2017 AS Paper 1

Question 1

Function of DNA helicase

Answer 1

Breaking hydrogen bonds between bases causing DNA to unwind

Question 2

Function of DNA polymerase

Answer 2

Joins adjacent DNA nucleotides

Forms phosphodiester bond

Question 3

Difference between ATP and DNA

Answer 3

ATP - Ribose
DNA - Deoxyribose

ATP - 3 phosphate groups
DNA - 1 phosphate group

ATP - base always adenine
DNA - nucleotide base varies

Question 4

Purpose of boiling agar

Answer 4

Kill other bacteria

Question 5

Why is it beneficial to transfer same volumes of liquids during bacteria practical

Answer 5

Same number of bacteria transferred TO allow comparison

Question 6

How do fatty acids and glycerol enter the intestinal epithelial cell during absorption

Answer 6

Diffusion

Question 7

Advantage of lipid droplet

Answer 7

Droplets increase SA for lipase
So faster hydrolysis of lipids

Question 8

Advantage of Micelles

Answer 8

Micelles carry fatty acids and glycerol through membrane

Question 9

How is golgi apparatus involved in lipid absorption

Answer 9

Modifies triglycerides

Combines triglycerides with proteins

Forms vesicles

Question 10

Role of the heart in the formation of tissue fluid

Answer 10

Contraction of ventricles produces high blood pressure

Which forces water and dissolved substances out of blood capillaries

Question 11

How can a blockage in lymphatic system cause issues

Answer 11

Excess tissue fluid builds up

Question 12

How is the chromosome number halved during meoisis

Answer 12

Homologous chromosome pair

One of each pair goes to each daughter cell

Question 13

Describe the process of crossing over and how genetic diversity increases as a result

Answer 13

Homologous pairs of chromosomes associate

Chiasmata form

Equal lengths of chromarids are exchanged

Producing new combinations of alleles

Question 14

Describe how to use cell fractionation to obtain different organelles

Answer 14

Homogenise cells in solution

Put solution in centrifuge

At different speeds until organelle is obtained

Question 15

Name the properties of water and their advantages

Answer 15

Metabolite - in condensation reactions

Solvent - so metabolic reactions can occur

High specific heat capacity - so buffers changes in temperature

Large latent heat of vaporisation - so provides a cooling effect

Cohesion between water molecules - so supports columns of water

Question 16

Define species

Answer 16

Group of organisms that are able to produce fertile offspring

Question 17

Define species richness

Answer 17

Number of different species in a community

Question 18

Why may HIV treatments not destroy HIV but stop development of AIDS instead

Answer 18

Person with HIV has HIV DNA

New HIV are still made

Drugs inhibit reverse transcriptase

Which stops/slows HIV replication

Stops destruction of more T cells