EN: Energy Transfer in Ecosystems

Question 1

Producers

Answer 1

Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and minerals.

Question 2

Consumers

Answer 2

Organisms that obtain their energy by feeding on other organisms rather than using the energy of sunlight directly.

Question 3

Primary consumer

Answer 3

Those that directly eat producers.

Question 4

Secondary consumer

Answer 4

Those that eat primary consumers.

Question 5

Tertiary consumers

Answer 5

Those that eat secondary consumers.

Question 6

Saprobionts

Answer 6

Group of organisms that break down that break down the complex materials in dead organisms into simple ones.

Question 7

Food chain

Answer 7

A feeding relationship in which producers are eaten by primary consumers, which are eaten by secondary consumers, which are then eaten by tertiary consumers.

Question 8

Trophic level

Answer 8

A stage in the food chain.

Question 9

Food webs

Answer 9

Many food chains linked together.

Question 10

Biomass

Answer 10

Total mass of living material in a specific area at a given time.

Question 11

Why is fresh mass unreliable?

Answer 11

Contains varying amounts of water which will affect mass.

Question 12

Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and minerals.

Answer 12

Producers

Question 13

Organisms that obtain their energy by feeding on other organisms rather than using the energy of sunlight directly.

Answer 13

Consumers

Question 14

Those that directly eat producers.

Answer 14

Primary consumer

Question 15

Those that eat primary consumers.

Answer 15

Secondary consumer

Question 16

Those that eat secondary consumers.

Answer 16

Tertiary consumers

Question 17

Group of organisms that break down that break down the complex materials in dead organisms into simple ones.

Answer 17

Saprobionts

Question 18

A feeding relationship in which producers are eaten by primary consumers, which are eaten by secondary consumers, which are then eaten by tertiary consumers.

Answer 18

Food chain

Question 19

A stage in the food chain.

Answer 19

Trophic level

Question 20

Many food chains linked together.

Answer 20

Food webs

Question 21

Total mass of living material in a specific area at a given time.

Answer 21

Biomass

Question 22

Ecosystem

Answer 22

All the organisms in an area, including biotic and abiotic factors.

Question 23

Briefly, what happens in photosynthesis?

Answer 23

Plants use energy from sunlight and carbon dioxide to make glucose and other sugars.

Question 24

What can biomass also be thought of?

Answer 24

The chemical energy stored in the plant.

Question 25

What are the sugars produced in photosynthesis used for?

Answer 25

• Some used for respiration - to release energy for growth.
• Rest is used to make biological molecules - like cellulose- which makes up a plant’s biomass.

Question 26

What are the terms biomass can be measured in?

Answer 26

• Mass of carbon that an organism contains.
• Dry mass of its tissue per unit area.

Question 27

Dry mass

Answer 27

Mass of an organism with the water removed.

Question 28

All the organisms in an area, including biotic and abiotic factors.

Answer 28

Ecosystem

Question 29

Mass of an organism with the water removed.

Answer 29

Dry mass

Question 30

How would you obtain a dry mass sample?

Answer 30

• Sample of organism is dried - often in an oven set to a low temperature.
• Sample is weighed at regular intervals (eg every day).
• When the mass becomes constant all the water has been removed.

Results can be scaled up to give dry mass of the total populatio or area being investigated.

Question 31

What might a typical unit for dry mass be?

Answer 31

kg m^-2

Question 32

Compared to dry mass, what is the mass of carbon generally taken to be?

Answer 32

Mass of carbon is generally taken to be 50% of dry mass.

Question 33

How can the chemical energy store in dry mass be estimated?

Answer 33

Using calorimetry

Question 34

Describe the steps in bomb calorimetry:

Answer 34

• Sample of dry mass is weighed.
• Burnt in pure oxygen within a sealed chamber called a bomb.
• Bomb is surrounded by water bath.
• Temperature rise is measured - as we know how much heat is required to raise the temperature of 1g of water by 1^oC.

Question 35

What are the units for the energy released by burnt biomass?

Answer 35

kJ kg^-1

Question 36

Gross primary production (GPP)

Answer 36

Total amount of chemical energy converted from light energy by plants in a given area.

Question 37

What is the most common cause of gross primary production loss?

Approximately 50%

Answer 37

Respiratory loss - energy lost to the environment as heat when plants respire.

Question 38

Net primary production (NPP)

Answer 38

The chemical energy store left when losses to respiration have been taken into account.

Energy available for the plant for growth and reproduction.

Question 39

What is the equation for NPP for producers?

Answer 39

NPP = GPP - R

Question 40

Total amount of chemical energy converted from light energy by plants in a given area.

Answer 40

Gross primary production (GPP)

Question 41

The chemical energy store left when losses to respiration have been taken into account.

Energy available for the plant for growth and reproduction.

Answer 41

Net primary production (NPP)

Question 42

What are typical units for primary production?

Answer 42

kJ m^-2 yr^-1

Question 43

When primary production is expressed as a rate, what is it called?

Answer 43

Primary productivity.

Question 44

How might consumers lose energy?

Answer 44

• Not all parts of the food are eaten - bones, plant roots.
• Of ingested materials:
  • Some are indigestible - egested as faeces.
  • Energy is lost to environment through respiration or excretion of urine.

Question 45

How can the net production of consumers be calculated?

Answer 45

N = I - (F+R)

• I = chemical energy in ingested food.*
• F = chemical energy lost in faeces and urine*
• R = energy lost through respiration*

Question 46

Percentage efficiency equation:

Answer 46

(energy available after transfer / energy available before transfer) x 100