p1 - 2017

Question 1

What is the function of the enzyme DNA helicase?

Answer 1

unwinding DNA and breaking hydrogen bonds

Question 2

What is the function of the enzyme DNA polymerase?

Answer 2

joins adjacent nucleotides

Question 3

Adenosine triphosphate (ATP) is a nucleotide derivative.

Contrast the structures of ATP and a nucleotide found in DNA
2

Answer 3

ATP has ribose + DNA nucleotide has deoxyribose

ATP has 3 phosphate groups + DNA nucleotide has 1 phosphate group

Question 4

Name the process by which fatty acids and glycerol enter the intestinal epithelial cell

Answer 4

diffusion

Question 5

Explain the advantages of lipid droplet and micelle formation
(3)

Answer 5

1. Droplets increase surface areas enzyme action
2. So faster hydrolysis of lipids
3. Micelles carry fatty acids and monoglycerides to intestinal epithelial cell

Question 6

Explain the role of the heart in the formation of tissue fluid
(2)

Answer 6

Contraction of ventricles produces high hydrostatic (blood) pressure

This forces water and some dissolved substances out of blood capillaries

Question 7

Suggest how a blockage in the lymphatic system could cause lymphoedema

Answer 7

Excess tissue fluid cannot be absorbed

Question 8

Which test could the scientists have used to identify that there are amino acids in
white wine?

Answer 8

Biuret

Question 9

Name the chemical element found in all amino acids that is not found in triglycerides

Answer 9

Nitrogen

Question 10

Explain how the chromosome number is halved during meiosis

Answer 10

Homologous chromosomes (pair);
2. One of each pair goes to each daughter cell

Question 11

What is the haploid number of chromosomes for this species of moss?

Answer 11

6

Question 12

Describe the process of crossing over and explain how it increases genetic
diversity
(4)

Answer 12

1. Homologous pairs of chromosomes associate
2. Chiasma form
3. Equal lengths of non-sister chromatids/alleles are exchanged
4. Producing new combinations of alleles

Question 13

Describe how you would use cell fractionation techniques to obtain a sample of chloroplasts from leaf tissue

(don’t get)

Answer 13

1. Macerate / homogenise / blend / break tissues / cells (in solution);
2. Centrifuge;
3. At different / increasing speeds until chloroplast fraction obtained;

Question 14

Give the function of a mitochondrion

Answer 14

The site of aerobic respiration reactions

Question 15

Give three properties of water that are important in biology

Answer 15

• is a solvent
• has a relatively high heat capacity
• has hydrogen bonds between molecules

Question 16

define species

Answer 16

A group of organisms that are able to produce fertile offspring

Question 17

define species richness

Answer 17

the number of different species in a community