B17 Organising an ecosystem

Question 1

what is biomass?

Answer 1

the amount of biological matter in an organism

Question 2

what are producers?

Answer 2

organisms which can make food from raw materials during photosynthesis

Question 3

what does a general food chain look like?

Answer 3

producer –> primary consumer –> secondary consumer –> tertiary consumer

Question 4

describe the relationship between populations of predators and prey:

Answer 4

• if there is plenty of food, prey grow and reproduce so the population increases
• prey population goes up as there is plenty of food for them
• high numbers of predators eat a larger proportion of prey so the numbers fall
• there is now less food for predators so their numbers fall
• prey numbers go up as there are less predators and more food for from fewer animals

Question 5

what are decomposers?

Answer 5

microorganisms that break down waste products and dead bodies

Question 6

describe the stages of the water cycle:

Answer 6

• water evaporates
• it condenses as it rises to form clouds
• it is then precipitated onto the surface of the earth
• water passes through bodies, is released during respiration and decay
• it is released during transpiration in plants

Question 7

what are detritus feeders or detritovores?

Answer 7

animals that start off the process of decay

eg. maggots, worms and beetles

Question 8

what does decay recycle?

Answer 8

• it returns mineral ions to the soil
• it returns CO2 to the atmosphere for photosynthesis

Question 9

how is carbon returned to the atmosphere?

Answer 9

• respiration
• combustion
• decay

Question 10

how is carbon taken in from the atmosphere to be used by organisms?

Answer 10

photosynthesis takes in carbon from the atmosphere as CO2

Question 11

what is a consequence of too much combustion?

Answer 11

the levels of CO2 are increasing which increases global warming

Question 12

what are the correct conditions for decay?

Answer 12

• temperature (enzymes)
• moisture (rate of growth)
• oxygen (respiration)

Question 13

what is decay used by farmers for?

Answer 13

to produce compost as a natural fertiliser

Question 14

what happens if bacteria decompose material in anaerobic conditions?

Answer 14

methane is produced which can be used as a fuel

Question 15

what are the optimum conditions for biogas generators?

Answer 15

anaerobic
30 degrees C