gamete in the ovule. This fusion forms a zygote, which develops into an embryo.

Seeds are dispersed by wind, water and animals. Light seeds or winged seeds such as drumstick and maple are carried by wind. Floating fruits or seeds such as coconut are dispersed by water. Spiny or sticky seeds may cling to animals and be carried away, while some fruits are eaten and their seeds are later thrown away or passed out. Some fruits burst and scatter their seeds, as in balsam.

Bud - Yeast; Eyes - Potato; Fragmentation - Spirogyra; Wings - Maple; Spores - Bread mould.

(a) (iv) flower
(b) (i) fertilisation
(c) (iv) fruit
(d) (ii) bread mould
(e) (ii) leaves