A-LEVEL BIOLOGY Name:
Practice Paper 3 Maximum marks: 78 Time Allowed: 2 hours
These questions are from past papers covering topics and skills based on the advance
information to help you prepare for the exams this summer.
Answer all questions in the spaces provided.
Section B will require lined paper
Section A
1 (a) What name is used for the non-coding sections of a gene?
_____________________________________________________________
(1)
Figure 1 shows a DNA base sequence. It also shows the effect of two mutations on
this base sequence. Figure 2 shows DNA triplets that code for different amino acids.
Figure 1
Original DNA base sequence A T T G G C G T G T C T
Amino acid sequence
Mutation 1 DNA base sequence A T T G G A G T G T C T
Mutation 2 DNA base sequence A T T G G C C T G T C T
Figure 2
DNA triplets Amino acid
GGT, GGC, GGA, GGG Gly
GTT, GTA, GTG, GTC Val
ATC, ATT, ATA Ile
TCC, TCT, TCA, TCG Ser
CTC, CTT, CTA, CTG Leu
(b) Complete Figure 1 to show the sequence of amino acids coded for by the
original DNA base sequence.
(1)
Page 1
This document is licensed to Haggerston School - MB260045
, (c) Some gene mutations affect the amino acid sequence. Some mutations do not.
Use the information from Figure 1 and Figure 2 to explain
(i) whether mutation 1 affects the amino acid sequence
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
(2)
(ii) how mutation 2 could lead to the formation of a non-functional enzyme.
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
(3)
(d) Gene mutations occur spontaneously.
(i) During which part of the cell cycle are gene mutations most likely to occur?
__________________________________________________________
(1)
(ii) Suggest an explanation for your answer.
__________________________________________________________
__________________________________________________________
(1)
(Total 9 marks)
2 A student investigated the stages of mitosis in a garlic root. The root tip was placed on
a microscope slide with a stain. A cover slip was placed on top and the root tip was
firmly squashed.
(a) Explain why
(i) a root tip was used;
__________________________________________________________
__________________________________________________________
(1)
(ii) a stain was used;
__________________________________________________________
__________________________________________________________
(1)
Page 2
This document is licensed to Haggerston School - MB260045
Practice Paper 3 Maximum marks: 78 Time Allowed: 2 hours
These questions are from past papers covering topics and skills based on the advance
information to help you prepare for the exams this summer.
Answer all questions in the spaces provided.
Section B will require lined paper
Section A
1 (a) What name is used for the non-coding sections of a gene?
_____________________________________________________________
(1)
Figure 1 shows a DNA base sequence. It also shows the effect of two mutations on
this base sequence. Figure 2 shows DNA triplets that code for different amino acids.
Figure 1
Original DNA base sequence A T T G G C G T G T C T
Amino acid sequence
Mutation 1 DNA base sequence A T T G G A G T G T C T
Mutation 2 DNA base sequence A T T G G C C T G T C T
Figure 2
DNA triplets Amino acid
GGT, GGC, GGA, GGG Gly
GTT, GTA, GTG, GTC Val
ATC, ATT, ATA Ile
TCC, TCT, TCA, TCG Ser
CTC, CTT, CTA, CTG Leu
(b) Complete Figure 1 to show the sequence of amino acids coded for by the
original DNA base sequence.
(1)
Page 1
This document is licensed to Haggerston School - MB260045
, (c) Some gene mutations affect the amino acid sequence. Some mutations do not.
Use the information from Figure 1 and Figure 2 to explain
(i) whether mutation 1 affects the amino acid sequence
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
(2)
(ii) how mutation 2 could lead to the formation of a non-functional enzyme.
__________________________________________________________
__________________________________________________________
__________________________________________________________
__________________________________________________________
(3)
(d) Gene mutations occur spontaneously.
(i) During which part of the cell cycle are gene mutations most likely to occur?
__________________________________________________________
(1)
(ii) Suggest an explanation for your answer.
__________________________________________________________
__________________________________________________________
(1)
(Total 9 marks)
2 A student investigated the stages of mitosis in a garlic root. The root tip was placed on
a microscope slide with a stain. A cover slip was placed on top and the root tip was
firmly squashed.
(a) Explain why
(i) a root tip was used;
__________________________________________________________
__________________________________________________________
(1)
(ii) a stain was used;
__________________________________________________________
__________________________________________________________
(1)
Page 2
This document is licensed to Haggerston School - MB260045
