1.
State what is meant by totipotent cells.
[1 mark]
- can become any body cell including placenta
JD SCIENCE
The control of gene expression
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by pluripotent cells.
[1 mark]
- can become any body cell except placenta
3.
State what is meant by transcription factors.
[1 mark]
- proteins that bind DNA and switch genes on or off
4.
State what is meant by epigenetics.
[1 mark]
- heritable changes in gene function without changing the base sequence
5.
State what is meant by RNA interference.
[1 mark]
- siRNA / miRNA can stop mRNA being translated
6.
State what is meant by a tumour suppressor gene.
[1 mark]
- slows the cell cycle / promotes apoptosis
7.
State what is meant by a proto-oncogene.
[1 mark]
- stimulates the cell cycle
8.
State what is meant by recombinant DNA.
[1 mark]
- DNA from more than one source
9.
State what is meant by PCR.
[1 mark]
- amplifies DNA
10.
State what is meant by gel electrophoresis.
[1 mark]
- separates DNA fragments by size
11.
Amira is asked about totipotent cells in a AQA Biology paper.
(a) [2 marks]
- zygote
(b) [3 marks]
- genes not yet permanently switched off
12.
Amira is asked about pluripotent cells in a AQA Biology paper.
(a) [2 marks]
- embryonic stem cells
(b) [3 marks]
- used in research
13.
Amira is asked about transcription factors in a AQA Biology paper.
(a) [2 marks]
- oestrogen can be a stimulus
(b) [3 marks]
- needed for cell specialisation
14.
Amira is asked about epigenetics in a AQA Biology paper.
(a) [2 marks]
- methylation, acetylation
(b) [3 marks]
- environment can affect this
15.
Amira is asked about RNA interference in a AQA Biology paper.
(a) [2 marks]
- breaks down mRNA
(b) [3 marks]
- gene silencing
16.
Amira is asked about a tumour suppressor gene in a AQA Biology paper.
(a) [2 marks]
- if mutated, cell cycle runs on
(b) [3 marks]
- both copies often need to fail
17.
PCR: starting with 1 molecule, copies after 5 cycles
[3 marks]
- Final answer: 32
18.
A fragment is 600 bp. After a 6-cutter idea, number of fragments depends on sites — if 2 cut sites on a linear DNA
[3 marks]
- Final answer: 3 fragments
19.
Stem cell therapy risk: name one
[3 marks]
- Final answer: tumour formation / rejection
20.
Methylation of a promoter typically
[3 marks]
- Final answer: reduces transcription
21.
A gene is 900 bases coding. Amino acids (no stop)
[3 marks]
- Final answer: 300
22.
Dilution 1 in 10 four times. Final dilution
[3 marks]
- Final answer: 1 in 10 000
23.
Amira carries out a AQA-style required practical linked to control of gene expression. This is a typical AQA required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Amira carries out collecting valid data for control of gene expression. This is a typical AQA required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Amira carries out drawing a graph for control of gene expression. This is a typical AQA required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Amira carries out evaluating a method about control of gene expression. This is a typical AQA required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare totipotent cells with pluripotent cells.
[4 marks]
- can become any body cell including placenta
- can become any body cell except placenta
- give one linked difference
28.
Compare pluripotent cells with transcription factors.
[4 marks]
- can become any body cell except placenta
- proteins that bind DNA and switch genes on or off
- give one linked difference
29.
Compare transcription factors with epigenetics.
[4 marks]
- proteins that bind DNA and switch genes on or off
- heritable changes in gene function without changing the base sequence
- give one linked difference
30.
Compare epigenetics with RNA interference.
[4 marks]
- heritable changes in gene function without changing the base sequence
- siRNA / miRNA can stop mRNA being translated
- give one linked difference
31.
Apply your knowledge of a proto-oncogene to this situation: becomes an oncogene if mutated
[3 marks]
- becomes an oncogene if mutated
32.
Apply your knowledge of recombinant DNA to this situation: restriction enzymes, ligase, vectors
[3 marks]
- restriction enzymes, ligase, vectors