Energy And Ecosystems

Question 1

What are the features of producers?

Answer 1

• photosynthetic
• autotrophic
• green plants

Question 2

What is the role of decomposers in the food chain?

Answer 2

• to break down decaying material and release nutrients back into cycle

Question 3

Why is most of the suns energy NOT absorbed by photosynthesis?

Answer 3

• light is reflected
• light does not strike chlorophyll
• light is wrong wavelength
• photosynthesis may be limited by another factor

Question 4

Why is only a small amount of energy transferred to next organism at each trophic level?

Answer 4

• not all of organism is eaten
• not all consumed material is digested
• lost as heat from respiration
• lost through excretory products

Question 5

Net production =

Answer 5

Gross production - respiratory losses

Question 6

Energy transfer =

Answer 6

Energy available after transfer

Energy availed before transfer X100

Question 7

What are the units for energy transfer?

Answer 7

KJm-2year-1

Question 8

What are the drawbacks of pyramids of number?

Answer 8

• do not take into account size of organism

- small organisms can be difficult to count

Question 9

Why are pyramids of biomass measured with dry mass?

Answer 9

Water content in organisms can be variable

Question 10

What are the drawbacks of pyramids of biomass?

Answer 10

• sample has to be dead, small sample may not be representative
• organisms can have same dry mass but contain different amounts of energy
• seasonal differences are not taken into account

Question 11

What do pyramids of energy show?

Answer 11

Energy loss at each trophic level

Question 12

What are the units for pyramids of biomass

Answer 12

Gm-2 (on land)

Gm-3 (in water)

Question 13

What are the units for pyramids of energy?

Answer 13

KJm-2year-1

Question 14

What is an agricultural ecosystem?

Answer 14

Ecosystems made up of domesticated animals and crops to produce food

Question 15

What additional energy is required in agricultural ecosystems?

Answer 15

• food for farmers

- fossil fuels for machinery

Question 16

Why do agricultural ecosystems have higher productivity than natural ecosystems?

Answer 16

• have more energy sources (solar+)
• climax community is prevented from forming
• pesticides and herbicides are used to ensure max growth of desired plant/animal

Question 17

What are the features of pesticides?

Answer 17

• cost effective
• bio-degradable
• not accumulate
• specific to target pest

Question 18

What are the disadvantages of biological pesticides?

Answer 18

• effect is not immediate

- may become a pest

Question 19

What are the disadvantages of chemical pesticides?

Answer 19

• always have effect on non-target species
• pests can develop resistance
• has to be applied regularly

Question 20

How do pests affect productivity?

Answer 20

• weeds compete plants for water, space, nutrients etc
• insects may damage leaves, reduce photosynthesis
• animals may eat crop

Question 21

What is the aim of intensive farming?

Answer 21

To convert the smallest amount of food energy into greatest quantity of animal mass

Question 22

What are some features of intensive farming?

Answer 22

• reduced movement, less energy is used in muscle contraction
• controlled feeding, optimum amount for max growth and minimal wastage
• warm environment, reduce heat loss
• hormones and antibiotics used