B4g - Decay

Question 1

What 3 things does the rate of decay depend on?

Answer 1

temperature
amount of water
amount of oxygen

Question 2

How does a warm temperature affect the rate of decay?

Answer 2

it makes things decay faster because it speeds up respiration in microorganisms

Question 3

How does a moist atmosphere affect the rate of decay?

Answer 3

things decay faster because microorganisms need water

Question 4

How does an oxygen rich atmosphere affect the rate of decay?

Answer 4

decay is faster as microorganisms can respire aerobically providing more energy

Question 5

What are the optimum levels for microorganisms?

Answer 5

warm
moist
plenty of oxygen

Question 6

What happens to these microorganisms when these factors are at optimum levels?

Answer 6

microorganisms grow and reproduce more quickly meaning there will be more of them to decay other living things

Question 7

What are detritivores?

Answer 7

organisms that feed on dead and decaying material

Question 8

what is detritus?

Answer 8

dead and decaying material

Question 9

What are some examples of detritivores?

Answer 9

earthworms
maggots
woodlice

Question 10

How do detritivores increase the rate of decay?

Answer 10

they break up the decaying material into smaller bits giving a bigger surface area for smaller decomposers to work on and speeds up the decay

Question 11

What is a saprophyte?

Answer 11

an organism that feeds on decaying material through extracellular digestion

Question 12

What is extracellular digestion?

Answer 12

secreting digestive enzymes on the material outside of their cells. The enzymes break down the material into smaller bits, which can then be absorbed by the saprophyte.

Question 13

Give an example of a saprophyte

Answer 13

fungi

Question 14

What are microorganisms used for?

Answer 14

to break down human waste (sewage)

to break down plant waste (compost)

Question 15

What are the main food preservation techniques?

Answer 15

canning
cooling
freezing
drying
adding salt/sugar
adding vinegar

Question 16

How does canning reduce the rate of decay?

Answer 16

by putting food in an airtight can, decomposers are kept out

Question 17

How does cooling reduce the rate of decay?

Answer 17

putting food in the fridge slows down decay because it slows the decomposers reproduction rate

Question 18

How does freezing reduce the rate of decay?

Answer 18

food lasts longer in the freezer than in the fridge because decomposers cant reproduce at all at such low temperatures

Question 19

How does drying reduce the rate of decay?

Answer 19

dried food lasts longer because decomposers need water to carry out cell reactions

Question 20

How does adding salt/sugar reduce the rate of decay?

Answer 20

if there’s a high concentration of salt/sugar around the decomposers they’ll lose water by osmosis which damages them and means they can’t work properly

Question 21

How does adding vinegar reduce the rate of decay?

Answer 21

vinegar is acidic and acid kills the decomposers