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8 Cards in this Set
- Front
- Back
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What is external fertilisation? |
Occurs outside the female. The male releases sperm cells onto the egg cells as the female lays them |
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Why does external fertilisation need water? |
Needs water for moisture for egg and sperm |
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In what type of animals would external fertilisation occur? |
Fish and most water dwelling animals eg amphibians |
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How are the make and female sex cells released near each other? |
There are usually courtship rituals which make sure the male and female sex cells are released near each other |
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Why are large numbers of eggs and sperm needed? |
The chances of fertilisation are very low, so huge numbers of eggs and sperm are needed to ensure enough offspring are produced |
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What is internal fertilisation? |
Occurs inside the female. Occurs in most land dwelling organisms such as mammals. Need fluid as sperm needs fluid in order to be able to swim to the egg. (fluid comes from semen, ejaculated along with the sperm from the male) |
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Why are there so few sex cells produced in internal fertilisation? |
As the liklihood of successful fertilisation is higher in internally fertilised organisms because the sex cells are so much closer together, producing a great many sex cells would cause problems |
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What are the 3 reproductive strategies? |
- Oviparity: animal lays eggs. Eg chicken, birds, amphibians. Altricocial birds: born blind, helpless, nest in tree. Precocial birds: born with feathers, ready to move and see, nest on ground - Viviparity: animal gives live birth. Eg mammal such as humans. (Amniotic sac) - Ovoviviparity: egg develops inside mother until right before it hatches. Eg rattlesnake, fish |
