5.1) Copy and complete each sentence, using words from the list. You may use each word once, more than once or not at all.
egg             ovary             embryo             oviduct             fertilisation             uterus             gametes
a: Sperm cells and egg cells are .........
b: The joining together of the nucleus of a sperm cell and the nucleus of an egg cell is called .............
c: A zygote is formed in the ............
d: A zygote divides repeatedly to form an ..................

5.2) The graph shows the mean mass of girls at different ages.

a: What is the mean mass of girls when they are 2 years old?
b: By how much does the mean mass increase between 2 years and 10 years old?
c: Between which ages does growth take place most rapidly?
d: Does the graph show that most girls have stopped growing by the age of 20?

5.3) In some countries, pregnant women are able to have an ultrasound scan, to check that their baby is growing properly.
The picture shows an ultrasound scan of a foctus in the uterus, 12 weeks after fertilisation.

a: The foctus is floating in a fluid, which looks black in the picture.
What is the name of this fluid?
b: What is the function of the fluid?
c: Name the organ that connects the foetus to its mother's uterus, and through which it obtains its food and oxygen.
d: When it is fully developed, the baby will be born. Describe how a baby is born.

5.4) An experiment was carried out to find out how nicotine affects the production of sperm cells in rats.
40 male rats were divided into three groups. One group was given no nicotinc, another group was given a low dose of nicotinc cach day and the third group was given a high daily dose of nicotine. This continued for 30 days.
The researchers then studied the rats' sperm cells, and counted how many sperm cells were not normal. The table shows their results.

a: Draw a bar chart on graph paper, to show these results.
b: Write a conclusion that the researchers can make from their results.
c: Suggest why the researchers gave no nicotine to one group of rats.
d: Suggest two variables that the researchers should have kept the same in their experiment.