Decomposition

Question 1

The rate of decay

Answer 1

is the speed at which dead matter is broken down by decomposers.

Question 2

How was the rate of decay estimated

Answer 2

by measuring changes in pH

Question 3

How can decomposition be effected by temperature

Answer 3

At colder temps decomposing organisms will be less active, thus the rate of decomposition remains low. This is why we keep food in a fridge. As the temperature increases, decomposers become more active and the rate increases. At extremely high temperatures decomposers will be killed and decomposition will stop

Question 4

How can water effect decomposition

Answer 4

Water
With little or no water there is less decomposition because decomposers cannot survive. As the volume of available water increases, the rate of decomposition also increases. Many decomposers secrete enzymes onto decaying matter and then absorb any dissolved molecules. Without water these reactions cannot occur.

Question 5

Oxygen effects decomposition how

Answer 5

Similar to water, decomposers need oxygen to survive and without it there is little or no decomposition. Oxygen is needed for many decomposers to respire, to enable them to grow and multiply. This is why we often seal food in bags or cling film before putting it in the fridge. As the volume of available oxygen increases, the rate of decomposition also increases. .

Question 6

Anaerobic decay occurs in what conditions

Answer 6

Occurs when bacteria and fungi break down dead matter without oxygen. This can happen naturally in some soils, particularly water logged soils and in lakes and marshes. When people over water their houseplants and flood the roots, anaerobic decay can occur, which can kill them

Question 7

anaerobic decay e.gs

Answer 7

This can happen naturally in some soils, particularly water logged soils and in lakes and marshes

. When people over water their houseplants and flood the roots, anaerobic decay can occur, which can kill them

Question 8

How does anaerobic decay or decomposition provide us with fuel.

Answer 8

Together the methane and carbon dioxide produced are called biogas. This is a source of renewable energy

Question 9

Required practical
Investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change

Answer 9

1. Place 20 cm3 of fresh milk into three beakers
2. Decide the three temperatures you will investigate. Write these onto the sides of the beakers. They may be 5, 20 and 35°C.
3. Use universal indicator paper or solution to determine the pH of the milk in the three beakers
4. Cover each beaker in cling film and incubate at the appropriate temperature
5. Use universal indicator paper or solution to determine the pH of the milk in the three beakers after 24, 48 and 72 hours

Question 10

Rate of change on a graph formulae =

Answer 10

vertical change
________________
horizontal change