Reproduction in plants

Vegetative propagation

1. The aerial shoots die in unfavourable conditions and the underground storage
organs remain dormant .

2. New aerial shoots grow from the buds of the storage organ under favourable
conditions using the food from the storage organ

3. Adventitious roots develop to absorb water and minerals and green leaves grow
then new plants are formed , the storage organ dries up as food is used up

4. New plants produce food by photosynthesis and some food is transported to

Sexual reproduction

A : ovule B : ovary C : style D : stigma E: carpel

F : anther G : stamen H : lament I: sepal J: petals /

Adaptations for insect pollination

1.Anther located inside the ower

2. The stigma is broad and sticky to pick up pollen

3. Large brightly coloured petals and nectar guides to

4. Pollen grains are sticky , spiked and rough to attach on insect bodies

Adaptations for wind pollination

1. Anthers located outside the ower to help release of pollen into the wind

2. Feathery stigma to catch pollen in the wind

3. Thin laments to allow anthers to move in the wind to aid release of pollen

4. Dry , smooth pollen grains

Self pollination vs cross pollination

Transfer of pollen from anther to stigma

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 Fertilisation

1. The pollen grain lands on the stigma of a ower and germinates with the help of
the sugary solution secreted by the stigma

2. A pollen tube develops from the pollen and grows down the style carrying the
male gamete by secreting enzymes to digest the tissues of style

3. The pollen tube grows through the micropyle and bursts to release the male
gamete

4. The male gamete fuses with the female gamete and forms a zygote

Before fertilisation. After fertilisation

Stamen+ petals + sepal Withered and falls o

Remains of style and stigma. Scar

Ovary wall. Fruit wall

Ovule Seed

Ovum. Embryo

Integument. Seed coat

Features for di erent types of seed dispersal

Animal : brightly coloured fruit and eshy fruit wall to attract animals to eat the fruit
+ have hooks to cling to the fur of the animal

Air : light and parachute like seed + by explosions to propel the seed away

Water : the fruit is buoyant

Advantage of vegetative propagation

1. No external agents are needed

2. Occurs at a relatively high rate

3. Desirable traits can be retained

Advantage of sexual reproduction

1. Produce genetic variation in o spring so the chances of survival of whole

2. Reduce overcrowding and competition with parents

3. Allow o spring to escape from pests and disease associated with parents

Disadvantage of vegetative propagation

1. There is no genetic variation in o spring so the chances of survival of whole

2. Overcrowding and intense competition of resources occurs

3. Disease from parent plants are transmitted easily to o spring

Disadvantage of sexual reproduction

1. External agents required

2. Occurs at relatively slow rate

3. Desirable traits are not retained

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