Past Paper Questions

Question 1

Describe how you would decide the number of quadrants to use in order to collect representative data

Answer 1

Enough to do statistical test

Need to make sure work can be carried out in available time

Question 2

Explain why the rate of co2 production was higher when the apple slices were in nitrogen than when they were in the air

Answer 2

Respiring anaerobically
So produce less ATP

ATP production affects co2 production

Question 3

In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how

Answer 3

Light energy excited electrons in chlorophyll
Electrons pass down ETC
Electrons reduce carriers
ETC in thylakoids
Energy released 
ATP phosphorylation

Question 4

Explain how and why the efficiency of energy transfer is different at different stages in the transfer in an ecosystem

Answer 4

Efficiency lower in older animals and herbivores

Carnivores use more of their food than herbivores

Question 5

Explain how the intensive rearing of domesticated livestock increases net productivity

Answer 5

Slaughtered when still young

So more energy transferred to biomass

Question 6

Describe how microorganisms make carbon in starch available to plants

Answer 6

Release enzymes
Starch to smaller molecules
Respiration produces co2

Question 7

Explain why plants cannot use photosynthesis as their only source of ATP

Answer 7

Wouldn’t produce enough as only produces a little

Doesn’t produce ATP in the dark

Question 8

What does a small surface area to volume allow

Answer 8

The animal to retain heat

Question 9

What term is used to describe conditions which stay the same bell curve on the graph

Answer 9

Stabilising

Question 10

Describe how microorganisms make carbon in starch available

Answer 10

Excrete enzymes onto it
Starch to glucose
Respiration from digestion
Respiration produces co2

Question 11

If nitrogen gas is the substrate for an enzyme. What is the product?

Answer 11

Ammonia

Question 12

What does the Hardy-Weinberg principle predict?

Answer 12

Proportion of ALLELES
genetic change over time
Providing no mutations/migrations etc

Question 13

Explain the change in soil nitrate concentration shown in the graph
(Increases steadily)

Answer 13

Increase in dead organisms leading to increase in nitrification

Question 14

The ratio of dry biomass in animals to the dry biomass in seaweeds is always less than one. Explain why

Answer 14

Loss of energy between tropic levels

Levels as result of respiration

Question 15

Co2 concentration in air over 24 hours changes. Explain why

Answer 15

Plants respire in dark

Dark = no photosynthesis
Respiration occurs

Question 16

Describe how carbon in co2 becomes carbon in triose phosphate during the light independent reaction

Answer 16

Co2 combines with ribulose
Produces 2 GP
Reduced to TP using NADP
Energy from ATP

Question 17

Describe how microorganisms make carbon in dead worms available to cells in a leaf

Answer 17

Microorganisms are SAPROPHYTES
Excrete enzymes
Absorbs products of digestion
Co2 released when they respire
Co2 taken into leaves through stroma

Question 18

Explain meant by the term population

Answer 18

Number of organisms of a species in an area at a given time

Question 19

Explain what is meant by recessive allele

Answer 19

Only shown in phenotype when homozygous

Question 20

Measuring aerobic respiration in an experiment with a woodlouse. Explain why liquid moved to the left

Answer 20

Woodlouse takes up oxygen
Co2 given out is absorbed by the solution
Pressure decreases

Question 21

Experiment with woodlouse aerobic respiration.

What measurements should student take

Answer 21

Mass of woodlouse
Diameter of cross-sectional area
Position of liquid before and after certain time

Question 22

In animal experiment explain why type of food they’re given needs to be controlled

Answer 22

Different amount of protein etc may affect absorption

Question 23

In animal experiment explain why temperature needs to be controlled

Answer 23

Heat lost to maintain body temperature

Question 24

Describe and explain how succession occurs

Answer 24

Pioneer species
Change conditions
Enables other species to colonise 
Change in biodiversity
Stability increases so less hostile environment 
Climax community

Question 25

Advantages and disadvantages of biological control

Answer 25

Good as specific to one pest

Bad as doesn’t completely get rid of pest

Question 26

Give ways in which the properties of ATP make it a suitable source of energy

Answer 26

Releases energy in small amounts

Soluble

One quick hydrolysis step to release energy

Question 27

Explain why it’s necessary for humans to synthesise a large amount of ATP

Answer 27

Can’t be stored

Only releases small amount of energy at one time

Immediate source of energy

Question 28

Give advantages of using natural fertiliser over artificial fertiliser

Answer 28

Less leaching as slow release of nutrients

Contains wider range of elements

Question 29

Explain why scientists chose sample at random

Answer 29

Avoid bias

Allows statistical test

Question 30

Describe how co2 converted to organic substances during photosynthesis

Answer 30

Light independent reaction

Co2 combines with RUBP
produce GP
GP reduced to TP
Using reduced NADP
And energy from ATP