1.

The structure and properties of the cell membrane control which molecules can move into or out of
the cell.

(a) The phospholipid bilayer plays an important role in this control of movement of molecules.
Explain why the phospholipid molecules form a bilayer.

…………………………………….…………………………………….……………………………..

……….…………………………………….…………………………………….……………………….

…………….…………………………………….…………………………………….………………….

……………………….…………………………………….

………………………………………………..

(3)
…..……….…………………………………….…………………………………….………...…………

………….…………………………………….…………………………………….………………….…

(b) The table below describes four methods by which molecules or ions can move through the
cell membrane.

Method by which molecules or ions move

through the membrane
Description of the method
A B C D

Direction of movement from higher concentration

to lower concentration of the molecule

ATP required

Membrane proteins involved

Molecule or ion transported by this method Water Na+ ions glucose oxygen

Identify the method of movement by placing a cross in the correct box in the table below.

(3)

1 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (c) A student carried out an experiment to investigate the effect of alcohol on the permeability of
beetroot cell membranes. Beetroot cells contain a red pigment.
One cube of beetroot was placed in a tube containing 5 cm3 of water and left for 30 minutes.
After 30 minutes the cube of beetroot was removed and the intensity of the colour of the liquid
was measured using a colorimeter.
A colorimeter is an instrument that can be used to measure the intensity of the colour of a
liquid.
The procedure was repeated using four different concentrations of alcohol instead of water.
The results are shown in the table below.

(i) Using the information in the table, describe the effect of alcohol on the permeability of beetroot
cell membranes.

As the concentration of alcohol increases the permeability of beetroot cell membranes

increases.

(2)

(ii) The temperature of the solutions and the size of the beetroot cubes should be controlled in this
investigation.
Explain how each of the following would affect the results of this investigation.

An increase in temperature…………………………………….…………………………………….…

………………………..……….…………………………………….…………………………………….

……………………….………………………………………….…………………………………….

…………………………….…………….…………………………………….

…………………………………A decrease in size of the beetroot cube….………………….

(4)
…………………….…………….…… ……………………….………………………………………….

…………………………………….……………………….……………………….

…………………………………….…………………………..……………………….

………………………………………….…………………………………….……

2 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (Total marks for question 1 = 12)

2 In mammals, most of the oxygen molecules are transported as oxyhaemoglobin by red blood cells.
At the respiring tissues, oxygen dissociates from haemoglobin and diffuses to the surrounding cells.

The diagram below shows the tertiary and quaternary structure of a haemoglobin molecule.

(a) Explain how the tertiary and quaternary levels of protein structure of the haemoglobin molecule
contribute to its role in the transport of oxygen.

…………………………………….…………………………………….…………………………..……..

……….…………………………………….…………………………………….

………………………….…………….…………………………………….

…………………………………….………..…………….……………………….

…………………………………….……………………………………………

…..……….…………………………………….…………………………………….………..….………

.…………….…………………………………….…………………………………….………..…………

.…………….…………………………………….…………………………………….………..…………

…………….…………………………………….…………………………………….………..……….

…….……………………….…………………………………….

……………………………………………

…..……….…………………………………….…………………………………….………..….…….…
(3)
.…………….…………………………………….…………………………………….………..…………

.…………….…………………………………….…………………………………….………..…………

…………….…………………………………….…………………………………….………..…….……

3 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (b) At high altitudes, the partial pressure of inspired oxygen is considerably lower than at sea level.
This means that the partial pressure of oxygen in the blood is also much lower at high altitudes
than at sea level.
The graph below shows an oxygen dissociation curve of adult oxyhaemoglobin.

With reference to the graph, calculate the difference in percentage saturation of haemoglobin at
sea level, where the partial pressure of oxygen is 13.0 kPa, and at a higher altitude, where the
partial pressure of oxygen is 6.2 kPa.

Show your working.

answer ...................................................... % (2)

(c) After spending time at altitude, a person can become acclimatised. One feature of acclimatisation
is an increase in the red blood cell count.
Explain the importance of the increase in the red blood cell count.

…………………………………….…………………………………….…………………………..

……..……….…………………………………….…………………………………….

………………………….…………….…………………………………….

…………………………………….………..…………….……………………….

…………………………………….………………………………………………..………. (2)

4 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 …………………………………….…………………………………….………..….

………………………………...…….…………………………………….………………………………

(d) Tobacco smoking can have an effect on the transport of oxygen by haemoglobin.
The graph below shows oxygen dissociation curves with and without the presence of carbon
monoxide (CO).

With reference to this graph, describe the effect of carbon monoxide on the cardiovascular
system.

…………………………………….…………………………………….…………………………..……..

……….…………………………………….…………………………………….

………………………….…………….…………………………………….

…………………………………….………..…………….……………………….

…………………………………….………………………………………………..……….
(3)
…………………………………….…………………………………….………..….

………………………………...…….…………………………………….

………………………………………

(Total marks for question 2 = 10)

5 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 aorta

3 The diagram shows the heart and blood vessels at three stages of the cardiac cycle.

(a) (i) Name the blood vessels labelled F and G.

F inferior vena cava
(2)
G aorta

(ii) Suggest which stage of the cardiac cycle is shown at K.

(1)
Atria systole

(b) Describe how blood is moved through the heart and then into the blood vessels between stages
H and J of the cardiac cycle.

......................................................................................................................................................

......................................................................................................................................................

..

......................................................................................................................................................
(3)

6 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 ......................................................................................................................................................

..

......................................................................................................................................................

(c) The table shows the speed of blood flow in three blood vessels.
Blood vessel Speed of blood flow in cm per second
aorta 40.00
lung capillary 0.03
vena cava 15.00

(i) Blood has to travel 20 cm from a person’s heart to their renal artery.
Calculate the time taken for blood to flow from this person’s heart to their renal artery.
Show your working.

time = .............................................................. s (2)

(ii) Explain how the speed of blood flow in the lung capillary affects gas exchange.

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

...................................................................................................................................................... (2)

.....

(Total marks for question 3 = 10)

Question 4 begins on page 8

4 Over 20% of the population of the UK is classified as obese. Obesity is a significant risk factor in the
development of cardiovascular disease (CVD).

(a) One way of estimating if a person is obese is to find their Body Mass Index (BMI).

7 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 Body Mass Index is calculated using the formula below.

Mass in kilograms
BMI =
(height in metres) 2

The table below provides the range of BMI values for different categories of people.
Category BMI range

Very severely underweight less than 15.0

Severely underweight from 15.0 to 15.9

Underweight from 16.0 to 18.4

Normal (healthy weight) from 18.5 to 24.9

Overweight from 25.0 to 29.9

Obese Class I (moderately obese) from 30.0 to 34.9

Obese Class II (severely obese) from 35.0 to 39.9

Obese Class III (very severely obese) over 40.0

(i) Calculate the BMI of a person who has a mass of 95 kg and a height of 1.75 metres.

95
1.75²

Answer 31.0 (1)

(ii) Use your calculated value and the information in the table to find the category of this person.

Category Obese class 1 (moderately obese) (1)

* (iii) People in this category are more likely to develop high blood pressure than people with a
healthy weight.
Explain why someone who has a high blood pressure is at a significantly higher risk of
developing CVD.

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

8 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 ......................................................................................................................................................

.....

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......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

.... (4)

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......................................................................................................................................................

......................................................................................................................................................

..

(b) Suggest one piece of medical advice that could be given to someone who does not have high
blood pressure but who is obese.

Explain why this will help to reduce their risk of developing CVD

Medical

advice: ......................................................................................................................... ................

.......................................................................................................................................

Why this will reduce the risk of developing CVD:

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................
(3)
...

(c) The graph below shows the death rates from CVD for men from 4 different European
countries.

9 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (i) Using the information in the graph, calculate the difference in the death rate of males as
deaths per 100000 between the years 1970 and 1990, in Finland.

answer =……………………………. (2)

(ii) Using the information in the graph, discuss the statement that death rates from CVD are
falling.

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

...

......................................................................................................................................................
(3)
......................................................................................................................................................

......................................................................................................................................................

...

(Total marks for question 4 = 14)

5 Lactase is an enzyme that catalyses the hydrolysis of lactose.

(a) (i) The diagrams show symbols for lactase, lactose and the monosaccharides of lactose.

10 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (1)

(ii) Which of the following are the monosaccharides present in lactose?

A fructose and sucrose
B galactose and glucose
C glucose and fructose
D sucrose and galactose (1)

(b) The graph shows the energy changes for the hydrolysis of lactose, with and without lactase.

Which row in the table describes line P and identifies the letter that shows the decrease in
activation energy due to lactase?

11 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (1)

(c) The graph shows the relationship between substrate concentration and the rate of reaction of
lactase.

(i) Explain why substrate concentration affects the rate of reaction.

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................
(2)
....

(ii) The reaction rate (V) at each substrate concentration can be calculated using the formula

Vmax is the maximum rate of reaction

12 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 K is the substrate concentration when the rate of reaction is half the rate of Vmax
S is the substrate concentration.

Calculate the reaction rate (V) at a substrate concentration of 4 a.u.

answer ..............................................................
(2)

(Total marks for question 5 = 07)

6 Nucleic acids include DNA and RNA.

(a) Each single strand of a DNA molecule is synthesised from mononucleotides.
Draw a diagram to show two mononucleotides joined together in a single strand of DNA.

Use the symbols shown for each component in your diagram.

Phosphate group Base

Pentose sugar Bond

(3)

(b) The diagram represents part of a DNA molecule.

The pitch is the length of one complete turn in the double helix. There are 10 base pairs in one pitch.
(i) Calculate the distance between one base and the next base on one strand of DNA.

13 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 Give your answer to an appropriate number of significant figures.

Answer .............................................................. nm (1)

(ii) The diagram shows the structure of thymine and four other bases, P, Q, R and S.
Bases P and S can form three hydrogen bonds each and bases Q and R can form two
hydrogen bonds each.

Explain which of the four bases P, Q, R or S is adenine.

......................................................................................................................................................

......................................................................................................................................................
(2)
......................................................................................................................................................

...

(c) Compare and contrast the structure of messenger RNA (mRNA) with the structure of transfer
RNA (tRNA).

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......................................................................................................................................................

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.....

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14 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 ......................................................................................................................................................
(4)
......................................................................................................................................................

......................................................................................................................................................

......

(Total marks for question 6 =10)

7 In the late 1950s, Meselson and Stahl performed some important experiments. These experiments
provided evidence to support the idea that new DNA was synthesised by semi-conservative replication.

(a) Meselson and Stahl’s experiments involved growing bacteria in culture media containing either
heavy nitrogen (15N) or light nitrogen (14N). The DNA was then extracted from the bacteria.

The diagram below shows the position of the DNA band in the centrifuge tube when the DNA
was labelled with the heavy isotope of nitrogen, 15N

The bacterial culture was then allowed to reproduce using nucleotides containing the normal
isotope of nitrogen (14N).
(i) Place a cross in the box below next to the tube showing the correct pattern of DNA after the (1)
bacteria have divided once.

(ii) Place a cross in the box below next to the tube showing the correct pattern of DNA after the (1)
bacteria have divided twice.

15 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 (b) Cystic fibrosis is a recessive condition caused by mutations in the CFTR gene.
Several alleles of the CFTR gene have been identified. Put a cross in the box to complete
each of the following sentences.
(i) A gene is a sequence of nucleotides that contains (1)
A hexose sugars and the bases A, C, G and T
B hexose sugars and the bases A, C, G and U
C pentose sugars and the bases A, C, G and T
D pentose sugars and the bases A, C, G and U

(ii) An allele is a form of a gene that (1)

A always affects the phenotype
B never affects the phenotype
C affects the phenotype only in a heterozygous genotype
D sometimes affects the phenotype when it is a recessive allele

(iii) In the space below, draw one family pedigree to show all the possible outcomes when both
parents are heterozygous for cystic fibrosis.
Use the symbols shown in the key.

(3)

(c) Cystic fibrosis and other genetic disorders can be detected using prenatal testing.
Describe how one named method of prenatal genetic testing can be carried out.

......................................................................................................................................................

......................................................................................................................................................

16 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 ..

......................................................................................................................................................
(3)
......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

....

(Total marks for question 7 =10)

8 Cocaine is an addictive drug and its frequent use increases the risk of a heart attack as cocaine
affects the levels of a number of blood clotting components, including von Willebrand factor. It is one
of the thirteen components, such as thrombin and fibrinogen that are involved in blood clotting.

(a) Put a cross in the box that completes each of the following statements.
(i) The role of thrombin in blood clotting is to (1)
A stimulate the release of prothrombin from platelets
B catalyse the conversion of fibrinogen to fibrin
C stimulate the release of thromboplastin from platelets
D catalyse the conversion of fibrin to fibrinogen

(ii) The ion required in the conversion of prothrombin to thrombin is (1)

A calcium C potassium
B chloride D sodium

(iii) Blood clots form only when required because the clotting factors used are (1)
A pre-synthesised in an active form in the blood
B present in an inactive form in the blood
C synthesised in an active form when required
D synthesised in an inactive form when required

* (b) The diagram below shows two functions of von Willebrand factor.

Using the information in this diagram and your own knowledge of the blood clotting process,
suggest why frequent cocaine use could increase the risk of a blood clot forming

......................................................................................................................................................

17 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020

 ......................................................................................................................................................

..

......................................................................................................................................................

......................................................................................................................................................

..

...................................................................................................................................................... (4)

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

....

(Total marks for question 8 = 07)

Total marks for this paper is 80

18 AS BIOLOGY UNIT 1 MOLECULES, DIET, TRANSPORT AND HEALTH MOCK 2020