Germination

Question 1

Germination

Answer 1

the process by whichthe embryonic plant in a seed grows intoa seedling.

Question 2

Seeds require three conditions to germinate:

Answer 2

• Water to activate the enzymes so that chemical reactions can occur.
• Oxygen for aerobic respiration to produce energy.
• A suitable temperature, usually between about 5 °C and 40 °C, to activate enzymes.

Question 3

PROCESS

Answer 3

Water is absorbed through the micropyle which causes the seed to swell and it activates enzymes that breakdown stored food in the cotyledons.
Proteins are broken down into amino acids, starch is broken down into maltose and then glucose, and lipids into fatty acids and glycerol.

These soluble substances are then translocated to the radicle and plumule

• The amino acids are used in making new cells in the tips of the radicle and plumule so thatgrowthcan occur.
• The glucose is used in respiration to produceenergy for the radicle and plumule to grow, and to make the cellulose cell walls of new cells.
• The fatty acids and glycerol are used inrespiration.

As the radicle grows, it emerges from the testa and grows downwards. The plumule then emerges and grows upwards. The cotyledons may be carried up and out of the soil or they may remain below the soil

Question 4

Pollination

Answer 4

the transfer of pollen grains from the male anthers to the female stigmas of flowers.

Question 5

SELF AND CROSS

Answer 5

• Self pollination occurs when a pollen grain is transferred from an anther to a stigma of the same flower or to a stigma of another flower on thesame plant.
• Cross pollination occurs when a pollen grain is transferred from an anther of a flower on one plantto a stigma of a flower on a different plant of the same species.

Question 6

Agents of pollination

Answer 6

carry the pollen grains between flowers. They may be thewind, insects and somebirds, e.g. humming birds. Flowers are usually adapted to be pollinated by wind or by insects.