Biology exam questions flashcards - cells and immunity

Question 1

Describe how HIV is replicated

Answer 1

• attachment proteins attach to receptors on helper t cell
• RNA enters the cell
• reverse transcriptase converts RNA to DNA
• viral protein/ capsid/enzyme produced
• virus particles assembled and released from cell

Question 2

What formula connects mass, concentration and volume ?

Answer 2

mass = concentration x volume
mass - g
concentration - gdm-3
volume - dm3

Question 3

Suggest and explain two further investigations that should be done before
this ADC is tested on human breast cancer patients.

( after it has been already tested on mice which have had human breast cancer tissue implanted under their skin)

*2 marks

Answer 3

• should be tested on other mammals to check for safety/ side effects
• tested on healthy humans to check for safety/ side effects
• investigate different concentrations of ADC to find suitable dosage

( max two of these points required)

Question 4

What are viral proteins ?

Answer 4

proteins incorporated within a virus such as capsid, enzymes, RNA etc

Question 5

Describe how the human immunodeficiency virus (HIV) is replicated once
inside helper T cells (TH cells).

Answer 5

• RNA is converted into DNA using reverse transcriptase
• DNA incorporated into nucleus of helper t cell
• DNA of HIV is transcribed into mRNA
  -HIV mRNA translated into viral proteins for
  assembly into viral particles

Question 6

Describe how a phagocyte destroys a pathogen present in the blood.

Answer 6

phagocyte engulfs pathogen into phagosome vesicle. lysosoyme fuses with phagosome and hydrolytic enzymes ( lysosymes) are released to hydrolyse pathogen

Question 7

Give two types of cell, other than pathogens, that can stimulate an immune
response.

Answer 7

• cancer cells
• antigen-presenting cells
• cells from other organisms of the same species

(why - they have foreign antigens on their surface)

Question 8

What is the role of the disulfide bridge in forming the quaternary structure
of an antibody?

Answer 8

joins two polypeptide chains

Question 9

Explain how HIV affects the production of antibodies when AIDS develops
in a person.

Answer 9

• less antibodies produced
• this is because HIV destroys helper t cells
• so fewer b cells clone and undergo differentiation to form plasma cells ( which produce antibodies)