(i) Vegetative propagation by cutting : Plants like Rose are propagated by cutting method. In this method the stem cutting is taken from the desired plant and plants in the the soil . The stem cuttings soon strike out roots and grow into new plants. This procedure considerably reduces the time required to obtain a mature plant.

(ii) Autogamy : The transfer of the pollen from the anther of a flower to the stigma of the same flower is known as self pollination or autogamy.

(iii) Triple fusion : During fertilisation, the second male gamete fuses with the secondary diploid (2n) nucleus producing a triploid (3n) primary endosperm nucleus. This is called triple fusion because the fusion involves two polar nucli and the male gamete nuclei. 

Advantages of cross-pollination over self-pollination.

(1) It always results in much healthier offspring which are better adapted to changed environment.

(2) Promotes genetic diversity in plants.

(3) Production of hybrid instead of pure lines. 

(4) Helps to eliminate the undesirable characters. 

Physiological changes which occur in the human body during ageing are—

(1) Effects of ageing on the lung function are seen as decreased elasticity of the lung tissue and increased rigidity of the chest wall.

(2) Kidney becomes less efficient at extracting wastes from the blood.

(3) With age, the brain looses some cells and some others become damaged. Memory is slightly impaired. 

(4) Muscle tissue degenerates due to biochemical changes in the muscle fibres and neuromuscular junctions.

(5) Difficulty in sight and hearing.

(6) The bones lose minerals and become less dense with ageing.

(7) Skin becomes dry and wrinkled.

(8) Hair start greying or falling out.

(9) The body’s immune system loses its ability to effectively deal with the antigens.

(10) Blood pressure increases. 

Location : Embryo sac Found in the female plants or in the plant ovule.

Function ; Embryo sac bears both embryo plant and the endosperm after fertilisation.