As paper 2 test 1

Question 1

0 1 . 2 Describe how the production of messenger RNA (mRNA) in a eukaryote cell is different from the production of mRNA in a prokaryote cell.

Answer 1

Pre-mRNA (only) produced in eukaryote (cell);
Splicing (only) occurs in eukaryote (cell);
Introns removed in eukaryote (cell)
Introns not present in prokaryote (cell);

Question 1

What is a gene?

Answer 1

A sequence of DNA (nucleotide) bases that
codes for a polypeptide;

Question 2

Scientists produced a short, single-stranded, artificial nucleic acid, called PNA. The
PNA binds to a small section of DNA.
The scientists introduced PNA into cells and discovered that these cells produced
less mRNA than cells that did not contain PNA.
Suggest how PNA affected the transcription of the section of DNA.

Answer 2

1. PNA is complementary to DNA

PNA forms base pairs with DNA;
2. Preventing/reducing RNA polymerase
activity/binding

Prevents RNA nucleotides binding

Reducing/stopping transcription;

Question 3

0 1 box . 4 Describe the role of ATP in the process of translation in protein synthesis.

Answer 3

1. Releases/provides energy;
2. (So) peptide bonds form between amino acids
   (So) amino acid joins to tRNA;

Question 4

0 2 box . 1 What term is used to describe the different structures of α-glucose and β-glucose?

Answer 4

Isomer(ism); 1

Question 5

0 2 . 2 A student investigated the difference in the reducing sugar content of two fruit juices.
He performed a biochemical test on each fruit juice using Benedict’s solution. He
then used a colorimeter with each test result.
Describe how the results from the colorimeter can identify the fruit juice containing the
higher sugar content.

Answer 5

High(er) absorbance (has more sugar)
OR
Low(er) transmission (has more sugar);

Question 6

The student controlled variables in the test using Benedict’s solution.
Give two variables the student controlled

Answer 6

1. Benedict’s (solution) volume;
2. Benedict’s (solution) concentration;
3. (Fruit) juice volume;
4. (Water bath/water/solution) temperature;
5. Duration of heating (in water bath);

Question 7

Iodine solution stains fresh apple tissue black. When iodine solution is added to
apples stored for a week, the stain is less black.
The water potential of apple juice decreases when apples are stored.
Suggest why the water potential of apple juice decreases when apples are stored

Answer 7

1. Starch hydrolysed;
2. Maltose is soluble, (so reduces Ψ)
   OR
   Starch is insoluble

Question 8

0 4 box . 1 Describe how the process of meiosis results in haploid cells.
Do not include descriptions of how genetic variation is produced in meiosis.
[4 marks]

Answer 8

1. DNA replication (during late interphase);
2. Two divisions;
3. Separation of homologous chromosomes (in
   first division);
4. Separation of (sister) chromatids (in second
   division);
5. Produces 4 (haploid) cells/nuclei;

Question 9

A student dissected a sheep’s heart. He prepared a risk assessment on:
* carrying a scalpel
* using a scalpel.
Complete Table 3 by giving three control measures the student must use to reduce
the risks associated with carrying and using a scalpel.

Answer 9

1. Carry with blade protected
   OR
   Do not carry if likely to be jostled;
2. Cut away from body;
3. Cut onto hard surface;
4. Use sharp blade;
5. Disinfect/dispose of used scalpel (blade) as
   instructed;

Question 10

Suggest:
* a further investigation the scientist could do to confirm that the brightly coloured
stones had affected guppy behaviour
* a null hypothesis for the new investigation.

Answer 10

1. Repeat (the investigation) without stones
   OR
   Repeat (the investigation) with uniformly
   coloured stones;
2. Presence of stones has no effect on behaviour
   OR
   Colour of stones has no effect on beha

Question 10

0 8 Guppies are small fish with brightly coloured spots on their body. box
The number of spots on a guppy is controlled by genes.
A scientist investigated guppy breeding in a large population of guppies in a fish tank.
The fish tank contained brightly coloured stones. After each generation of breeding,
she counted the number of spots on every guppy.
Figure 9 shows her results.
Figure 9
0 8 . 1 The scientist concluded that the mean number of spots on the guppies changed in this
fish tank because the brightly coloured stones had affected the behaviour of the
guppies.
The guppies did not behave aggressively towards each other and their feeding
behaviour did not change.
Suggest one type of guppy behaviour that could be affected by the presence of
brightly coloured stones

Answer 10

Mating/courtship/sexual behaviour;

Question 11

3 The scientist repeated the investigation of guppy breeding in an identical fish tank, but
added predators of the guppies into the fish tank at the fourth generation of breeding.
Figure 10 shows her results.
Figure 10
Name the type of selection the scientist investigated in this fish tank.
Explain why this selection affected the frequency of alleles in the population of
guppies in this fish tank.
[4 marks]
Type of selection
Explanation

Answer 11

1. Directional;
2. Fish with more spots are more likely to be
   predated;
3. Alleles for (more) spots not passed on;
4. (So) frequency of (more) spots alleles
   decreases;