Exam pack 4 - Mistakes FC

Question 1

What is the liquid in chloroplast

Answer 1

Stroma

Question 2

What are layers of lamellae called?

Answer 2

Granum

Question 3

What is a vaccination?

Answer 3

• an injection containing dead or weakened forms of a pathogen’s antigens
• Resulting in the formation of memory cells

Question 4

Describe how HIV is replicated after it enters the human cell

Answer 4

1. It’s viral RNA is translated and transcribed to form DNA by reverse transcriptase
2. The DNA I produced is used to produce viral proteins @ ribosome
3. DNA joins to host cell’s DNA
4. These viral proteins associate with each other to form viral particles.
5. These viral particles bud off the host cell’s membrane

Question 5

The destruction of T - cells by HIv leads to the death of an infected person. Explain how

Answer 5

1. No B lymphocytes are stimulated to divide by mitosis, to produce B plasma cells
2. So no production of antibodies with receptors complementary to specific antigen found on the HIV
3. Person is now more prone to infection.

Question 6

Lactose is a disaccharide and in the small intestine, it is digested into glucose and galactose. What evidence suggests that galactose is a monosaccharide?

Answer 6

Digestion of a disaccharide produces monosaccharides

Question 7

Suggest one advantage of the different percentage of cholesterol in red blood cells compared to cells found in the lining of the ileum.

Answer 7

RBC are free in blood, and are not supported by other cells.
So cholesterol helps to maintain its shape.

Question 8

How is a bacterial cell able to maintain a constant shape?

Answer 8

It’s cell walls is made of murein
So cell is unable to change shape

Question 9

Explain how the organic bases help to stabilise the structure of DNA

Answer 9

Complementary base pairing allows the strands to be held together

And many hydrogen bonds provides strength

Question 10

Suggest one advantage of showing the genetic code as base sequences on mRNA rather than triplet codes on DNA

Answer 10

DNA has 2 strands, with diff complementary base sequences

Question 11

What is the function of stop codon

Answer 11

Stop translation

This results in detachment of polypeptide from ribosome

Question 12

A starting point for a question that asks for the impact of decrease in pH on enzyme activity

Answer 12

Descrease in pH increase the number of H+ ions attracted to amino acids.

Question 13

The student was advised that they could improve their graph by taking additional readings, explain how

Answer 13

1. Line of best fit will be more accurate
2. Point where line crosses x axis will be more accurate