Hormones regulatethe functions of many organs. Complete the following sentences.
a. Hormones control the monthly release of an egg from the woman's ovaries.
b. Hormones also control the thickness of the lining of her uterus.
c. Hormones given to women to stimulate the release of eggs are called fertility drugs.
Many diseases are caused by viruses. Children are given vaccines to protect them against viral disease. Complete the following sentences.
It is difficult to kill viruses inside the body because viruses reproduce inside our cells and remain inactive until they break out. Killing the virus would kill the cells.
The vaccine stimulates the white blood cells to produce antibodies.
Adult/fusion cell cloning is an example of asexual reproduction. Explain why.
The genetic material only comes from the nucleus of one parent's cell; the nucleus from the other cell used is removed before fusion.
Darwin's theory of evolution via natural selection was only gradually accepted. Give two reasons why.
(Any two of the following)
1. He disputed the ideas of the church that God created the earth.
2. There was insufficient evidence at the time.
3. No one had any knowledge of genes, DNA or inheritance at the time.
a. Explain how a population of antibiotic-resistant bacteria might develop from non-resistant bacteria.
The antibiotics kill the majority of the bacteria, but a small percentage of the population mutate and become resistant. These survive, causing variation in the strains of bacteria. The resistant gene is passed on to the offspring, causing the size of resistant population to increase.
b. Suggest two reasons why it is an advantage to keep farm animals disease free.
1. To prevent diseases spreading to other animals and humans.
2. So that energy can be used to produce good products e.g. milk, instead of being used to repare the body.