Ecosystems And Energy Transfers

Question 1

what is the source of energy for nearly all life on earth

Answer 1

the sun

Question 2

how do plants use the light energy that they absorb

Answer 2

• a small percentage of it is used to create glucose during photosynthesis
• they use some of the glucose immediately for respiration
• and store some of the rest of it in biomass

Question 3

what happens after a rabbit eats a plant

Answer 3

• it uses some of the energy it gets from the plant

- and some of the rest is stored in its body as biomass

Question 4

what happens after the fox eats the rabbit

Answer 4

• it gets some of the energy stored in the rabbits biomass

- and the chain of biomass transfer continues until the tertiary consumer is reached

Question 5

what is an example of energy being used at each stage of the food chain in order to keep animals alive and what happens to this energy

Answer 5

• respiration, which transfers energy for all life processes including movement
• a lot of the energy is transferred to the surroundings as heat

Question 6

why isnt energy used in respiration transferred to the next organism that eats the previous one

Answer 6

• because energy used in respiration isnt stored as biomass

- so it isnt transferred to the organisms in the next trophic level

Question 7

what is each stage in the food chain called

Answer 7

a trophic level

Question 8

does all the stored biomass get transferred to the next trophic level and why

Answer 8

• all of the stored biomass doesnt get transferred to the next trophic level
• because not all of the organism gets eaten such as bones
• and not all of the bits that get eaten can even be digested

Question 9

how is undigested material of the previous trophic level lost

Answer 9

by excretion of the faeces

Question 10

why do you hardly ever get food chains with more than 5 trophic levels

Answer 10

• because so much energy is lost at each stage that there is not enough left to support more organisms after four or five stages
• you also tend to get fewer organisms at each trophic level

Question 11

what does a pyramid of biomass show

Answer 11

how much the creatures at each level of the food chain would weigh if you put them together

Question 12

what does the pyramid of biomass also show due to a positive correlation

Answer 12

how much energy there is at each stage of the food chain

Question 13

what happens tot the mass of an organism as you go up one trophic level and why

Answer 13

• the mass goes down
• because most of the biomass is lost
• and so does not become biomass in the next trophic level up

Question 14

what are the names of the different levels in the pyramid of biomass

Answer 14

• the first level at the bottom is always the producer
• the second level is the primary consumer
• the third level is the secondary consumer and so on

Question 15

what should you make sure of when drawing a pyramid of biomass in an exam

Answer 15

• make sure the bars are drawn relatively to scale

- such as 5 squares equalling 1kg

Question 16

what formula do you use to calculate the energy lost between tropic levels next to each other

Answer 16

energy lost = energy available at previous level - energy transferred to next level

Question 17

what formula do you use to calculate the efficiency of energy transfer between trophic levels

Answer 17

efficiency = (energy transferred to next level / energy available at previous level) x 100

Question 18

how would you calculate the biomass lost between trophic levels

Answer 18

• use the same formula for calculating the efficiency
• but substitute the word ‘energy’ for ‘biomass’
• as they are pretty much the same thing (biomass is stored energy)

Question 19

what do the arrows on a food chain show you

Answer 19

the direction of energy transfer