1. Lesson Starter What are the male and female sex cells in animals?
Where is the male sex cell produced?
Where is the female sex cell produced?
What is the job of the penis?
Where does the baby grow?
What is a zygote?

2. Sexual & Asexual reproduction
Lesson 5

3. Lesson 5- learning intention
Discuss internal and external fertilisation and chances of survival

4. Animal Fertilisation
Fertilisation is when the nucleus of the egg and nucleus of the sperm FUSE together- a zygote is formed
The zygote contains a full set of chromosomes- half from the sperm and half from the egg

5. Haploid and Diploid
All of the cells in our body (except our sex cells) are DIPLOID
They all have TWO SETS of chromosomes
Called SOMATIC cells
Sex cells (egg and sperm) only have one set of chromosomes
They are haploid

6. Fertilisation There are two types of fertilisation-
Internal fertilisation
External fertilisation

7. External Fertilisation
Most animals that live in water carry out external fertilisation
The sperm and egg cells are released into the environment
Large number of gametes released to ensure fertilisation happens
External fertilisation uses a lot of energy

8. Increasing chances of survival
Animals that use external fertilisation (e.g. trout and frogs) produce far more eggs than animals that use internal fertilisation (e.g. birds and mammals).
WHY?

9. Increasing chances of survival
Animals that use external fertilisation (e.g. trout and frogs) produce far more eggs than animals that use internal fertilisation (e.g. birds and mammals).
there is a greater risk of eggs being eaten by predators or not being fertilised as the sperm drift away

10. Development of young
Unfertilised gametes make up part of sea plankton (and become part of aquatic food chains)
In fish such as trout, once the fertilised eggs develop, they hatch. The fish must use their yolk sac as a food source until they are able to swim and feed on their own.

11. Internal Fertilisation
Carried out by the majority of land animals
Internal fertilisation is complicated because:
- Mates need to find each other (and compete with rivals)
- Mating needs to be co-ordinated with seasonal timing of gamete production
-Specialised reproductive organs are needed
-Parental care is needed after the young are born

12. Increasing chances of survival
During fertilisation the sperm cell is placed inside the body of the female during sexual intercourse
Internal fertilisation has an increased chance of fertilisation as the gametes are closer together
Fewer gametes are needed for fertilisation so less energy is used

13. Development of young
Mammals use internal development which means the embryo develops inside the mother’s body. This keeps the embryo warm, fed and protected by one or both parents.
In birds, their eggs must be incubated (kept warm) before they can hatch. In the nest once the eggs have hatched, parents must take care of their young since they cannot fly or feed themselves at first

14. Fertilisation: copy
Fertilisation is when the nucleus of the egg and sperm cell fuse together to form a zygote
There are two types of fertilisation: Internal which happens inside the body as a result of sexual intercourse (birds and mammals) and external which is when the egg is fertilised outside of the body (fish)

15. Task Write a paragraph comparing internal and external fertilisation
Include
- The type of animal that uses it
- The number of gametes released
- Why that number of gametes are released
- The amount of energy used