Paper 1 Questions

Question 1

State the function of a cell wall (1)

Answer 1

Supports and strengthens the cell

Question 2

Name the subcellular structure involved in the translation of genetic material in protein synthesis (1)

Answer 2

Ribosomes

Question 3

Describe the role of a sperm’s acrosome in fertilisation (2)

Answer 3

• contains enzymes (1)
• that digest through the membrane of the egg cell (1)

Question 4

Explain why the membrane of an egg cell changes its structure immediately after fertilisation (2)

Answer 4

• to prevent other sperm cells from getting in (1)
• which ensures the offspring ends up with the right amount of DNA (1)

Question 5

Describe the purpose of the adjustment knobs of the microscope (1)

Answer 5

Bring sample into focus by moving the stage or the objective lens up/down (1)

Question 6

The potatoes of a potato plant develop underground.
Explain one difference in the sub-cellular structures in a cell in the potato and those in a cell in the leaf of the potato plant. [2]

Answer 6

• no chloroplasts (in the potato) (1)
• (as there is no light) for photosynthesis / potato cells do not photosynthesise / ORA (1)

Question 7

A student investigated mitosis in the root tip of a garlic plant. The student squashed the root tip on a microscope slide to spread out the cells, but could not see the chromosomes. State what could be added to make the chromosomes more visible (1)

Answer 7

A/n (iodine) stain (1)

Question 8

Describe how cancer develops in the liver (2)

Answer 8

Answer including any two from:
- mutations in DNA (1)
- cell division is uncontrolled (1)
- leading to a formation of a tumour/growth/mass of cells (1)

Question 9

Describe the function of meristems in the growth of a plant (2)

Answer 9

• (meristem cells) are undifferentiated (1)
• (meristem cells) divide/ produce more cells (1)
• by mitosis (1)

Question 10

Describe two processes that occur in cells during prophase (2)

Answer 10

• chromatids condense (1)
• identical chromatids joined (1)
• nuclear membrane breaks down (1)

Question 11

Describe two genetic similarities a cell going through mitosis would have (2)

Answer 11

• same genes / DNA/ alleles (1)
• diploid (1)

Question 12

Explain how the size of the pupil of the eye changes when a torch is shone into the eye of a person (3)

Answer 12

• pupil gets smaller (1)
• iris (1)
• gets bigger (1)

Question 13

Describe how an impulse passes from a relay neurone to a motor neurone (3)

Answer 13

• impulse triggers release of a chemical (1)
• neurotransmitter (1)
• neurotransmitter diffuses (1)
• across the synapse (1)
• new impulse triggered in motor neurone (1)

Question 14

Explain the function of a reflex arc (2)

Answer 14

• process that occurs in response to danger (1)
• which bypasses the brain (1)
• so there is a faster transmission / response / allows a quick reaction (1)
• to protect the body from harm (1)

Question 15

Describe the role of sensory neurones (2)

Answer 15

• transmit electrical impulses (1)
• from receptors to CNS (1)

Question 16

Name and describe the roles of the main enzymes used in genetic engineering [4]

Answer 16

The main enzymes used in genetic engineering are…
Restriction enzymes; [1 mark]
(DNA) Ligase; [1 mark]
Plus one of the following

(Restriction enzymes) cut DNA in a specific place/base sequence; [1 mark]
(creating) sticky ends; [1 mark]
Plus one of the following

(Ligase) anneals/rejoins/sticks lengths of DNA/sticky ends back together; [1 mark]
(when) inserting a gene / length of DNA into another eg. a vector; [1 mark]

Question 17

Explain the meaning of the term ‘vector’ in genetic engineering [2]

Answer 17

The term ‘vector’ when used in genetic engineering, means…
One of the following:
An organism / length of DNA eg. a virus / plasmid; [1 mark]
Into which a separate gene/length of DNA/allele can be inserted; [1 mark]
Plus

To insert a gene into the required cell(s); [1 mark]

Question 18

Describe the advantages of producing plants by tissue cloning [2]

Answer 18

• many plants produced (1)
• quicker than sexual reproduction (1)
• genetically identical/ clones produced (1)
• with the desired characteristics (1)
• plants from {endangered/rare} plants (1)

Question 19

Describe the reasons why the anatomy of the pentadactyl limb suggests that bats and cats evolved from a common ancestor [2]

Answer 19

• same structure of bones/examples of bone structure (1)
• (structure is) unlikely to have occurred more than once during evolution / common ancestor had {the pentadactyl limb structure/similar limb structure} (1)

Question 20

Explain one way in which the spread of TB can be prevented or reduced [2]

Answer 20

• {cough/sneeze} into a tissue/ avoid close contact with infected people/ avoid living in cramped conditions [1]
• because spread of TB is airborne droplets/ TB is spread through air [1]
  OR
• vaccination/ immunisation [1]
• to provide immunity/ reduces chances of a person getting infected [1]
  OR
• treat infected people with antibiotics [1]
• reduces infected people [1]

Question 21

Peas contain small amounts of fat.
Describe a test to identify fat. [2]

Answer 21

An answer linking:
* mix the food in ethanol and pour into water (1)
* white emulsion forms (1)

Question 22

The lytic pathway is part of the lifecycle of the Ebola virus.
After infection of the host cell, components of the virus are produced.
Describe the next stages of the lytic pathway. [2]

Answer 22

A description including:
* virus particles are assembled (1)
* virus lyses the cell / virus exits the cell (1)

Question 23

Amylase is produced by salivary glands and the pancreas.
Explain why amylase is not produced in the stomach. [3]

Answer 23

An explanation linking:
* the stomach is {acidic/low pH/pH 2}(1)
* which will denature the {amylase/enzyme} (1)
* changes the shape of the active site/substrate will not {bind/fit} into the active site (1)

Question 24

Give two aseptic techniques the scientist should use when taking samples from a bacterial culture. [2]

Answer 24

• wash hands/wear gloves (1)
• keep lid on the samples/only remove the lid for a short time (1)
• work close to a Bunsen flame (1)
• use sterile equipment (1)

Question 25

Cancer Research UK found that many people do not realise that obesity is linked to an increased risk of developing cancer.
In the body, fat tissue sends signals that cause other cells to divide.
Describe how this could cause cancer to develop. [3]

Answer 25

• (cells are triggered to divide) by mitosis (1)
• this division is uncontrolled (1)
• creates a mass/large number of cells /tumour (1)

Question 26

A student used the method shown in Figure 3 to compare the mass of DNA extracted from strawberry fruit cells and from kiwi fruit cells.
1. crush the fruit cells in a buffer solution
2. filter to separate the soluble DNA from the cell fragments
3. add ethanol
State why ethanol was used. [1]

Answer 26

To precipitate the DNA (1)

Question 27

Describe the changes that occur in the eye when a bright light is directed into the eye. [2]

Answer 27

• pupil becomes smaller (1)
• the iris changes shape (1)
• correct light intensity is detected by {retina /rods / cones} (1)

Question 28

Describe two processes that occur in cells during prophase. [2]

Answer 28

• chromatids condense (1)
• identical chromatids are joined (1)
• nuclear membrane breaks down (1)

Question 29

Infections with HIV can result in the death of a person because the T helper cells are destroyed. Explain how infection with HIV results in the T helper cells being destroyed [3]

Answer 29

• HIV DNA becomes incorporated into the T helper cell’s DNA [1]
• HIV particles are made/ virus replicates [1]
• idea that T helper cells are destroyed when HIV leaves the cell [1]

Question 30

Give one reason why people are short-sighted. [1]

Answer 30

Any one from:
- the eye(ball) is too long (1)
- the cornea is too curved (1)
- lens is too thick / too curved (1)
- the {cornea / lens} refracts the light too much (1)
- {light rays focus / focal point is} in front of the retina (1)

Question 31

Explain why reducing the blood supply to the heart muscle cells can cause a heart attack [3]

Answer 31

• less oxygen [1]
• less aerobic respiration/ more anaerobic respiration [1]
• creation of lactic acid [1]
• low pH [1]
• denature enzymes [1]

Question 32

Explain how chemical defence mechanisms in the body reduce the chance of infection [3]

Answer 32

• lysozymes [1]
• in tears [1]
• hydrochloric acid [1]
• in stomach [1]
• destroy pathogens [1]