Pollination and Fertilisation + Seed Development

Question 1

what happens during seed development?

Answer 1

• specialised sex cells called gametes are produced
• there are usually two types - a mobile male gamete (sperm and pollen) and a stationary female gamete (ovum)
• the gametes must fuse (fertilisation), forming a single cell called a zygote
• the zygote will divide many times by mitosis to form all the cells of the new organism

Question 2

what happens during pollination?

Answer 2

1. in plants pollen grains are deposited onto the stigma
2. the pollen grain normally grows a pollen tube which grows down through the style
3. enzymes are secreted at the tip of the tube which digest the tissues of the style
4. when the tube reaches an ovule the male gamete travels through the tube entering the ovule through a small hole called the micropyle
5. it then fuses with the female gamete (ovum) in the process of fertilisation
6. the fertilises ovum divides by mitosis to form the embryo
7. the ovule develops into the seed
8. the ovary develops into the fruit

Question 3

what happens once fertilisation occurs?

Answer 3

the fertilised ovule becomes a seed the ovary becomes a fruit, whose job it is to disperse the seeds

Question 4

what is the process of fruit formation?

Answer 4

1. the zygote develops into an embryonic plant with a small root (radicle) and shoot (plumule)
2. the other contents of the ovule develop into cotyledons which will be a food store for the young plant when it germinates
   - the ovule wall becomes the seed coat, or testa (the hard coating of the seed)
3. the ovary wall becomes the fruit coat