Past Paper Questions

Question 1

Give 3 structural features found in all virus particles

Answer 1

Genetic material
Capsid
Attachment protein

Question 2

What is the function of genetic material in viruses

Answer 2

Codes for viral proteins

Question 3

What is the function of capsids in viruses

Answer 3

Protects the genetic material

Question 4

What is the function of attachment proteins in viruses

Answer 4

Binds to receptors on the host cell

Question 5

Explain why viruses are described as acellular and non living

Answer 5

Acellular because they aren’t made of cells

Non living because they can’t independently replicate

Question 6

Explain why antibiotics are not effective against viruses

Answer 6

1)Antibiotics kill bacteria by targeting bacteria specific enzymes or organelles. They are ineffective against viruses due to the virus using the host’s machinery to replicate, as viruses are acellular.

2)Some antibiotics work by destroying the links in the peptidoglycan cell walls of bacteria, making them more susceptible to osmosis lysis, hence killing them. Antibiotics therefore can’t destroy the viruses as they don’t have a peptidoglycan cell wall, only a capsid

3) some antibiotics also inhibit DNA replication, if a virus is a retro virus such as HIV, there is no DNA to replicate (as HIV has RNA as it’s genetic information)

Question 7

Give 3 functions of the golgi apparatus in a eukaryotic cell

Answer 7

Modifies/packages/transports proteins

Modifies/packages/transports lipids

Forms vesicles and lysosomes

Question 8

In Africa today, most of the human population are resistant to malaria.
Use your knowledge of natural selection to explain why this resistance is so common in Africa

Answer 8

Random mutation produces an allele.

Those with the allele are resistant to malaria so don’t get malaria, or survive it

These people are therefore more likely to reproduce and pass on the allele

Over generations, the allele frequency increases

Question 9

Give another name for a phagocyte

Answer 9

Macrophage

Question 10

Explain the movement of oxygen into the gas exchange system of an insect when it is at rest (3 marks)

Answer 10

• Oxygen is used in aerobic respiration,
• So an oxygen concentration is established,
• This causes oxygen to diffuse in through the spiracles, with the concentration gradient.

Question 11

Explain how an anthsma attach causes a decrease in airflow (3)

Answer 11

During an anthsma attack:
- The muscle walls in the bronchi contract,
- The walls of the bronchi secrete more mucus,
- The diameter of the airways is reduced,
Therefore, all of these factors reduce airflow