Bacteria and making yoghurt
Answers are for parents and teachers.
1
Find three foods in your kitchen that are made with the help of bacteria (for example yoghurt, suzma, pickled cucumbers) and write what the bacteria do in each.
Free answer; for example: in yoghurt and suzma lactic acid bacteria turn milk sugar into lactic acid; in pickles fermenting bacteria make lactic acid that keeps the vegetables from rotting.
2
One bacterium divides every 30 minutes. How many bacteria are there after 2 hours (if food is enough)?
16
3
Write the steps of proper handwashing and show them to your family.
Wet hands, apply soap, rub palms, backs, between fingers and nails for 20 seconds, rinse well and dry.
4
Write the method of making yoghurt in six steps and give the reason for each.
Boil the milk (adult); cool to warm (so bacteria survive); add starter; wrap and keep warm; wait for it to set; refrigerate.
5
Why does soil become richer in nitrogen in a field where legumes (such as alfalfa) are grown?
Nodule bacteria on their roots take nitrogen from the air and pass it to the plant and soil.