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Cambridge AS & A Level Biology 9700 — Revision Notes

1 · Cell Structure

0/26

2 · Biological Molecules

0/51

3 · Enzymes

0/29

4 · Cell Membranes and Transport

0/41

5 · The Mitotic Cell Cycle

0/21

6 · Nucleic Acids and Protein Synthesis

0/22

7 · Transport in Plants

0/28

8 · Transport in Mammals

0/39

9 · Gas Exchange

0/13

10-11 · Infectious Disease and Immunity

0/43

12 · Energy and Respiration

0/37

13 · Photosynthesis

0/23

14-15 · Homeostasis and Control

0/57

16 · Inherited Change

0/33

17-18 · Selection, Evolution, Classification and Conservation

0/70

19 · Genetic Technology

0/44
Quiz

16.3.2 Gene Control- Lac Operon – Exam questions

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  • Questions count: 15
  • Passing grade: B+
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1.

In the lac operon, when lactose is absent

the repressor binds to the operator and blocks transcription
RNA polymerase transcribes the genes
lactose binds the repressor
β-galactosidase is made
2.

The lac operon is found in

humans
yeast only
Escherichia coli
viruses
3.
According to the comparison table in this lesson, what is the lac operon of Genes code for?
According to the comparison table in this lesson, what is the lac operon of Genes code for?
lac vs trp operon
Lactose inactivates repressor → on
Lactose digestion enzymes
Off
Inducible
4.

In an inducible operon such as lac, the genes are transcribed when

the repressor binds the operator
the inducer inactivates the repressor
glucose is high only
no lactose is present
5.
In the lac operon, lactose acts as an
operator
promoter
inducer that inactivates the repressor
repressor
6.
Complete the statement: The lac operon is ______.
Complete the statement: The lac operon is ______.
trp operon
Operon
increases
inducible
7.
Which statement best describes lac operon?
Which statement best describes lac operon?
Protein blocking transcription.
Inducible; turned on by lactose.
Repressible; turned off by tryptophan.
Methylation and histone changes affecting expression.
8.
In the lac operon, what happens when lactose is present?
Lactose binds the repressor, which leaves the operator
The repressor binds more tightly
RNA polymerase is inhibited
The regulator gene is deleted
9.
In the lac operon, when lactose is absent,
the repressor binds the operator and blocks transcription
RNA polymerase transcribes the genes at maximum rate
the genes are translated but not transcribed
lactose binds the promoter
10.
Which key term matches this description: "Group of genes with one promoter (bacteria)."
Which key term matches this description: "Group of genes with one promoter (bacteria)."
Enhancer
Operon
Epigenetics
trp operon
11.

A structural gene codes for

a protein that controls another gene
rRNA only
no product
a protein with a function in the cell, such as an enzyme
12.

When lactose is present, it

binds to the promoter
binds to the repressor, changing its shape so that it cannot bind to the operator
destroys RNA polymerase
binds to the operator
13.

β-galactosidase is an example of

a repressible enzyme
an inducible enzyme
a structural protein
a hormone
14.

The advantage to a bacterium of controlling gene expression is that

all genes are always on
mutations are prevented
resources are not wasted making proteins that are not needed
DNA replication is faster
15.
Short sequence by the promoter that assists transcription by interacting with regulatory proteins.
Short sequence by the promoter that assists transcription by interacting with regulatory proteins.
Enhancer
Repressor
Operator
Promoter
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Part of 16 · Inherited Change — see every lesson and quiz in this unit.
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