CGP exam style questions on DNA

Question 1

What are chromosomes? (1)

Answer 1

The structures that contain DNA

Question 2

Outline the function of genes (1)

P.S

Answer 2

code for particular sequences of amino acids

Question 3

What is meant by the term genome (1)
SET
of an

Answer 3

the entire SET of an organism’s genetic material

Question 4

Give one reason why it is important for scientists to have an understanding of the human genome (2)
it allows scientists to IDENTIFY GENES
linked to…
tret

Answer 4

it allows scientists to IDENTIFY GENES that are linked to (particular) inherited diseases
knowing which genes are linked to these inherited diseases can help us to develop effective treatments for them

Question 5

Explain how the DNA bases in a gene code for a specific chain of amino acids (2)
B
A

Answer 5

Each sequence of 3 bases, code for 1 specific amino acid (1)
so the ORDER of the bases in the gene
decides the ORDER of the amino acids in the chain

Question 6

Name the structures in a cell where protein synthesis takes place

Answer 6

ribosomes

Question 7

Describe the role of non-coding DNA

EX

Answer 7

switches genes on and off

determine which genes are expressed

Question 8

Explain how DNA can be used in the synthesis of proteins when it is unable to leave the nucleus.
1st Stage
PROTEIN SYNTHESIS

Answer 8

CODE FROM THE DNA is copied which produces a molecule called mRNA (1 mark)
(The mRNA leaves the nucleus (to the cytoplasm) and onto the ribosomes)
The mRNA carries the code from the DNA to the site of protein synthesis (1 mark)

Question 9

Explain what happens to a chain of amino acids once it has been assembled
3rd stage
PROTEIN SYNTHESI S

Answer 9

It folds up to a unique shape (1 mark) which allows the protein to perform the task that it is meant to (1 mark)

Question 10

Proteins have many different jobs. Outline the role of two proteins that are found in the human body.

Answer 10

collagen –> formS structures in the body

e.g. hormones( 1 mark) these are used to carry messages around the body
e.g. enzymes ( 1 mark)
these act as a biological catalysts to speed up chemical reactions in the body

Question 11

Suggest one possible effect of a mutation that changes the shape of a structural protein
SSSSSSSSSS

Answer 11

the mutation could cause the structural protein to LOSE its STRENGTH(1 mark)
meaning that it may no longer be able to carry out its job of providing STRUCTURE and SUPPORT ( 1 mark)

Question 12

Suggest one possible effect of a mutation in a gene that codes for a particular enzyme

Answer 12

the shape of the enzyme’s active site could be changed ( 1 mark)
meaning that its substrate may no longer be able to bind to it ( 1 mark)
so the enzyme is no longer able to catalyse the reaction ( 1 mark)

Question 13

Describe the process that takes place at the site of protein synthesis to produce chains of amino acids.
PROTEIN SYNTHESIS
2nd stage

Answer 13

Carrier molecules (tRNA)
(1 mark) bring the amino acids and line them up (in the right order) along their corresponding triplet code. 
amino acids join together to form a protein