AS Biology Specimen question paper Paper 2

Question 1

Whats the missing anticodon

Answer 1

the missing anticodon

Question 2

Aspartic acid and proline are both amino acids. Describe how two amino acids differ
from one another. You may use a diagram to help your description.

Answer 2

Have different R group;

Question 3

Deletion of the sixth base (G) in the sequence shown in Figure 3 would change the
nature of the protein produced but substitution of the same base would not. Use the
information in Table 1 and your own knowledge to explain why

Answer 3

Substitution would result in CCA/CCC/CCU;
2. (All) code for same amino acid/proline;
3. Deletion would cause frame shift/change in all
following codons/change next codon from UAC
to ACC;

Question 4

Other than ethical reasons, suggest two reasons why they chose to use cats as model
organisms.

Answer 4

(Are mammals so) likely to have same
physiology/reactions as humans;
2. Small enough to keep in laboratory / produce
enough milk to extract;
3. (Can use a) large number;

Question 5

Before starting their experiments, the scientists confirmed that, like human breast milk,
cat’s milk also contained bile-activated lipase.
To do this, they added bile to cat’s milk and monitored the pH of the mixture.
Explain why monitoring the pH of the mixture could show whether the cat’s milk
contained lipase.

Answer 5

1. Hydrolysis of lipids produces fatty acids;
2. Which lower pH of mixture;

Question 6

What can you conclude from Figure 5 about the importance of bile-activated lipase in
breast milk?

Answer 6

. (Bile-activated lipase/it) increases growth rate
(of kittens);
2. Results for formula with lipase not (significantly)
different from breast milk/are (significantly)
different from formula milk alone;
3. Showing addition of (bile-activated) lipase is the
likely cause (of increased growth);
4. Lipase increases rate of digestion of
lipids/absorption of fatty acids;

Question 7

Can you conclude that the insect pest resistant to Bt toxin found in the years 2002 to
2005 was the same insect species? Explain your answer.

Answer 7

(No – no mark)
Graph/bar chart only shows number of species, not
the name of the species;

Question 8

One farmer stated that the increase in the use of Bt crop plants had caused a mutation
in one of the insect species and that this mutation had spread to other species of
insect. Was he correct? Explain your answer

Answer 8

(No – no mark)
1. Mutations are spontaneous/random;
2. Only the rate of mutation is affected by
environment;
3. Different species do not interbreed/do not
produce fertile offspring;
4. So mutation/gene/allele cannot be passed from
one species to another;

Question 9

(No – no mark)
1. Mutations are spontaneous/random;
2. Only the rate of mutation is affected by
environment;
3. Different species do not interbreed/do not
produce fertile offspring;
4. So mutation/gene/allele cannot be passed from
one species to another;

Answer 9

1. Initially one/few insects with favourable
   mutation/allele;
2. Individuals with (favourable) mutation/allele will
   have more offspring;
3. Takes many generations for (favourable)
   mutation/allele to become the most common
   allele (of this gene);