Jun 2015 Unit 2

Question 1

What is the function of the coronary arteries?

Answer 1

1. (Carry) oxygen/glucose;

2. (To) heart muscle/tissue/cells

Question 2

The rise and fall in blood pressure in the aorta is greater than in the small arteries.
Suggest why

Answer 2

1. (is) close/directly linked to to the heart/ventricle / pressure is higher/is very high;
2. (Aorta has) elastic tissue;
3. (Aorta has) stretch/recoil

Question 3

Give two differences in the variation in body length of male and female thorny lizards

Answer 3

1. Females are (generally) longer/larger whereas males are shorter
2. Females show a greater range than the males

Question 4

The ecologists also determined the index of diversity of lizards in an oil palm plantation
next to the woodland area. They found fewer species of plant in the oil palm plantation.
Lizards feed on plants and insects.
Explain why fewer species of plant would lead to fewer species of lizard in the oil palm
plantation.

Answer 4

(Fewer plant species) – no mark

1. (So) few(er) habitats/niches;
2. (So) lower diversity of insects / fewer insect species/fewer insect types;
3. (So) fewer food sources /

Question 5

Give two ways in which the structure of starch is similar to cellulose

Answer 5

1. Are polymers

2. Contain glucose

Question 6

Give two ways in which the structure of starch is different from cellulose.

Answer 6

(Starch)

1. Contains α/alpha glucose;
2. is helical not straight

Question 7

Suggest and explain one other way in which sieve cells are adapted for mass transport.

Answer 7

1. Cytoplasm is at the edge so there is more space/room

2. (So) easier/more flow/

Question 8

Suggest and explain one other way in which companion cells are adapted for the transport of sugars between cells.

Answer 8

1. Mitochondria release energy/ ATP/
   site of respiration;
2. For active transport/

Question 9

Describe the role of DNA polymerase in DNA replication

Answer 9

Joins nucleotides

Question 10

Other than being smaller, give two ways in which prokaryotic DNA is different from eukaryotic DNA.

Answer 10

DNA is circular

No introns

Question 11

Humans and grasshoppers have very similar percentages of each base in their DNA but
they are very different organisms.
Use your knowledge of DNA structure and function to explain how this is possible.

Answer 11

1. Have different genes;
2. (So bases/triplets) are in a different
   sequence/order;
3. (So) different amino acid(sequence/coded for)

Question 12

The DNA of the virus is different from that of other organisms.
Use Table 2 and your knowledge of DNA to suggest what this difference is.
Explain your answer.

Answer 12

1. A does not equal T / G does not equal C;
2. (So) no base pairing;
3. (So) DNA is not double stranded/is single stranded;

Question 13

Give three ways in which courtship behaviour increases the probability of successful mating.

Answer 13

1. Recognise/identify/attract same species;
2. Recognition/attraction of mate/opposite sex;
3. Indication of /fertility

Question 14

Suggest how the scientists could determine if the recorded natural song (L) was less effective than the natural song.

Answer 14

1. Use a (real) male (with intact wings/no wing removed);

2. Determine (percentage) response (of females compared withL)

Question 15

A student concluded from Table 3 that the number of chirps and ticks is essential for successfully stimulating courtship behaviour.
Do these data support this conclusion? Explain your answer

Answer 15

1. Lowest/only 30% courtship with no
song/K/
2. Reducedcourtship when no ticks/M /
there is some courtship when no
ticks/M;
3. Reduced courtship when no chirps/N
/ there is some courtship when no
chirps/N;
4. (So) courtship must involve a visual
stimulus/other factor involved

Question 16

The events that take place during interphase and mitosis lead to the production of two genetically identical cells. Explain how

Answer 16

1. DNA replicated;
2. Semi-conservative replication
3. sister chromatids;
4. move to opposite ends of cell;

Question 17

The student cut thin sections of tissue to view with an optical microscope.
Explain why it was important that the sections were thin.

Answer 17

1. To allow (more) light through;

2. A single layer(s) of cells to be viewed;

Question 18

Complete colour blindness occurs at a higher frequency on Pingelap than in the USA.
Use the information provided to explain why

Answer 18

1. Genetic bottleneck;
2. Less genetic diversity
3. so there is inbreeding
4. High(er) chance of inheriting allele

Question 19

A mutation can lead to the production of a non-functional enzyme. Explain how.

Answer 19

1. Change/mutation in base
2. Change in amino acid
   sequence/primary structure (of
   enzyme);
3. Change in hydrogen/ionic/disulfide
   bonds;
4. Change in the tertiary
   structure/shape;
5. Change in active site;
6. Substrate not complementary/cannot
   bind (to enzyme/active site) / no
   enzyme-substrate complexes form;

Question 20

One way in which the stringent response gives resistance to this antibiotic is by stopping
cell division.
The scientists concluded that stopping cell division is not the only way in which the
stringent response gives resistance to this antibiotic.

Answer 20

Despite stopping the cell division

the SR strain was still more resistant, therefore there is another factor.

Question 21

The stringent response involves a number of enzyme-catalysed reactions.
Explain how scientists could use this knowledge to design drugs that make the treatment
of infections caused by the SR strain more successful.

Answer 21

Make a non-competitive inhibitor which changes the shape of the active site.

Question 22

The scientists removed the ovaries from the mice for the investigation. They also gave
the mice injections of the substrate of aromatase each day.
Explain why these steps were necessary.

Answer 22

1. Removes (main/largest) source of oestrogen

2. (Allows) oestrogen to be controlled

Question 23

The scientists predicted that fulvestrant would be more effective when given with anastrozole than when given alone.
Use the information provided to suggest why they predicted this.

Answer 23

1. (Anastrozole) prevents/reduces oestrogen production;

2. (Fulvestrant) stops remaining oestrogen binding

Question 24

The scientists used tumour area as an indicator of tumour size.
Explain why tumour area may not be the best indicator of tumour size and suggest a more reliable measurement.

Answer 24

Tumour area does not take in to account the depth of the tumour
More realiable measurement would be volume of tumour

Question 25

The scientists repeated the investigation but this time they did not give the drugs until
week 9.
Suggest why they gave the drugs at week 9, rather than at week 5.

Answer 25

1. Allows tumours to grow/develop/form;

2. To see if the drugs can be used to treat the tumours rather than preventing the formation of tumours.

Question 26

Another group of scientists is currently using these drugs in human trials. However, the
control group is not being given a placebo.
Suggest why a placebo is not being given and what is being given to this group instead

Answer 26

1. The patients are already ill and not giving them a drug may exacerbate their illness.
2. Use normal cancer drugs