Reproduction in flowering plants

list the 3 methods of asexual reproduction in plants

list the 3 methods of asexual reproduction in plants

1. bulbs

2. runners

3. tubers

asexual reproduction - bulbs

Underground food storage organs (with fleshy leaves that store food) grow and develop into new plants.

eg onions and garlic.

asexual reproduction - natural method - runners

• horizontal stem that grows along surface of ground.

• small roots grow into the soil and take over the main function of the main root of the plant.

• roots absorb water and minerals

• new plant is established

asexual reproduction - artificial method - plant cuttings

• involves the removal of part of a mature plant.

• a piece of stem/leaf is placed in soil.

• as it grows, it takes over functions of a root and becomes independent.

sexual reproduction in plants

• male and female gametes fuse and produce offspring which is genetically different to either parent.

asexual reproduction in plants

• new plants are genetically identical to parent plant.

• cells divide by mitosis to generate new cells in new plant.

• clone

stem

supports stem in a suitable position for pollination

sepals

enclose the flower when in bud. often green.

petals

• brightly colored to attracts insects (pollination)

• provide ‘landing platform’ for insects.

stamen

made up of anther and filament

anther

• contains developing pollen grains (male gamete)

• opens when pollen is mature.

• (pollen contains make cells)

filament

holds anther in correct position for pollen to be rubbed onto visiting insects.

carpel

• made of the stigma, style and ovary.

• contains nectar (sugary liquid that attracts bees.)

stigma

• receives pollen during pollination

• often sticky

style

• holds stigma in place.

• pollen tube joins style to ovary.

ovary

• contains the ovules, which encloses female gamete.

• may become part of fruit following fertilization

ovule

• contains the ovum (female egg cell)

• after fertilization with the male cell (pollen) an ovule develops into a seed.

structure of a wind-pollinated flower

• petals - are small or absent.

• no nectar or scent

• stamen - long filaments so anthers hang outside flower when ripe.

• pollen - large with smooth surface area to float through air. produced in large quantities.

• stigma - hangs outside the flower for increased chance of catching pollen in the air. often feathery.

structure of an insect pollinated flower

• petals - large and brightly coloured

• nectar and scent to attract bees

• stamens - enclosed in flower

• pollen - small. sticky so can stick to insects and stigma.

• stigma - enclosed in flower so insect brushes past it when entering flower.

pollination

• pollen transferred from stamen to stigma of another plant of the same species.

• pollen transported by insect/wind.

self-pollination

pollen lands on stigma of the same flower.

cross-pollination

pollen transferred to the stigma of another plant, of the same species.

fertilization

1. pollen grain lands on stigma of flower.

2. pollen tube grows down from style towards ovary.

3. pollen tube enters ovary through small gap (micropyle) and reaches ovule.

4. male nucleus in pollen fuses with female egg cell in ovule.

5. fertilization occurs and a zygote if formed.

adaptations of the pollen tube for fertilization

digestive enzymes produced by tip of pollen tube enable it to grow through tissues in the style to reach the ovary.

how are seeds and fruit created after pollination?

1. zygote divides into cells that form embryo.

2. embryo grows into seedling.

3. ovule becomes seed coat and parts of flower surrounding ovule become fruit.

conditions needed for seed germination

• water

• oxygen

• suitable warm temperature

• some need light

explain how germinating seeds utilise food reserves until the seedling can carry out photosynthesis

1. surrounding the embryo are cotyledons.

2. these contain food reserves that supply the seedling with food materials when the seeds start to germinate.

3. embryo gets glucose (for respiration) from its own food store. This transfers the energy it needs to grow.

4. once plant has grown enough to produce green leaves, it begins photosynthesizing.

explain a practical to investigate the conditions needed for seed germination

1. 4 test tubes with cotton wool and 10 cress seeds sprinkled on top.

2. tube A - dry cotton wool, room temp. in the light

3. tube B - moist cotton wool, room temp. in the light

4. tube C - moist cotton wool, room temp. in the dark

5. tube D - moist cotton wool, in the fridge, in the dark

6. leave test tubes for 3-5

7. observe which tubes have germinated