KEY STAGE 3 REPRODUCTION Boardworks Ltd 2001 Reproduction

KEY STAGE 3 REPRODUCTION © Boardworks Ltd 2001

Reproduction What is reproduction? Reproduction is when organisms produce new living things. Plants and animals reproduce to make new individuals of the same species. What do you think might happen if organisms didn’t reproduce? © Boardworks Ltd 2001

Asexual vs Sexual Not all organisms reproduce like humans do. In fact there actually two types of reproduction: 1. Asexual 2. Sexual © Boardworks Ltd 2001

Asexual Reproduction In asexual reproduction there is only one parent. The new individual is genetically identical to its parent. Organisms can reproduce asexually in many different ways. e. g: • Some very small organisms can simply divide into two e. g. bacteria • Some organisms can reproduce by ‘budding’. A part of their body breaks off and grows into a new organism. e. g some flowering plants © Boardworks Ltd 2001

Sexual Reproduction Most animals reproduce sexually. In sexual reproduction there are two parents. The parents have sex organs which produce sex cells or gametes. The offspring of sexual reproduction are genetically quite different to their parents. © Boardworks Ltd 2001

Activity Asexual or sexual? On the next slide is the names of eight different organisms. Drag their name to the correct table depending on whether you think that they carry out asexual or sexual reproduction. Think carefully! © Boardworks Ltd 2001

Activity © Boardworks Ltd 2001

A Bit of Both? Some organisms can carry out both sexual and asexual reproduction For example: Strawberry plants can reproduce by producing a miniature plant on a long shoot called a stolon. They can also produce new plants by sexual reproduction using flowers and seeds. © Boardworks Ltd 2001

Human Reproduction Humans use sexual reproduction to produce their young. In order to do this the two parents have to have sex organs so that they can produce sex cells. In humans males and females have different reproductive systems and sex organs Go to the activity on the next page to see how much you know. © Boardworks Ltd 2001

Activity Male or female On the next slide is the names of eight different parts of the male and female human reproductive systems. Drag their name to the correct table depending on whether you think that they are part of the male system or part of the female system. Do you really know as much as you think you do! © Boardworks Ltd 2001

Activity © Boardworks Ltd 2001

The Male Reproductive System © Boardworks Ltd 2001

The Female Reproductive System © Boardworks Ltd 2001

Activity © Boardworks Ltd 2001

Sex cells - Sperm In males the sex cells are called sperm. Sperm are produced in sex organs called testes Nucleus containing chromosomes Tail Middle piece Cell membrane Head © Boardworks Ltd 2001

Sex cells - Eggs In females the sex cells are called eggs. Eggs are produced in sex organs called ovaries. Nucleus containing chromosomes jelly coat cytoplasm membrane An egg is so big that this is how big a sperm looks next to it. © Boardworks Ltd 2001

Activity Sperm or Egg? Both sperm and eggs have special features that makes it possible for them to carry out their jobs. Look at the statements on the next page and decide which one you think belongs to an egg and which one belongs to a sperm. Once you think you know push the buttons to see if you are right. © Boardworks Ltd 2001

Activity © Boardworks Ltd 2001

Ovulation, and Fertilisation In the female one of the ovaries produces an egg every 28 days. This is called ovulation. During sexual intercourse sperm is ejaculated into the vagina. If the sperm and egg meet the sperms nucleus will join with the eggs nucleus. This is called fertilisation. © Boardworks Ltd 2001

Fertilisation and Implantation © Boardworks Ltd 2001

Activity Word Check © Boardworks Ltd 2001

The Placenta How does the embryo get food and oxygen and get rid of waste? It forms a plate like structure called the placenta. The umbilical cord joins the foetus to the placenta. In the placenta food and oxygen diffuse from the mothers blood into the blood of the foetus. Carbon dioxide and waste products diffuse from the blood of the foetus to the mothers blood. © Boardworks Ltd 2001

The Placenta © Boardworks Ltd 2001

Activity Embryo Development © Boardworks Ltd 2001

Puberty Human children are born with a complete set of sex organs. However they do not become active until later in life. Between 10 and 18 the testes start to make sperm and the ovaries start to make eggs. This time of development in their life is called PUBERTY. As well as these changes other changes may also occur. © Boardworks Ltd 2001

Activity Puberty in Girls © Boardworks Ltd 2001

Activity Puberty in Boys © Boardworks Ltd 2001

Menstruation One change that happens to girls at puberty is that they start to undergo a monthly cycle called the menstrual cycle. This cycle is a process where the uterus lining builds up to receive a fertilised egg. If an egg is not fertilised then the lining of the uterus breaks down and is lost from the body. This is called menstruation or a period. © Boardworks Ltd 2001

The Menstrual Cycle © Boardworks Ltd 2001

Control of the menstrual cycle • A pituitary hormone called follicle stimulating hormone (FSH) stimulates follicle to develop. This causes the eggs to divide and grow. • The follicle secretes oestrogen. This causes the uterus to thicken. The oestrogen travel to the pituitary gland via blood to stop FSH production and produce luteinising hormone(LH) which stimulates ovulation and transforms follicles into a yellow body. • The yellow body makes progesterone which thickens the uterus lining for pregnancy. © Boardworks Ltd 2001

Fertility Drugs • Often the cause of infertility in women is that ovaries do not release eggs. This is due to the lack of FSH. • Treatment: Injections containing FSH • Treatment: Tablets that makes pituitary insensitive to oestrogen. Why? • What if the man does not produce enough sperm? • AI: artificial insemination © Boardworks Ltd 2001