Energy Transfers

Question 1

What does biomass specifically refer to in biology?

Answer 1

Mass of carbon (organic compounds).

Question 2

How else is biomass measured in plants?

Answer 2

Dry mass of tissue per given area.

Question 3

What is the first step to remove water from a tissue sample?

Answer 3

Heat the sample at less than 100 °C.

Question 4

How do you know when to stop heating the sample?

Answer 4

When the mass stays the same after repeated weighing.

Question 5

What is Gross Primary Productivity (GPP)?

Answer 5

Chemical energy stored in plant biomass per area or volume.

Question 6

What process is GPP associated with?

Answer 6

Rate of photosynthesis.

Question 7

What is Net Primary Production (NPP)?

Answer 7

Chemical energy in biomass after subtracting respiratory losses.

Question 8

What is the formula connecting NPP, GPP, and respiration (R)?

Answer 8

NPP = GPP - R.

Question 9

What is the formula for net production of consumers?

Answer 9

N = I - (F + R).

Question 10

In this formula, what does I represent?

Answer 10

Energy ingested by the consumer.

Question 11

What does F stand for?

Answer 11

Energy lost in faeces.

Question 12

What does R represent?

Answer 12

Energy lost through respiration.

Question 13

Why is NPP important for ecosystems?

Answer 13

It provides energy for plant growth and reproduction.

Question 14

Who else benefits from NPP?

Answer 14

Other trophic levels like herbivores and saprobionts.

Question 15

What are typical units for expressing NPP?

Answer 15

kJ ha⁻¹ year⁻¹, kJ km⁻² year⁻¹, or kJ km⁻³ year⁻¹.

Question 16

Name one reason why producers trap only a low percentage of light energy.

Answer 16

Some light is reflected or absorbed by water vapour.

Question 17

Why else is light energy not efficiently trapped?

Answer 17

Some is reflected from producers or is the wrong wavelength.

Question 18

What about light transmission affects energy capture?

Answer 18

Light passes between chloroplasts or plants without being absorbed.

Question 19

Give one reason why most light is not used in photosynthesis.

Answer 19

Light is reflected away.

Question 20

What wavelength issue limits photosynthesis?

Answer 20

Light may be the wrong wavelength or frequency.

Question 21

How does light location affect photosynthesis?

Answer 21

Light misses chlorophyll or photosynthetic tissue.

Question 22

What environmental factors limit photosynthesis despite light?

Answer 22

Low CO2 concentration or unsuitable temperature.

Question 23

Why is the biomass of primary consumers less than producers?

Answer 23

Energy is lost as heat during respiration.

Question 24

What other energy losses reduce consumer biomass?

Answer 24

Energy lost in excretion (urine, CO2).

Question 25

How do indigestible parts affect biomass transfer?

Answer 25

They are egested to decomposers, not used for biomass.

Question 26

Why is some light energy not used in photosynthesis?

Answer 26

It fails to strike the leaf or is reflected.

Question 27

What is the approximate efficiency of photosynthesis in plants?

Answer 27

Around 2%.

Question 28

Name one way energy is lost after photosynthesis.

Answer 28

Respiratory loss.

Question 29

What causes energy loss in consumers?

Answer 29

Energy lost in excretion, faeces, or uneaten food.

Question 30

What is the approximate efficiency of energy transfer to consumers?

Answer 30

About 10%.

Question 31

Which animals have lower energy transfer efficiency?

Answer 31

Older animals, herbivores, primary consumers, and warm-blooded animals.

Question 32

Which animals use more of their food energy?

Answer 32

Carnivores.

Question 33

Why does slaughtering animals young increase net productivity?

Answer 33

More energy goes into growth before maturity.

Question 34

How does feeding concentrates improve productivity?

Answer 34

More food is absorbed; less is lost in faeces.

Question 35

How does movement restriction help net productivity?

Answer 35

Less energy used in movement; reduced respiratory loss.

Question 36

What does keeping animals indoors do?

Answer 36

Reduces heat loss and protects from predators.

Question 37

What genetic method improves livestock productivity?

Answer 37

Genetic selection for high productivity.

Question 38

Why must plants respire as well as photosynthesise?

Answer 38

Photosynthesis does not produce ATP in the dark.

Question 39

Why can't ATP made in photosynthesis be used everywhere?

Answer 39

Some plant tissues cannot photosynthesise.

Question 40

Why is ATP transport between cells limited?

Answer 40

ATP cannot be moved or stored across cells.

Question 41

What do plants need ATP for besides growth?

Answer 41

Active transport and synthesis of molecules.

Question 42

When is CO2 concentration highest near forest ground?

Answer 42

At night or in darkness.

Question 43

Why does photosynthesis stop at night?

Answer 43

It requires light (light-dependent reaction).

Question 44

What happens to CO2 at night in the forest?

Answer 44

Plants and organisms respire, releasing CO2.

Question 45

What happens to CO2 concentration during the day?

Answer 45

Plants absorb more CO2 than they release.

Question 46

How does CO2 concentration vary with height in daylight?

Answer 46

It decreases with height due to fewer leaves and less photosynthesis near the ground.

Question 47

What else influences CO2 concentration near the ground?

Answer 47

More animals producing CO2 and less light.