2010 Jan Unit 4

Question 1

A large size results in animal being adapted for breeding in colder conditions

Answer 1

Small surface area to volume ratio-more fat
Lose less heat-Insulation
When they are sitting on eggs

Question 2

Explain how natural selection has accounted for the effect of —on the percentage of —-

Answer 2

Better camouflaged

Resulting in greater survival and reproductive sucess

Question 3

The percentage of —- changed over a period of time. Use knowledge of climate change to suggest an explanation

Answer 3

Decrease in the coloured animal is not camouflaged/at disadvantage
Non coloured at an advantage

Question 4

Symmetrical graph. What type of natural selection is it. Evidence of this

Answer 4

Stablising

Few animals survive at the extremes

Question 5

What is meant by population

Answer 5

All organism of one species in a habitat at a particular time

Question 6

Describe how you would place the quadrats at random

Answer 6

Generate random numbers by drawing some from a hat

Use the numbers as coordinates to find where to position each quadrat

Question 7

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

Answer 7

Calculate running mean
When enough quadrats this shows little change
Enough to carry out a statistical test
A large number to make sure results are reliable

Question 8

Statistically signifcant

Answer 8

So not due to chance

Question 9

One step in which carbon dioxide is produced

Answer 9

Krebs Cycle/ Link reaction/ Pyruvate to Acetlycoenzyme A

Question 10

Explain how
a decrease in temperature would affect the rate of carbon dioxide production.
Anaerobic respiration

Answer 10

Respiratory reactions controlled by enzymes 
Rate decreases
Less kinetic energy
Fewer collisions
Fewer E-S substrates

Question 11

Pyruvic acid to Ethanol

Use this pathway to explain the part played by reduced NAD

Answer 11

Required H/e-/is reduction

NAD reduces Pyruvate

Question 12

The rate of carbon dioxide production was higher when the apple slices were in
nitrogen than when they were in the air. Explain why.

Answer 12

Respiring anarobically
Anaerobic respiration produces less ATP
More anaerobic respiration to produce same amount of ATP therefore more CO2

Question 13

Species X has a high rate of photosynthesis at high light intensities,. Species X is the first tree to become established in the succession Explain why?

Answer 13

Vegetation consists mainly of low growing species
few tress;
Species X has high rate of photosynthesis at high light intensity;
Species X grow fastest at high rate of photosynthesis at high light intensities;
Will outcompete other species Y/Z

Question 14

Species X has a high rate of photosynthesis at high light intensities. Graph Z is lower than X. Species X may change the environment so that it becomes more suitable for species Z.
Use the graph to explain why.

Answer 14

Produces shade/reduces light intensity;
Species Z grows best/photosynthesis best/ in low light intensity /
Species Z does not grow well / low rate of photosynthesis in high
light intensity;

Question 15

Explain why the biologists selected the hairs at random.

Answer 15

Avoids bias/allows statistical tests to be carried out;

Question 16

Explain why it was important to check the repeatability of the measurements.

Answer 16

Increases the reliability of the measurements;
If measurements are repeatable, differences less likely to be due
to measurement/personal error/ anomalies unlikely;

Question 17

Explain why a statistical test was necessary in analysing the results

Answer 17

(A statistical test) determines the probability of results being due to chance
Enables null hypothesis/description of null hypothesis to beaccepted/rejected;
Determines whether correlation/result is significant;

Question 18

Describe how and explain why the efficiency of energy transfer is different at different
stages in the transfer.

Answer 18

Some light energy fails to strike/is reflected/not of
appropriate wavelength;
Efficiency of photosynthesis in plants is low
Respiratory loss / excretion / faeces /
Loss as heat;
Efficiency of transfer approximately 10%;
Efficiency lower in older animals/herbivores/ primary
consumers
Carnivores use more of their food than herbivores;

Question 19

Explain how the intensive rearing of domestic livestock increases net productivity

Answer 19

Slaughtered when still growing/before maturity/while young so more energy transferred to biomass
Fed on concentrate controlled diet so higher proportion of (digested) food absorbed
Movement restricted so less respiratory loss/less energy used
Kept inside/so less heat loss / no predators
Genetically selected for high productivity