fertilisation and germination

• what is fertilisation in plants?

  • pollen grain lands on stigma of flower
  • pollen tube grows out of pollen grain - down through style - to ovary - into ovule
  • nucleus from male gamete moves down tube to join with female gamete in ovule
  • two nuclei fuse together to form a zygote which undergoes mitosis and becomes an embryo
  • fertilised female gamete forms seed - ovary develops into a fruit around the seed
• what is germination's process?

  • seed often lie dormant until conditions around it are right for germination
  • water - active enzymes to break down food reserves in seed
  • oxygen - for respiration - transfers the energy from food for growth
  • suitable temperature - for enzymes inside the seed to work - depends on type of seed
• how do germinating seeds get energy from food stores?

  • developed seed contains embryo and food reserves store - wrapped in hard seed coat
  • seeds starts to germinate - gets glucose for respiration from own food store - transfers energy needs to grow
  • once plant has grown enough to produce green leaves - can get own food for energy from photosynthesis