Jun 2016 Unit 2

Question 1

Explain what is meant by a phylogenetic group.

Answer 1

(Grouped according to) evolutionary links/ history/ relationships / common ancestry

Question 2

What is meant by species?

Answer 2

1. Able to reproduce;
2. To produce fertile
   offspring;

Question 3

Explain what the information in Table 2 suggests about the phylogenetic relationships between these tigers.

Answer 3

1. South China and Sumatran tigers share a more recent
   common ancestor;
2. (because) identical/same/matching (nucleotide) sequences;

Question 4

What term is used to describe the structure of a protein made of two or more polypeptides?

Answer 4

Quaternary (structure)

Question 5

Describe the role of haemoglobin in supplying oxygen to the tissues of the body

Answer 5

1. Oxyhaemoglobin formed/ haemoglobin is loaded/
   uptakes/associates/binds with oxygen in area of higher ppO2 / in gas exchange surface/lungs/gills;
2. (oxygen) unloaded/dissociates from/released (in area of lower ppO2 / in capillaries/to cells/tissues)

Question 6

Explain the advantage to a person with anaemia of the change shown in the oxygen dissociation curve

Answer 6

1. (Anaemia curve shifted to right) haemoglobin has lower affinity for oxygen / binds less tightly;
2. releases more oxygen / oxygen is released quicker / oxygen dissociates/ unloads more readily to muscles/tissues/cells;
3. (For) respiration;

Question 7

What is meant by species diversity?

Answer 7

Number of species in a ecosystem

Question 8

Give two pieces of information needed to calculate an index of diversity for a community.

Answer 8

1. Number of (organisms of) each species;

2. Total number of organisms (of all species) / Total number of species;

Question 9

A scientist investigated the effect sewage entering a river had on the distribution of organisms living in the river. Where sewage entered the river, he found a high density of organisms but a low index of diversity.
Suggest how sewage entering the river could explain the scientist’s findings.

Answer 9

1. Described effect of sewage (eg oxygen depletion/is toxic/kills);
2. Prevents some/many species colonising/ reproducing/remaining;
3. Sewage is food source for (individuals of) some/a few/species;
4. (So) increase only in their numbers;

Question 10

Explain how the second set of results affects the ability of the scientists to make any conclusions about the effect of sewage on the index of diversity.

Answer 10

1. Results are not repeatable / are not representative / unreliable / conflict / contradict;
2. Can’t make any conclusions;

Question 11

Suggest the additional steps that should be taken by the scientists before they are able to make any conclusions about the effect of sewage entering this river

Answer 11

Do repeats to find a pattern

Question 12

Name the structure through which gases enter and leave the body of an insect.

Answer 12

Spiracle

Question 13

Name the small tubes that carry gases directly to and from the cells of an insect.

Answer 13

Tracheoles

Question 14

Explain the movement of oxygen into the gas exchange system of an insect when it is at rest.

Answer 14

1. Oxygen used in (aerobic) respiration;
2. (so) oxygen (concentration) gradient (established);
3. (so) oxygen diffuses in

Question 15

A scientist investigated the effect of abdominal pumping on the pressure in the tubes
and the volume of carbon dioxide released by the insect.Figure 3 shows his results.

Describe and explain these results.

Answer 15

1. Abdominal pumping/pressure in tubes linked to carbon dioxide release;
2. (Abdominal) pumping raises pressure in body;
3. Air/carbon dioxide pushed out of body /air/carbon dioxide moves down pressure gradient (to atmosphere);

Question 16

Describe and explain the appearance of chromosome K in cell C.

Answer 16

1. (Chromosomes consist of) two chromatids connected at centromere;
2. (Because) DNA has replicated;

Question 17

Explain what is happening at point J in cell B.

Answer 17

1. Crossing over / exchange of alleles /lengths of DNA / recombination;
2. Between (chromatids of) homologous chromosomes

Question 18

Use information from all three cells in Figure 4 to explain how the number of chromosomes in cell D was produced.

Answer 18

1. Separation/segregation of pairs/homologous chromosomes;

Question 19

Explain why some cells contain a mass of DNA between 1 and 2 arbitrary units.

Answer 19

(DNA) replication taking place/not finished

Question 20

Describe how temporary mounts of leaves are made.

Answer 20

1. Thin slice/section;

2. Put on slide in water / solution / stain

Question 21

Describe how the scientist could have used the temporary mounts of leaves to determine the mean number of chloroplasts in mesophyll cells of a leaf.

Answer 21

1. Select large number of cells / select cells at random;
2. Count number of chloroplasts;
3. Divide number of chloroplasts by number of cells

Question 22

There are many different types of cell in a leaf, each with its own function.
What term is used to describe a structure such as a leaf?

Answer 22

organ

Question 23

What is the name of a position of a gene on a chromosome?

Answer 23

Locus

Question 24

What is meant by genetic diversity?

Answer 24

Differences in DNA

Question 25

What do these data show about the differences in genetic diversity between these breeds of dog?

Answer 25

1. Jack Russell (genetic) diversity is (significantly) greatest; 2. Bull terrier (genetic) diversity is (significantly) smallest / is most inbred; 3. Miniature terrier and Airedale terriers are similar; 4. Standard deviations do not overlap

Question 26

Miniature terriers were first bred from bull terriers in the 19th century. Suggest one explanation for the observed difference in genetic diversity between miniature terriers and bull terriers.

Answer 26

1. (Bull terrier) breeding has included a genetic bottleneck/ small population/more inbreeding/ greater selection (pressure); 2. Reduced number of different alleles/size of gene pool;

Question 27

The sport scientists concluded that the three types of meal had no major effect on maximum percentage increase in blood flow in the mesenteric artery. What else can be concluded from their results?

Answer 27

1. Time taken to reach maximum blood flow varied widely/significantly; 2. Quickest after a carbohydrate-only meal;

Question 28

Suggest the advantage of the change in blood flow in the mesenteric artery during exercise.

Answer 28

1. More blood flows to (skeletal) muscles (during exercise); 2. (supplying) more oxygen / glucose / removing more carbon dioxide/ lactic acid/ heat; 3. Prevents anaerobic respiration and build up of lactic acid

Question 29

The sport scientists concluded people should not do vigorous exercise after a meal. Does the information from Table 5 and Figure 7 support this conclusion?

Answer 29

Immediate effect of exercise after meal 1. Meal increases blood flow in (mesenteric) artery AND exercise decreases blood flow in (mesenteric) artery; Overall effect on blood circulation 2. Insufficient blood (flow to small intestines / muscles); Effect on blood flow of type of meal 3. Carbohydrate meal quick(er) / during exercise; Effect of reduced blood flow on cells 4. (More) anaerobic (respiration) / lactic acid produced; Consequence for person of changed blood flow 5. Less absorption (of digested food) /

Question 30

Blood leaving the kidney eventually returns to the kidney. | Describe the pattern of blood circulation in a mammal that causes blood to return to the kidney.

Answer 30

1. (blood flows from kidney along) renal vein to vena cava; 2. (along) vena cava to right atrium/side of heart; 3. (along) pulmonary artery to lungs; 4. (along) capillaries to pulmonary vein; 5. (along) pulmonary vein to left atrium/side of heart; 6. (along) aorta to renal artery (to kidney); 7. Blood may pass through several complete circuits before returning to kidney;

Question 31

Suggest two hypotheses the scientists were testing in this investigation.

Answer 31

1. Type of feed affects (antibiotic) resistant bacteria (in animals); 2. (Antibiotic) resistant bacteria infect /are passed on to animals/farmer / resistant bacteria are passed between animals;