Foundations in Biology Exam Questions

Question 1

Which statement describes triglycerides?
A They are broken down by condensation reactions.
B They are polymers of glycerol and fatty acids.
C They contain ester bonds.
D They contain glycosidic bonds.

Answer 1

C

Question 2

Which statement describes the properties or functions of cholesterol?
A It increases the fluidity of the phospholipid bilayer at high temperatures.
B It is an unsaturated fatty acid because it contains carbon–carbon double bonds.
C It is used to produce some hormones.
D It is very hydrophilic so is attracted to the fatty acid tails in the membrane.

Answer 2

c

Question 3

Which statement about the effect of temperature on enzyme-controlled reactions is not correct?
A At temperatures above 40 °C the rate of all enzyme-controlled reactions decreases.
B Increasing the temperature above the optimum changes the tertiary structure of the active
site.
C Increasing the temperature increases the kinetic energy of the enzyme and substrate.
D Increasing the temperature increases the probability of enzyme-substrate collisions.

Answer 3

A

Question 4

Which option is not a component of a chloroplast?
A Cristae
B DNA
C Ribosome
D Thylakoid

Answer 4

A

Question 5

Which option is the correct procedure for statistical analysis of the data collected by the class?
A Calculate the mean number of chloroplasts per cell in the high and low light intensity areas
and use a paired t-test.
B Calculate the mean number of chloroplasts per cell in the high and low light intensity areas
and use an unpaired t-test.
C Calculate the median number of chloroplasts per cell in the high and low light intensity areas
and calculate Spearman’s rank correlation coefficient.
D Calculate the median number of chloroplasts per cell in the high and low light intensity areas
and use a chi-squared test.

Answer 5

B

Question 6

The thermal properties of water allow organisms to live in an environment with relatively small
changes in temperature. These properties also make water efficient as a coolant, e.g. in sweating
or by absorbing large amounts of heat.
Outline how other properties of water are essential for sustaining life on Earth. (6 marks)

Answer 6

Chemical properties:
- Polar molecule due to the unequal sharing of electrons/dipole
- Hydrogen is slightly positive and oxygen is slightly negative
- hydrogen bonds between water molecules are weak
- large number of bonds collectively strong

Physical properties:
- lower density of ice than liquid water so ice
floats
- ice insulates (water below) / ice freezes
from top down
- cohesion
- adhesion
- high surface tension
- polar solvent
- transparant

Examples of how life is sustained:
- habitat for aquatic organisms
- buoyancy / support for fish
- fish obtain dissolved oxygen
- organisms can survive beneath ice
- ice is habitat for e.g. polar bears
- ice provides resting / breeding areas for
e.g. penguins / seals
- allow transpiration stream
- allows turgor pressure
- allows hydrostatic skeletons
- lubricant e.g. pleural fluid
- allows movement on water surface for e.g.
pond skaters
- cytosol of eukaryotic / prokaryotic cells
- medium for chemical reactions
- allows transport of dissolved substances
e.g. glucose in blood / e.g. dissolved
nutrients in oceans
- allows removal of metabolic waste
- allows light to penetrate

Question 7

The solution given to the student was prepared using 34.23 g of sucrose in 100 cm3
water.
The sucrose was measured on an electronic balance using the following procedure:
* mass of weighing boat empty = 10.55 g
* mass of weighing boat plus sucrose = 44.78 g.
The balance recorded masses to two decimal places with an uncertainty of ± 0.01 g.
Calculate the percentage uncertainty in the mass of sucrose.

Answer 7

total uncertainty = ±0.02 g
Uncertainty = 0.02 ÷ 34.23 (x 100) = 0.06 (%)

Question 8

Explain what is meant by pluripotent. (2 marks)

Answer 8

• can differentiate into
  any adult cell type/tissue type
• cannot form whole organisms/extra-embryonic tissues

Question 9

The scientists then repeated their experiments with adult stem cells taken from the skin
of patients with hypothyroidism. These cells were artificially transformed into pluripotent
stem cells (iPSCs).
The scientists concluded that use of human iPSCs would be safer than using human
ESCs to treat hypothyroidism.
Use your knowledge of stem cells to suggest one reason that supports and one reason
that does not support the scientists’ conclusion. (2 marks)

Answer 9

Support:
- Less risk of rejection

Does not support:
- adult stem cells may have accumulated mutations
- iPSCs may increase risk of cancer/tumour formation
- may still carry the allele for hypothyroidism

Question 10

Many processes in the body are controlled by enzymes.
Which of the options is an extracellular process controlled by enzymes?
A Conversion of fibrinogen to fibrin during blood clotting
B Digestion of a pathogen inside a lysosome
C DNA replication
D Movement of vesicles from the Golgi apparatus to the cell membrane

Answer 10

A

Question 11

Which statement about the secondary structure of a protein is correct?
A β-pleated sheets contain β-glucose.
B Disulfide bonds are not involved.
C Each single polypeptide is either an α-helix or a β-pleated sheet.
D Hydrogen bonds form between the R-groups of different amino acids.

Answer 11

B

Question 12

Cellulose is the main component of plant cell walls.
Which option is not a property of cellulose?
A High tensile strength
B Inflexible
C Insoluble in water
D Resistant to digestion by enzymes

Answer 12

D

Question 13

Glycogen is a large polysaccharide.
Which option describes the structure and function of glycogen?
A 1–6 glycosidic bonds are more accessible to enzymes than 1–4 glycosidic bonds so energy
can be released more quickly.
B Bonds between β-glucose residues are easily broken by enzymes.
C Exposed OH groups mean glycogen is soluble.
D Short branches allow more energy storage in a small space.

Answer 13

D

Question 14

Name the bond present in the primary structure of a protein. (1 mark)

Answer 14

Peptide bond

Question 15

State one feature, that shows that haemoglobin is a globular
protein. (1 mark)

Answer 15

• Spherical shape
• No fibres
• Contains prosthetic groups

Question 16

Outline the role of RNA polymerase in the production of the mRNA sequence in
Fig. 16.2.
Fig. 16.2 shows part of the mRNA sequence that codes for normal haemoglobin and
the corresponding sequence of amino acids. (2 marks)

Answer 16

• Adds RNA nucleotides
• Forms phosphodiester bonds between nuceotides

Question 17

In sickle cell disease, the mutated haemoglobin has a reduced ability to carry oxygen.
Some gene mutations do not affect protein function.
Use Fig. 16.3 (representation of the genetic code) and levels of protein structure to explain why some gene mutations do
not affect the function of a protein. (6 marks)

Answer 17

Mutations:
- genetic code is degenerate
- point mutation might code for the same
amino acid

Protein structure and function:
- haemoglobin function is dependent on
tertiary structure
- silent mutation would leave primary
structure unchanged
- unchanged primary structure would leave
tertiary structure unchanged
- substitution of amino acid with similar
properties to the original amino acid might
leave tertiary or secondary structure
unchanged
- mutation might change part of the tertiary
structure away from the functional part of
the protein, e.g. away from the active site
of an enzyme

Question 18

Yoghurt is a food produced from milk using microorganisms.
Yoghurt production involves two bacteria: Lactobacillus delbrueckii and Streptococcus
thermophilus.
(i) The bacteria convert the lactose present in milk into lactic acid.
Lactic acid is an important contributor to the flavour of yoghurt. Lactic acid also helps to
give yoghurt a longer shelf life than milk.
Suggest how lactic acid helps to extend the shelf life of yoghurt. (2 marks)

Answer 18

• Keeps the pH below optimum
• For bacterial enzymes

Question 19

Both bacteria also break down some of the protein casein, which is present in milk.
Name the product of protein breakdown and describe the type of reaction that takes
place. (2 marks)

Answer 19

Product: amino acid
Reaction: hydrolysis

Question 20

Mycoprotein foods contain protein.
The presence of protein in a solution can be detected using biuret reagent.
In the presence of protein, biuret reagent turns from blue to violet.
(i) A colorimeter can be used, along with biuret reagent, to determine the concentration of
protein in a solution.
Outline how to use a colorimeter to determine the concentration of protein in a solution. (4 marks)
(ii) State one alternative method for determining the concentration of protein in a solution. (1 mark)

Answer 20

i) - zero the colorimeter
- use known (concentration of protein) solutions
- plot calibration curve/absorbance vs concentration
- measure absorbance of (unknown) sample
- compare the absorbance of the unknown sample with the calibration
graph
- use appropriate filter for the shade of purple/biuret
ii) Biosensor

Question 21

Which of the options describes the path taken by proteins, such as digestive enzymes, that are
exported from a cell?
A Golgi apparatus rough endoplasmic reticulum secretory vesicle
B ribosome smooth endoplasmic reticulum Golgi apparatus
C rough endoplasmic reticulum Golgi apparatus secretory vesicle
D smooth endoplasmic reticulum ribosome Golgi apparatus

Answer 21

C

Question 22

Which of the statements about enzyme catalysed reactions is true?
A Binding of a substrate to the active site can weaken bonds in the substrate.
B Enzymes allow reactions to happen at a rate faster than the Vmax.
C Enzymes increase the rate of reactions by increasing the activation energy.
D Every 10 °C increase in temperature will approximately double the rate of all enzyme controlled
reactions.

Answer 22

A

Question 23

Liver is a rich source of the enzyme catalase.
The table below describes examples of three terms from the list below.
coenzyme, competitive inhibition, enzyme-product complex,
induced-fit, lock and key, non-competitive inhibition,
prosthetic group, secondary structure, tertiary structure.
Complete the table by choosing a term from the list that matches each example.
1. The haem molecule bound to each polypeptide
chain of catalase.
2. Binding of the hydrogen peroxide substrate to
catalase causes a change in the shape of the
active site of catalase.
3. Cyanide ions decrease the action of catalase
even at high concentrations of hydrogen
peroxide.

Answer 23

1. prosthetic group
2. induced fit
3. non-competitive inhibition

Question 24

Plant growth requires the production of new xylem cells.
Describe how new xylem cells are produced. (2 marks)

Answer 24

• produced in meristems
• by differentiation from stem cells

Question 25

Which of the options is a function of fibrous proteins?
A aids rigidity of membranes
B involved in cell signalling
C provides elasticity in alveoli
D speeds up reactions

Answer 25

C

Question 26

Explain how the structure of phospholipid molecules allows for the formation of plasma
membranes. (3 marks)

Answer 26

• phosphate on head is hydrophilic
• two fatty acid tails are hydrophobic
• heads orientate towards water/tails orientate towards other fatty acids/tails orientate away
  from water so a bilayer forms

Question 27

The permeability of plasma membranes can be investigated using beetroot.
Beetroot cells contain a red pigment. The red pigment leaks out of the cells only when the
plasma membrane has become damaged.
Some students investigated the effect of pH on the permeability of plasma membranes in
beetroot cells.
The students used a valid method for the investigation, which is outlined below:
* Equal-sized disks of beetroot were cut.
* The disks were each immersed in an equal volume of buffer solution.
* After a set time, the solution was stirred and the absorbance measured using a colorimeter.
* The procedure was replicated three times in each of six different pH buffers.The students concluded that the red pigment began to leak out of the beetroot cells at
any pH below pH 6.

i) Suggest and explain why a low pH might cause the red pigment to leak out of the
beetroot cells. (2 marks)

ii) Outline how the students could modify their investigation to get a more accurate value
for the pH at which the red pigment begins to leak out of the beetroot cells. (2 marks)

Answer 27

i) - a low pH denatures/changes tertiary structure of membrane proteins
- therefore membrane permeability to the pigment is
increased

ii) - use pH buffer range with narrower intervals
- pH buffers close to pH6 / between pH5 and pH6 /
between pH5 and pH7

Question 28

Which of the following statements, A to D, about differential staining is not true?
A Differential staining can distinguish between different organelles.
B Differential staining can distinguish between types of cell.
C Differential staining can distinguish between types of organism.
D Differential staining is a common feature of electron microscopy

Answer 28

D

Question 29

Which of the following statements, A to D, about microscopes is correct?
A A light microscope with an eyepiece lens magnification of × 10 and an objective lens
magnification of × 50 will have an overall magnification of × 60.
B Scanning electron microscopes and laser scanning confocal microscopes can both produce
three dimensional images.
C The maximum resolution of a scanning electron microscope is lower than that of a light
microscope.
D Transmission electron microscopes and laser scanning confocal microscopes can both
produce three dimensional images.

Answer 29

B

Question 30

Name the type of reaction that occurs when ATP is converted to ADP. (1 mark)

Answer 30

Hydrolysis

Question 31

A teacher told his students that the human body makes the equivalent of its own mass in
ATP every day.
Explain why, at the end of the day, only a small proportion of the students’ mass was
ATP. (2 marks)

Answer 31

• because ATP is broken down/hydrolysed to ADP
• ATP is constantly recycled
• ATP used to provide energy for metabolic processes, such as muscle contractions
• ATP is not stored long term/it is used immediately

Question 32

The student used a colorimeter to measure the concentration of each substance in the liquid
surrounding the cells.
The colorimeter had an analogue display. The reading was indicated by a needle moving
across a scale. The smallest divisions on the scale corresponded to 0.1 absorbance unit.
After the investigation the student suggested some improvements.
Match the improvement to the corresponding justification:
1. Use a colorimeter with a digital
display showing absorbance units
to 3 decimal places.
2. Check the zero value of the colorimeter with purified water
before use.
3. For each concentration, repeat the
measurement of the rate of reaction
three times and calculate a mean.
4. Ask students in several schools to
carry out the same investigation.

A) To assess repeatability
B) To assess reproducibility
C) To reduce systematic error
D) To reduce random error (uncertainty)
E) To increase resolution

Answer 32

1E
2C
3D
4B

Question 33

The student used the following method for the investigation:
Step 1: Extraction of pigments
* Take 0.5 g of fresh spinach and add 1 g of sand.
* Grind the mixture until it becomes a fine, light green powder.
* Transfer the powder to a test tube and add 2 cm3 of propanone.
* Stir for about 1 minute then allow to stand for another minute.
* Transfer the dark green upper layer with a pipette to a clean test tube and seal with
film when not in use.
Step 2: TLC analysis
* Hold the TLC plate carefully by the edges and avoid damaging the surface of the
plate.
* Draw a pencil line across the width of the TLC plate 1 cm from the bottom edge.
* Spot the extract on the pencil line using a pipette, one drop at a time, allowing the
spot to dry before adding the next drop.
* Place chromatography solvent in a jar so that it is no more than 0.5 cm deep.
* Lower the TLC plate into the jar and lean the top against the side of the jar. Make
sure the plate does not touch the sides of the jar anywhere else.
* Place a cap on the jar and allow the solvent to soak up the plate.
* When the solvent has reached a few mm from the top of the plate, remove the plate
from the jar and mark the position of the solvent front with a pencil.

(i) Explain why the method included the following precautions:
1. Hold the TLC plate carefully by the edges and avoid damaging the surface of the plate.
2. Make sure the plate does not touch the sides of the jar anywhere else. (2 marks)

ii) Suggest an advantage of working as quickly as possible in Step 1 (1 mark)

Answer 33

i) - hold TLC plate carefully
so that the movement of spots not affected by damage OR so that plates are not contaminated by fingerprints/oils from skin
- make sure plate doesn’t touch sides of jar because condensation/liquid/solvent on walls
of the jar may affect movement of
spots OR to avoid solvent/spots travelling in the wrong direction

ii) - to reduce damage/contamination of the photosynthetic pigments to reduce/avoid , evaporation of propanone/solvent

Question 34

Scientists have used FURA-2 to study the role of Ca2+ ions in the synapses of living nerve
tissue.
FURA-2 was injected into a single sensory neurone that was connected by a synapse to a
relay neurone.
FURA-2 fluorescence inside the neurone was observed using a confocal microscope.
(i) Explain one advantage of using a confocal microscope in this study. (1 mark)

Answer 34

• it can be used with living cells/thick cells

Question 35

The endosymbiosis theory suggests that mitochondria may have evolved from bacteria that
were taken inside other cells.
These cells then evolved into eukaryotes.
(i) Give two structural features of mitochondria that support this theory. (2 marks)

Answer 35

• length/size similar to that of a bacterium
• contain circular DNA
• contain 70S ribosomes
• may have plasmids
• have a double membrane

Question 36

Explain why early eukaryotes were able to grow more quickly than cells that did not
possess mitochondria. (3 marks)

Answer 36

Cells with mitochondria/early eukaryotes:
- would be able to respire aerobically
- this produces more ATP
- ATP needed for active transport/cell division /protein synthesis/DNA replication
- more ATP allows faster metabolic processes/reactions

Question 37

A student investigated the effect of different sugars on the respiration rate in yeast using the
following procedure.
* Prepare a stock solution of yeast containing 10 g of dried yeast in 250 cm3 of
pH5 buffer.
* Prepare solutions of each sugar containing 5 g of sugar in 250 cm3 of distilled
water.
* Keep the yeast and sugar solutions in a water bath at 35 ºC until required.
* Set up the apparatus with a 250 cm3 conical flask connected by a rubber tube
to a 100 cm3 gas syringe.
* Add 25 cm3 of yeast solution and 25 cm3 of sugar solution to the flask,
immediately connect the flask to the gas syringe and start the clock.
* Record the volume of gas produced after 30 s and then every 30 s for 7 min.
* Repeat the experiment 5 times for each different sugar.
* Prepare a fresh yeast solution for each set of sugars.
(i) Describe two precautions the student should take between each experiment to ensure
repeatable results. (2 marks)
(ii) The student’s procedure did not include a negative control.
Describe one negative control that the student could have used.

Answer 37

i) - rinse/change the flask
- stir yeast (stock) solution
- make the yeast stock solution from the same type of yeast
- ensure connection to gas syringe is tight
- check the temperature of , water bath/yeast (stock)
solution is 35 ºC

ii) - use boiled (and cooled) yeast
- use a buffer instead of yeast

Question 38

A light microscope can be used to observe yeast cells.
State the equipment that would be needed, in addition to a microscope, to measure the
average diameter of yeast cells. (1 mark)

Answer 38

• eyepiece graticule
• stage micrometer

Question 38

The student wanted to study the effect of the different sugars on the rate of growth of a yeast
population.
They used a colorimeter to measure the absorbance of a culture of yeast cells.
The absorbance of the yeast culture is proportional to the concentration of yeast cells.
As the yeast multiplied, it was necessary to dilute the sample to obtain a reading on the
colorimeter.
(i) Describe how the student could use 1 cm3 pipettes and 10 cm3 measuring cylinders to
dilute the sample so that it was 10 000 times less concentrated. (3 marks)

Answer 38

• need to make a total of four 1:10 dilutions/
  three further 1:10 dilutions
• 3 correct values of dilutions given between stages
  e.g.1:10 to 1:100
  -ensure mixing of yeast suspension at each stage

Question 39

Which of the following statements is/are evidence that DNA replication is semiconservative?
1 After one replication, the number of adenine nucleotides is equal to the number of guanine
nucleotides.
2 After two replications, two DNA molecules have one original and one new strand, and two
DNA molecules have two new strands.
3 After three replications, there are eight DNA molecules, only two of which have strands from
the original DNA.
A 1, 2 and 3
B only 1 and 2
C only 2 and 3
D only 1

Answer 39

C

Question 40

Which of the following, A to D, is true of a competitive enzyme inhibitor?
A binds to a site other than the active site
B can bind irreversibly to the active site
C changes the shape of the active site
D effects can be overcome by adding more substrate

Answer 40

D

Question 41

Which of the following, A to D, is not true about adult stem cells?
A They are found in bone marrow.
B They are not specialised.
C They are totipotent.
D They can be used as a renewing source of undifferentiated cells.

Answer 41

C

Question 42

Hydra is a small animal that lives in fresh water. When environmental conditions are
favourable, Hydra reproduces asexually. Large numbers of offspring can be produced in this
way.
Suggest why Hydra reproduces asexually when conditions are favourable. (2 marks)

Answer 42

• genetically identical offspring
• offspring produced rapidly/in large numbers
• all offspring will find conditions favourable/have
  same adaptations

Question 43

When conditions are not favourable, Hydra reproduces sexually. This often happens in the
winter.
Cells in the body wall produce sperms and eggs by meiosis.
Large numbers of sperms are released into the water. These sperms can fertilise eggs from
different individuals. Each egg forms a tough outer coat, and can lie dormant at the bottom of
the water until conditions improve.
(i) Explain how sexual reproduction in Hydra leads to genetic variation in the offspring. (6 marks)

Answer 43

• genetic variation is the variety of alleles
• offspring have alleles from more than one parent
• random fertilisation
• meiosis produces genetically unique gametes
• crossing over in prophase 1
• alleles swapped between non-sister chromatids
• base sequence of chromosomes is altered
• independent assortment/random segregation in metaphase 1
• also relevant in metaphase 2 if crossing over has occurred
• the sperm from one Hydra can fertilise an egg from any other individual Hydra
• the two Hydra can have different alleles
• sperm carried in water
• might travel large distances
• to unrelated Hydra