Decay

Question 1

Which organisms are detrivores?

Answer 1

• Earthworms
• Maggots
• Woodlice

Question 2

Why are they called detrivores?

Answer 2

They feed on dead and decaying material (detritus).

Question 3

What do detrivores do?

Answer 3

Detrivores increase the rate of decay by breaking up the detritus and therefore increasing the surface area for further microbial breakdown.

Question 4

What increases rate of decay.

Answer 4

• Increasing:
  
  • temperature,
  • amount of oxygen
  • water.

Question 5

What happens when temperature is increased?

Answer 5

Increasing the temperature to an optimun of 37 °C for bacteria or 25 °C for fungi will increase their rate of respiration. Higher temperatures will denature enzymes.

Question 6

What happens when the amount of oxygen is increased?

Answer 6

Bacteria will use aerobic respiration to grow and reproduce faster.

Question 7

What happens when the amount of water is increased?

Answer 7

Increasing the amount of water will allow for more material to be digested and absorbed more efficiently and increase growth and reproduction of bacteria and fungi.

Question 8

What is a saprophyte?

Answer 8

A saprophyte, for exampla a fungus, is an organism that feeds on dead and decaying material.

Question 9

What is meant by extracellular digestion?

Answer 9

Fungi produce enzymes to digest food outside their cells and then reabsorb the simple soluble substances. This type of digestion is called extracellular digestion.

Question 10

How is food preserved?

Answer 10

• Canning Food
• Cooling food
• Freezing food
• Drying food
• Adding salt or sugar to food
• Adding vinegar to food

Question 11

How does canning food reduce the rate of decay?

Answer 11

In canning, foods are heated to kill bacteria and then sealed in a vacuum to prevent entry of oxygen and bacteria.

Question 12

How does cooling food reduce the rate of decay?

Answer 12

Cooling foods will slow down bacterial and fungal growth and reproduction.

Question 13

How does freezing food reduce the rate of decay?

Answer 13

Freezing foods will kill some bacteria and fungi and slow down their growth and reproduction.

Question 14

How does drying food reduce the rate of decay?

Answer 14

Drying food removes water so bacteria cannot feed and grow

Question 15

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

Answer 15

Adding salt or sugar will kill some bacteria and fungi, as the high osmotic concentration will remove water from them

Question 16

How does adding vinegar to food reduce the rate of decay?

Answer 16

Adding vinegar will produce very acid conditions killing most bacteria and fungi.