Plant Reproductive System P5

Question 1

Male Reproductive Parts

Answer 1

1. Anther contains pollen sac with pollen grains (male reproductive cells)
2. Filament supports the anther
3. Both together are called the stamen

Question 2

Female Reproductive Parts

Answer 2

1. Stigma receives pollen grains
2. Style connects the stigma to the ovary
3. Ovary protects the ovule and becomes a fruit after fertilisation
4. Ovule contains the egg cell (female reproductive cell) and develops into a seed after fertilisation

Question 3

Sexual Reproduction Steps

Answer 3

Pollination —> Fertilisation —> Seed Dispersal —> Germination

Question 4

Pollination by Animals

Answer 4

1. Flowers have large and brightly-coloured petals
2. Flowers may be scented and produce nectar
3. Anther and Stigma within the flower (filament and style short)
4. Stigma is sticky to catch pollen grains

• Pollen grains usually cling or stick to the animal’s legs or back and they’re transferred when animal touches the stigma of another flower

Question 5

Pollination by Wind

Answer 5

1. Petals are small and dull
2. Unscented and do not produce nectar
3. Long filament and style for anther and stigma to hang out of the flower
4. Stigma is large and feathery to increase surface area to catch pollen grains

• Pollen grains are small and light, allowing them to be carried away by the wind easily from the anther

Question 6

Fertilisation

Answer 6

Male sex cell within pollen grain fuses with egg cell within the ovule to form a fertilised egg. This turns into a seed when the flower matures into a fruit

Question 7

Seed Dispersal Function

Answer 7

1. To prevent overcrowding
   - Reduces competition between young and parent plants for sunlight, water, nutrients and space (not air)
2. Allow young plants to grow in more favourable environments

Question 8

Wind Dispersal

Answer 8

1. Seeds/Fruits are usually dry, small and light
2. Some may have wing-like (angsana, shorea) or feathery (dandelion) structures that help them remain airborne and travel over longer distances.
3. Young plants grow in the direction of the prevailing wind

Question 9

Water Dispersal

Answer 9

1. Fruits have fibrous husks that trap air
2. and waterproof coverings
3. so they remain buoyant in water
4. Usually found along coastline or down streams of riverbanks

Question 10

Splitting/Explosive Action

Answer 10

1. Fruits split open explosively when their seed pods have dried up
2. Usually growing in clusters near the parent plant
3. Good because plants do not need to rely on any external agents
4. Bad because higher tendency for overcrowding

Question 11

Animal Dispersal

Answer 11

1. Fruits are fleshy, sweet and juicy and are eaten by animals.
2. Animals then throw away large seeds or swallow and excrete small indigestible seeds
   OR
3. Fruits/Seeds have hooks, sticky hair or bristles
4. that clings onto clothing of humans or outer covering of animals and fall off away from parent plant
5. Animal dispersal pattern is random.