5-3 Energy and ecosystems

Question 1

What is an ecosystem?

Answer 1

• An ecosystem includes all the organisms living in a particular area as well as all the non-living elements of that particular environment.

Question 2

What is a niche?

Answer 2

• Each species particular role in its habitat.

Question 3

What are organisms that cannot synthesise their own food called?

Answer 3

• Heterotrophs.

Question 4

Which ways can chemical food energy be lost?

Answer 4

• Uneaten parts.
• Decay of dead material
• Excretion
• Exothermic reactions

Question 5

How can the efficiency of energy transfer between trophic levels be calculated?

Answer 5

• Percentage efficiency = energy available after the transfer / energy available before the transfer x 100

Question 6

How can biomass be measured?

Answer 6

• Mass of carbon or dry mass per given area per given time.

Question 7

Why is dry mass used?

Answer 7

• Wet mass can vary too much.

Question 8

What is used to estimate dry biomass?

Answer 8

• Calorimetry.

Question 9

What is net primary productivity (NPP)?

Answer 9

• The rate at which energy is transferred into the organic molecules that make up new plant biomass, that is the chemical energy store in plant biomass after respiratory losses to the environment have been taken into account.

Question 10

What is gross primary productivity (GPP)?

Answer 10

• The rate at which energy is incorporated into organic molecules in the plants in photosynthesis, that is the chemical energy store in plant biomass, in a given area or volume, in a given time.

Question 11

What is the formula for NPP?

Answer 11

• NPP = GPP-R

Question 12

What is the formula for net production of consumers?

Answer 12

• N = I – F+R
• N = Net production of consumers
• I = Chemical food energy.
• F = Chemical food energy lost to environment in faces and urine
• R = Chemical food energy lost through respiration to the environment.