2. Sexual Reproduction

Advantadges

individuals posess favourable traits leading to adapting to selective pressures, thereby enhancing species survival

Disadvantadges

• more energy and time to produce gametes

• slower population growth compared to asexual reproduction

Plants - Male part (Stamen) is made up of..

• Anther - produces pollen grains

• Filament - stalk that supports the anther

Plants - Female part (Carpel) is made up of…

• Stigma - sticky surface that traps pollen

• style - connects stigma to the ovary

• ovary - contains ovules aka female gametes

Pollination

the transfer of pollen from the anther to the stigma

seed formation

developmemt of the fertilised seed into an ovule and the ovary into a fruit

seed disperal

movement of seeds away from the parent plant to reduce competition and increase survival

germination

growth of the embryo into a new plant when conditions are favourable.

Fertilisation in plants

the pollen nucleus (male gamete) fuses with the ovum (female gamete) inside the ovule (ovary)

Steps in fertilisation

1. pollen lands on the stigma

2. a pollen tube grows down the style to the ovary

3. the nucleus from the pollen moves downs this tube to feretilise the female gamete nucleus inside the ovule, forming a zygote

4. The fertilised egg develops into an embryo found inside the ovule which becomes the seed

5. The ovary becomes the fruit after flowering has taken place

self pollination

the transfer of pollen within the same flower or plant. This ensures reproduction when pollinators are scarce

cross pollination

The transfer of pollen between different plants of thee same species, which increases genetic variation thus better survival

seed dispersal allows offspring to spread away from the parent plant, why is this important?

reducing competiion of resources like habitat, nutrients and increasing chances of survival.

wind dispersal

seeds are lightweight or have wing-like structures

water dispersal

seeds float and are carried by water currentss

animal dispersal

seeds may be carried by animals through ingestion of fleshy fruits or attachment via hooks and burrs,

Info on germination

• seeds remain indormant until enironmental conditions are favourable

• germination requires adequate water, oxygen and warmth.

• the radicle (root) emerges first, followed by the plumule (shoot), which develops into a seedling and grows into a mature plant.

Internal fertilisation

the fusion of male and female gametes inside the body

advantadges of internal fertlisation

• suitabke for organisms in terestrial environments (insects, kangaroos)

• higher success rate as gametea re deposited into a controlled environment

• recieving parental care, improving chance of survival

disadvantages of internal fertilisation

• requires time and energy involving higher parental care and long gestation periods

• reduces genetic diversity

• fewer offspring produces

external fertilisation

the fusion of male and female gametes outside the body

advantagdes of external fertilisation

• good for organisms in aquatic environments as water prevents gametes from drying out

• Large number of gametes produced quickly

• less energy as there is no need to find mates

• greater genetic diversity, female eggs can be fertilised by more than one males sperm

disadvantadge of external fertilisation

• offspring is prone to being exposed to environmentfal threats, and predators, reducing surivial rate

• gametes can get wasted if destroyed or eaten beforoe fertilisation even occurs