Sexual reproduction in animals Flashcards
What types of animals use external fertilisation?
Animals that breed in the water, like amphibians, fish and coral
What happens during external fertilisation?
Gametes are released into the water, and fertilisation is left to chance
What features help a young fish survive?
Some eggs have a tough, protective covering
The developing embryo obtains food from yolk in the egg
Is there usually paternal care in external fertilisation?
No, as soon as the young fish emerges from the egg, it’s able to look after itself
How do you guarantee survival in external fertilisation?
Producing many young so a few survive
How can we increase the chances of external fertilisation?
2 parents are close together when gametes produced (fish&frogs)
Gametes are placed in a nest (sticklebacks)
Gametes released at the same time (coral mass spawning)
What do both sperm and eggs need to survive?
An aquatic environment
Where is sperm produced?
The testes
Why is sperm released inside the female reproductive system?
Both eggs and sperm need an aquatic environment to survive
Where are eggs made?
The ovary in the female reproductive system
What happens after implantation?
Embryo develops inside the uterus where it’s protected and receives food and oxygen until birth
What does the fertilised egg do to form an embryo?
The egg divides repeatedly
How are the young protected and nourished when inside?
(Before birth)
Developing foetus protected by amniotic fluid (prevents knocks) and the placenta (barrier to harmful substances). Placenta also supplies food and oxygen
How are the young protected and nourished when inside?
(After birth)
Many animals have extended period of parental care where young are looked after from birth.
Mammals produce milk to feed them. Fewer young produced as most are likely to survive
