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biology 0610printed 211 · PDF 211
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printed 211 · PDF 211
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ovule.
● The pollen nucleus travels all the way through the tube into the ovule. It fuses
with the ovule nucleus. Fertilisation has now taken place.
Seeds
● After fertilisation many parts of the flower are useless now. They wither and
fall off.
● In the ovary the ovule starts to grow. Each ovule now contains a zygote.
● The zygote divides by mitosis to form an embryo plant. The ovule is now a
seed.
● The seed contains very little water. Without water almost no metabolic
reactions take place inside the seed and it is said to be in a dormant state.
This helps it survive harsh conditions.
● For germination to occur the seed must have water, oxygen and a warm
temperature.
DIfferences in asexual and sexual reproduction
● Sexual reproduction produces offspring which are genetically different from
each other but asexual reproduction produces offspring which are genetically
same.
● Sexual reproduction leads to variation but asexual reproduction does not.
● Less variation in terms of asexual reproduction is useful if a plant is well
adapted to certain conditions and its offspring having its same characteristics
would be useful.
● Sexual reproduction is useful in an area where there is a lot of crowding and
competition. In this case asexual reproduction would make new organisms in
the same area increasing competition and making things even more crowded.