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Fertilisation.

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Presentation on theme: "Fertilisation."— Presentation transcript:

1 Fertilisation

2 The male reproductive system

3 The female reproductive system

4 Male or female?

5 Reproductive system

6 Label the parts….

7 Label the parts

8 From a cell to DNA

9 Sex cells – sperm In males, the sex cells are called sperm.
Sperm are produced in sex organs called testes.

10 Sex cells – egg In females, the sex cells are called eggs.
Eggs are produced in sex organs called ovaries. nucleus containing chromosomes cytoplasm membrane jelly coat An egg is so big that this is how small a sperm looks next to it.

11 Fertilization and cell division – animation

12 Identical twins – animation

13 Non-identical twins – animation

14 Sexual Reproduction Although all cells carry the genetic code, special cells are produced for sexual reproduction – they are called gametes. In animals, these are the eggs and sperm. In plants, they are the eggs and pollen. Gametes are different from all other cells because they only carry one copy of each chromosome. For example, human gametes (sperms and eggs) have only 23 chromosomes, not 46 like all other body cells.

15 The process of a male and female gamete combining is called fertilisation.
The fertilised egg is called a zygote and is the very first cell of a new individual. A zygote will have the normal number of chromosomes – one half from the male gamete, another half from the female gamete. This whole process is called sexual reproduction.

16 The menstrual cycle

17 The menstrual cycle The menstrual cycle is when the body prepares the uterus lining so that it is able to receive a fertilized egg.

18 When is the fertile period?
This is the time in the cycle when the woman could get pregnant after having sex. When is the fertile period? Between days 11 and days 16 of the menstrual cycle

19 Label the parts…

20 Male sex cells In males, the sex cells are called sperm. They are made in the testes

21 An egg is so big that this is how small a sperm looks next to it.
Female sex cells In females, the sex cells are called eggs. They are made in the ovary. nucleus containing chromosomes An egg is so big that this is how small a sperm looks next to it.

22 Sperm or egg?

23 Ovulation and fertilization
In the female, one of the ovaries releases an egg every 28 days. This is called ovulation. During sexual intercourse millions of sperm are ejaculated into the vagina. If a sperm meets the egg a zygote is formed. This called fertilization.

24 Fertilization and implantation

25 What happens after fertilisation?
Once the zygote is made the cells divide many times It is now called an embryo and it will sink into the lining of the uterus, this is called implantation.

26 The placenta How does an embryo get food and
oxygen and how does it get rid of waste? A placenta is formed which allows it to exchange material with the mother The umbilical cord joins the embryo to the placenta.

27 The placenta

28 What happens in the placenta?
In the placenta, food and diffuse from the mother’s blood into the blood of the fetus. Carbon dioxide and waste products diffuse from the blood of the fetus to the mother’s blood.

29 From embryo to fetus After the first eight weeks of pregnancy,
a human embryo is then called a fetus. The fetus continues to develop and grow inside its mothers’ uterus for a total of 40 weeks. What happens next?

30 From embryo to fetus – animation

31 Birth animation

32 What is puberty? Think about…
Puberty is the stage between the ages of 10 – 18 when the sex organs of humans become active Think about… What happens to i) boys and ii) girls during puberty?

33 Puberty in girls

34 Puberty in boys

35 Modern contraceptives

36 Boardworks KS3 Science 2008 Human Reproduction
Multiple-choice quiz


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