iGCSE Biology 3 - reproduction - flowering plants

Define sexual reproduction

The fusion of male and female gametes to form a zygote

Define asexual reproduction

The new individual from a single parent without fusing or gametes

Sexual reproduction - offspring genetic makeup

Genetic variation

Asexual reproduction - offspring genetic make up

Genetically identical/clones

Sexual reproduction - type of division

Meiosis of gametes and mitosis of embryo

Asexual reproduction - type of division

Mitosis and Binary Fission

Sexual reproduction - DNA

Mix of both parents

Asexual reproduction - DNA

Identical to parent

Sexual reproduction - gametes involved (list for animals and plants separately)

• sperm and egg (animal)

• pollen and ovule (plant)

Asexual reproduction - gametes involved?

None haha

Speed of sexual vs asexual reproduction

Sexual = slower, Asexual = faster

Examples of species that undergo sexual reproduction

Most mammals, flowering plants, fish and fungi

Examples of species that undergo asexual reproduction

Bacteria, strawberry runners, potato tubers

Sexual reproduction - 3 advantages

• genetic variation in offspring

• in case of disease or other environmental change, offspring more likely to survive

• drives natural selection

Asexual reproduction - advantages

• faster, no mate required

• useful in isolated environment with low population

• clones are good for organisms that are well adapted to environment

What does a flower’s carpel consist of?

Stigma + Style + Ovary

What does a flower’s stamen contain?

Filament + Anther

Pollination - definition

Transfer of pollen from anther to stigma of the same species

Name 2 types of pollination

• Insect

• Wind

Insect pollination adaptations (4)

• large and brightly coloured petals

• sticky stigma inside flower for pollen to stick onto insect

• scent and nectary

• enclosed anther increases chance of brushing against insect

Wind pollination adaptations (4)

• long filament with exposed anthers

• small and light pollen grains

• large quantities of pollen increases chance of pollination

• large feathery stigma to trap drifting pollen

7-step process of Fertilisation

1. Pollen lands on stigma

2. Pollen grows on pollen tube

3. Pollen tube grows down style

4. Male nucleus travels down pollen tube

5. Pollen tube enters ovule via micropyle

6. Male nucleus fuses with female nucleus

7. A zygote is formed

What does the zygote eventually become?

Embryo

What does the ovule eventually become?

Seed

What does the ovary eventually become?

Fruit

What does the ovary eventually become?

Ovary wall

Germination occurs when the seed begins to — and the — + — appear.

• grow

• radicle

• plumule

Plumule

Develops into leaves and stem

Radicle

Develops into roots

3 conditions needed for germination, each explained

• warmth - enzymes and optimum temp

• water - softens the testa, causing seed to swell, activates enzymes to allow reactions to occur

• oxygen - for aerobic respiration, releases energy for growth

Self vs Cross pollination: pollen goes to…

Stigma on same plant vs Stigma of different plant

Self vs Cross pollination: need of pollinator…

No, reliable on its own vs yes, wind/animal needed

Self vs Cross pollination: main advantage

Guaranteed reproduction w/ self vs offspring can adapt and survive better

Wind pollination adap