5.3 Energy and ecosystem

Question 1

In a food chain/ ecosystem who are the producers, and why

Answer 1

Plants since they’re able to produce their own carbohydrates using CO2

Question 2

What is a trophic level

Answer 2

Each stage in a food chain

Question 3

How can energy be lost from trophic level to trophic level

Answer 3

• Respiration
• Excretion

Question 4

What is the energy remaining for the next trophic level called

Answer 4

Biomass

Question 5

How can biomass be measured

Answer 5

• Measuring mass of carbon per given area
• Measure the dry mass of tissue per given area

Question 6

What does GPP stand for

Answer 6

Gross Primary Production

Question 7

What is GPP / what does it measure

Answer 7

The chemical energy store in plant biomass, in a given area. It’s the total energy resulting from photosynthesis

Question 8

What does NPP stand for

Answer 8

Net Primary Production

Question 9

What is NPP/ what does it measure

Answer 9

The chemical energy store in plant biomass taking into account the energy that will be lost due to respiration

Question 10

What is the equation linking NPP, GPP, and R

Answer 10

NPP=GPP-R

Question 11

Is the NPP or the GPP the energy left over that is available to the plant to create new biomass and therefore available to the next trophic level in a food web

Answer 11

The NPP because it takes into account of the energy lost by respiration

Question 12

What is the equation for next production of consumers

Answer 12

N=I-(F+R)

Question 13

In the equation N=I-(F+R), what do the letter stand for

Answer 13

• I energy ingested in food
• F chemical energy lost to the environment in faces and urine
• R energy lost in respiration
• N Net production of consumers

Question 14

To figure out the unit of rates of productivity, what 3 things must be included

Answer 14

• The units for energy
• Per unit area
• Per year

Question 15

When adding units to rates of productivity, why must we record data over an entire year

Answer 15

To take into account the impact seasons will have on rain, light and heat- so provides an annual average to allow fair comparisons between environments

Question 16

Averagely, how much energy is laid down as biomass between each trophic level

Answer 16

About 10%

Question 17

What type of food is indigestible

Answer 17

Cellulose

Question 18

Why do primary consumers contribute a larger proportion of their energy to dead organic matter rather than to respiration

Answer 18

Since they tend to eat plants which contain cellulose which is indigestible so ends up as faeces and lost from the system as dead organic matter for the decomposers

Question 19

Who passes on more energy ? Mammals or invertebrates

Answer 19

Invertebrates because they aren’t endotherms so use up less glucose so more is available to lay down as biomass for the trophic level

Question 20

What is the max number of trophic levels in a food chain

Answer 20

Five but tends to only be 4 since there is not enough energy to support another trophic level

Question 21

What is photosynthetic energy

Answer 21

The measure of how well a plant can capture light energy and convert it into chemical energy

Question 22

What are the 5 ways why light energy isn’t always used in photosynthesis

Answer 22

• Reflected (waxy cuticle)
• Green light isn’t absorbed
• Transmitted (doesn’t hit the chlorophyll molecule)
• Some light energy absorbed by water
• Low carbon dioxide concentrations for photosynthesis so plant does not absorb unnecessary light