Reproduction in plants

For IGCSE O-Level Biology students
Chapter 13

1. Reproduction in plants

2. Sexual & asexual reproduction Sexual reproduction: Two parents Fusion of a female & male cells (gametes) Parent & offspring are not identical Slower Variation is present in the same species Asexual reproduction: One parent only No gametes are produced Parent and offspring are identical Faster No variation

3. Examples of asexual reproduction. Budding in yeast     Nucleus replicates Nucleus migrates to one end Part of the cell grows into a bud The bud separates creating a new cell

4. Examples of asexual reproduction. Vegetative reproduction in potato plants

5. Examples of asexual reproduction. Runners in strawberry

6. Sexual reproduction in plants To reproduce sexually plants have male and female reproductive organs in their flowers. The male part is called the stamen The female part is called the carpel

7. Pollination It is the transfer of pollen grains from the anthers to the stigma Pollinating agents Insects Wind

8. Differences between insect & wind pollinated flowers Insect pollinated Wind pollinated Have large colored petals with guide lines Have a scent Have a nectary on which insects feed Have a sticky stigma for pollen grains to stick on it The female and male organs are enclosed in the flower Pollen grains are larger with spikes to hold on insect body Have small green petals, no guide lines Have no scent Have no nectary Have a feathery stigma to catch the pollen in the air The female and male organs are hanging outside the flower Pollen grains are smaller & light weight to be carried by wind

9. Pollen grains as seen under the microscope Can you tell which belongs to insect pollinated flowers / wind pollinated flowers?

10. fertilisation It is the joining of male and female cells to produce a zygote. Ovary Fruit Ovary wall Fruit cover Ovule Seed

11. Seed structure D

12. Seed-fruit dispersal If a seed lands next to the parent plant and germinates it will compete with the parent plant for nutrients in the soil. Most plants developed methods to scatter/disperse their seeds to ensure they land further away from the original plant. There are 2 main methods of seed dispersal: Wind dispersal Animal dispersal

13. Wind dispersal Parachute e.g. dandelion Winged fruits e.g. Acer

14. Animal dispersal Hooked fruits e.g. Burdock and others

15. Animal dispersal Other fruits are large coloured and fleshy/juicy to attract animals to eat them, swallowing the seeds at the same time. The seeds have hard indigestible testa that pass out with faeces in a new area away from original plant. Example of such fruits: apple, acorn, strawberries…etc.

16. Seed germination Once a seed falls onto a suitable surface it starts to grow. Conditions required for seed germination: Suitable temperature Oxygen Water