AS paper 1

Question 1

3 differences between ATP and nucleotides

Answer 1

1. ATP contains 3 phosphate groups, nucleotides only contain one
2. ATP has a ribose sugar, nucleotide has deoxyribose
3. ATP’s base is always adenine, nucleotide can have any

Question 2

explain the advantages of lipid droplet and micelle formation

Answer 2

droplets can increase surface area for faster hydrolysis and digestion
micelles carry fatty acids to epithelial cell

Question 3

how is golgi apparatus involved in absorption of lipids

Answer 3

modifies triglycerides and combines them with proteins
packages them for exocytosis

Question 4

explain role of heart in formation of tissue fluid

Answer 4

contraction of ventricles produce high blood pressure
this forces water out of the blood capillaries

Question 5

why would a student choose a t test

Answer 5

looking for a difference between 2 means

Question 6

explain how the chromosome number is halved during meiosis

Answer 6

homologous chromosomes
one of each pair goes to each daughter cell

Question 7

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

Answer 7

homologous chromosomes form a bivalent
chiasmata form
equal lengths of non sister chromatids are exchanged
produces new combo of allele

Question 8

Describe how you would use cell fractionation techniques to obtain a sample of
chloroplasts from leaf tissue. Do not include in your answer information about
any solutions.

Answer 8

homogenise the leaf tissue
centrifuge at increasing speeds until chloroplast fraction is obtained in pellet

Question 9

function of mitochondria

Answer 9

atp is made here
site of aerobic respiration

Question 10

The student produced the sucrose solutions with different concentrations from a
concentrated sucrose solution.
Name the method she would have used to produce these sucrose solutions

Answer 10

dilution series

Question 11

species

Answer 11

group of living organisms that can produce fertile offspring

Question 12

species richness

Answer 12

the number of different species in a community

Question 13

68% of all the fish caught in this investigation came from sample A.
A student thought this showed that sample A had a greater index of diversity than
any of the other samples.
It is not possible to draw this conclusion from the given data. Give reasons why

Answer 13

number of individuals in each species not known

almost all could be same species

other samples may have more individuals of each species

Question 14

Suggest and explain why AZT does not destroy HIV in the body but stops or
slows the development of AIDS

Answer 14

HIV is in the infected person’s dna
new HIV particles are therefore still made
AZT inhibits reverse transcriptase, so stops new cells of HIV from forming

OR

Slows / stops replication of HIV; Stops destruction of more / newly infected T cells; So immune system continues to work (and AIDS does not develop);

Question 15

Suggest and explain two advantages of using HAART

Answer 15

slows or stops development of AIDS bc HIV resistant to AZT is destroyed
OR
no new HIV particles made as HAART will interfere with viral protein synthesis

Question 16

Name the blood vessels that carry blood to the heart muscle.

Answer 16

coronary arteries

Question 17

Other than both being disaccharides, give one similarity and one difference between the structures of lactulose and lactose.

Answer 17

both contain galactose
lactulose contains fructose while lactose contains glucose

Question 18

name the biological molecule in cell wall

Answer 18

murein

Question 19

bond between glycerol and fatty acids within a triglyceride

Answer 19

ester

Question 20

Figure 5 shows a hierarchy. Explain how

Answer 20

smaller groups within larger groups
no overlap

Question 21

What is the proteome of a cell?

Answer 21

number of different proteins a cell is able to produce

Question 22

Starting with mRNA in the cytoplasm, describe how translation leads to the box production of a polypeptide.

Answer 22

1. mRNA associates with a ribosome / ribosome
   attaches to mRNA;
2. Ribosome moves to / finds the start codon /
   AUG;
3. tRNA brings / carries (appropriate / specific)
   amino acid;
4. Anticodon (on tRNA complementary) to codon
   (on mRNA);
5. Ribosome moves along to next codon;

Question 23

Describe the pathway taken by an oxygen molecule from box an alveolus to the blood

Answer 23

Oxygen molecule diffuses across the alveolar epithelium and endothelium of capillary into the blood.

Question 24

Not all mutations in the nucleotide sequence of a gene cause a change in the
structure of a polypeptide.
Give two reasons why.

Answer 24

triplets can code for the same amino acid- degenerate

occurs in introns

Question 25

what are monoclonal antibodies

Answer 25

antibody produced from cloned plasma cells

Question 26

Give one example of using monoclonal antibodies in a medical treatment.

Answer 26

cancer OR blocks antigens on the cell

Question 27

Explain why it is more useful to calculate an index of diversity than to record species richness.

Answer 27

measures population size of each species so useful because may be many of some species

Question 28

Suggest how the scientist measured the rate of water flow in the river.

Answer 28

time to fill container of known volume

Question 29

would not be seen using an optical microscope. why?

Answer 29

light has a longer wavelength so, lower resolution

Question 30

Name an organelle found in both a chloroplast and a prokaryotic cell.

Answer 30

ribosome

Question 31

Describe and explain the advantage of the counter-current principle in gas exchange across a fish gill.

Answer 31

water and blood flow in opposite directions maintains concentration gradient of oxygen diffusion along the length of capillary

Question 32

Explain how the active site of an enzyme causes a high rate of reaction

Answer 32

lowers activation energy induced fit causes active sites to change shape enzyme substrate complex causes bonds to break and release energy

Question 33

Describe two other ways in which all dipeptides are similar and one way in which they might differ.

Answer 33

similarities--two r groups, carboxyl group differences- different r groups