2017 AS Paper 1

Question 1

Name the bond between nucleotides

Answer 1

phosphodiester bond

Question 2

Function of DNA helicase and DNA polymerase

Answer 2

DNA helicase; breaks weak hydrogen bonds between bases

DNA polymerase; joins two nucleotides together forming phosphodiester bonds

Question 3

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

Answer 3

• ATP contains ribose, nucleotide contains deoxyribose
• ATP contains 3 phosphate groups, nucleotide contains 1

Question 4

Explain the purpose of boiling the agar

Answer 4

to prevent contamination of other bacteria

Question 5

Explain the purpose of transferring the same volume of liquid culture onto each agar plate

Answer 5

so same number of bacteria transferred to allow for comparison

Question 6

Name the process by which fatty acids and glycerol enter epithelial cells

Answer 6

diffusion

Question 7

Explain the advantages of lipid droplet and micelle formation

Answer 7

• droplets increase surface area so faster hydrolysis
• micelles carry fatty acids and glycerol through the membrane to the cell

Question 8

Role of golgi apparatus in the absorption of lipids

Answer 8

• golgi apparatus packs and modifies triglycerides
• it then combines triglycerides with proteins
• this is then packaged for release/exocytosis

Question 9

Explain the role of the heart in the formation of tissue fluid

Answer 9

contraction of the ventricles produces high blood pressure which forces water out of capillaries

Question 10

Suggest how a blockage in the lymphatic system could cause lymphoedema

Answer 10

excess tissue fluid builds up

Question 11

How to test for amino acids

Answer 11

biuret test

Question 12

Name the chemical element found in all amino acids that isn’t found in triglycerides

Answer 12

nitrogen

Question 13

Explain how the chromosome number is halved during meiosis

Answer 13

homologous chromosomes pair and one of each pair goes to each daughter cell

Question 14

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

Answer 14

• homologous pairs of chromosomes associate which forms a chiasmata
• equal lengths of alleles are exchanged producing a new combination of alleles

Question 15

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

Answer 15

• homogenise the sample of leaf tissue
• then centrifuge it at different speeds until you obtain the chloroplast fraction

Question 16

Mitochondrion vs Chloroplast features

Answer 16

• both have double outer membranes
• chloroplast has starch grains
• mitochondria has oxygen diffusing into it

Question 17

Give the function of a mitochondrion

Answer 17

site of aerobic respiration

Question 18

Give 3 properties of water that are important in biology

Answer 18

• high specific heat capacity
• used as a solvent to transport substances
• has hydrogen bonds between molecules

Question 19

Method used to produce solutions of different concentrations

Answer 19

dilution series

Question 20

Define species

Answer 20

a group of organisms that are able to produce fertile offspring

Question 21

Define species richness

Answer 21

the number of species in a community