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gcse science B4 - G
specific for ocr gateway additonal science B.
| Question | Answer |
|---|---|
| what does detritus mean? | remains of dead and decaying plants and animals |
| what are detritivores? | animals which depend on detritus for their food |
| examples of detritivores? | earthworms, maggots, woodlice |
| what do detritivores do? | speed up decay as they break the detritus down into smaller pieces, which increases the surface area |
| why are detritivores important? | they recycle chemicals from dead plants and animals |
| what is another method of using decay? | for compost |
| what conditions speed up the composting process? | -warmth -moisture -good aeration (to allow oxygen in) |
| what happens inside a compost bin? | microorganisms respire, which give off heat and warms up the compost, which speeds up decay |
| what does decay depend on? | enzyme action - conditions that speed up enzyme action also speed up decay |
| what is the optimum temperature for bacteria? | 37 |
| what is the optimum temperature for fungi? | 25 |
| what are the two types of bacteria? | aerobic and anaerobic |
| why do aerobic bacteria break down dead detritus quickly? | because they produce oxygen, which speeds up decay |
| why do anaerobic bacteria break down dead detritus slowly? | because they produce acid conditions, which slows down decay |
| what is a saprophyte? | a fungus that feeds off dead and decaying materials |
| what happens to the saprophyte's digestive enzymes? | released on to the food and break it down into simple soluble substances so the digested food is absorbed easily |
| what are the 5 ways to preserve food? | canning, cooking, vinegar, drying, freezing, adding sugar or salt |
| how does cooking work? | kills bacteria. food poisoning is caused by food being undercooked |
| how does canning work? | killheats food before being canned to kill the bacteria. then sealed in a can to stop any bacteria getting ins bacteriA |
| how does vinegar work? | it's an acid. very few bacteria can grow in acid conditions. |
| examples of food preserved in vinegar? | pickled eggs, chutney |
| how does drying work? | bacteria and fungi can't grow without water |
| examples of food preserved by drying? | cereals |
| how does freezing work? | kills bacteria or slows their growth |
| how does adding sugar or salt work? | kills some bacteria and fungi and stops the growth of others |
Created by:
jirwin
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