5.3 Energy and Ecosystems

Question 1

How does energy enter an ecosystem?

Answer 1

via light energy from the sun

Question 2

What are the 2 uses of glucose in an ecosystem?

Answer 2

storage as starch
convert into any carbon containing compound

Question 3

How is energy tranferred to the next trophic level?

Answer 3

by chemical energy transferred in biomass

Question 4

How is energy lost from a system?

Answer 4

heat energy via resp
chemical energy lost to dead organic matter

Question 5

What are the insoluble parts of an organism?

Answer 5

bones, fur, teeth, hair, feathers

Question 6

What is the effect of cellulose being indigestable?

Answer 6

primary consumers that eat plants can’t digest the cellulose, so it contributes as faeces in dead organic matter

Question 7

Why do birds/invertebrates pass on more energy than mammels?

Answer 7

invertebrates and birds are not endotherms so they have a lower rate of resp

Question 8

Why are carnivores more efficient at energy transfers?

Answer 8

Carnivores digest and absorb more of their food than herbivores which provides a higher proportion of usable energy
cellulose is difficult to digest

Question 9

What is the max no. of trophic levels in a food chain?

Answer 9

4

Question 10

What is photosynthetic efficiency?

Answer 10

a measure of how well a plant is able to harvest the light energy and convert it into chemical energy

Question 11

What are all the ways light is not absorbed into a plant?

Answer 11

absorbed by water
transmitted
reflected
light is the wrong wavelength (green light)
low CO2 conc for photosyn

Question 12

Why is light absorbed by water on a leaf?

Answer 12

water has a high latent heat of vapourisation for evapouration

Question 13

Why is some light reflected off a leaf?

Answer 13

thw waxy cuticle

Question 14

What is GPP?

Answer 14

the total amount of solar energy converted into chemical energy by primary producers (like plants) within a given area over a specific time

Question 15

What is NPP?

Answer 15

the chemical energy store that is left once resp losses have been accounted for and is available to primary consumers or herbivores

Question 16

What is the NPP and GPP equation?

Answer 16

NPP = GPP - R

Question 17

What is the net secondary productivity of consumers (N) equation?

Answer 17

N = I - (F + R)

I = chemical energy store of indigested food
F = energy lost in faeces and urine
R = energy lost in resp

Question 18

What are 2 ways biomass can be measured?

Answer 18

mass of carbon
or dry mass of tissue in an area

Question 19

How is primary and secondary productivity measured?

Answer 19

the biomass in a given area at a given time

Question 20

What happens to most of the sugars synthesised by plants?

Answer 20

used as resp substrate

Question 21

What is biomass?

Answer 21

the total mass of organic material, measured in a specific area over a set time period

Question 22

What units are used to measure biomass?

Answer 22

g/ m2

Question 23

What is a method for finding the dry mass of a plant?

Answer 23

heat and weight until a constant mass

Question 24

Why might it be useful to measure the dry mass of a sample rather than the fresh mass?

Answer 24

fresh mass can fluctuate due to water content fluctuating

Question 25

What is the equation for calculating the % efficiency of enegy transfer?

Answer 25

amount of biomass transferred / amound of biomass available x 100 = % efficiency of energy transfer

Question 26

What is primary producivity?

Answer 26

the rate at which plants or primary producers create new organic matter through photosynthesis

Question 27

What is secondary productivity?

Answer 27

the rate which consumers (animals) convert chemical energy in their food into their own biomass

Question 28

Explain why an increase in shoot biomass can be taken as a measurement of net primary productivity 

Answer 28

Represents dry mass / mass of carbon  Represents gross production minus respiratory losses 

Question 29

What is the net secondary productivity?

Answer 29

the energy avaiable to the next tropic level

Question 30

How can understanding energy transfers between tropic levels help farmers?

Answer 30

develop agricultural practises to maximise energy efficiency

Question 31

What are some agricultural practises that maximise energy efficiency?

Answer 31

- select crops with high photosynthetic efficiency - keep animal barns warm during cold seasons - reduce movement of livestock

Question 32

How does planting photosynthestic efficient crops reduce energy expenditure?

Answer 32

enhances GPP by maximising the energy captured by plants = increases energy available for consumption by higher trophic levels

Question 33

How does keeping animal barns warm reduce energy expenditure?

Answer 33

less energy used to maintain body temp of livestock energy can be allocated to growth and production

Question 34

How does restricting movement of livestock reduce energy expenditure?

Answer 34

lower resp rates for movement = lower resp losses in energy