Research this Find out about the positive effects of bacteria in our digestive systems and answer these questions: 1. What do the good bacteria do for us? 2. What can stop the good bacteria from growing?
Fungi Fungi can occur as single cells (e.g. yeast), as long, fine threads (e.g. bread mould) or as larger structures (e.g. mushrooms). Fungi feed by absorbing food. They cannot make their own food. Fungi have both beneficial and harmful effects on humans. Fungi that benefit us include the fungus Penicillium which produces an antibiotic, yeast which helps make dough rise in baking, and many mushrooms are edible. However, some fungi cause diseases, e.g. athlete’s foot, some spoil food, e.g. bread mould, and some mushrooms are very poisonous.
Fig. 3 Athlete’s foot is caused by fungi. Extended Investigation
Design an experiment to find out what can be done to slow down the growth of mould on bread.
Viruses Viruses are extremely tiny and cannot be seen with a light microscope. They are usually made from a small amount of DNA surrounded by a protein coat. Viruses attack living cells and use the cells to make more copies of the virus which then infect other cells. Viruses cause many diseases, for example flu, common colds,
Ebola and HIV/AIDS. We can catch these illnesses in various ways. l
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Colds and flu are transmitted in liquid particles, e.g. by coughing and sneezing. Ebola is transmitted through touch. HIV is transmitted through exchange of body fluids, e.g. blood or semen.
