Question 1

What is an operon?

  A  

the binding site for a repressor protein


  B  

any group of genes responsible for the metabolism of lactose in prokaryotes or eukaryotes

  C  

a cluster of genes under the control of a promoter

  D  

a regulatory gene

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Question 2

How do transcription factors affect the transcription of a gene when they bind to its promoter region?

  A  

they always initiate transcription

  B  

they always prevent transcription

  C  

they have no effect on transcription

  D  

they can either enhance or inhibit transcription

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Question 3

To what do transcription factors in eukaryotes bind?

  A  

operons

  B  

specific DNA sequences near genes

  C  

mRNA

  D  

ribosomes

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Question 4

What is the function of the product of the regulatory gene in the lac operon?

  A  

it breaks down lactose

  B  

it speeds up the transcription process

  C  

it suppresses the transcription of structural genes

  D  

it transports lactose into the cell

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Question 5

Which molecule affects the binding of the lac repressor to the operator site?

  A  

glucose

  B  

galactose

  C  

sucrose

  D  

lactose

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Question 6

What is the role of the regulatory gene in the lac operon?

  A  

it codes for β-galactosidase

  B  

it codes for the lac repressor protein

  C  

it allows lactose to enter the cell

  D  

it breaks down lactose into glucose

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Question 7

The enzyme β-galactosidase is classified as what type of enzyme?

  A  

inducible enzyme

  B  

repressible enzyme

  C  

constitutive enzyme

  D  

permanent enzyme

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Question 8

What happens when lactose is present in the medium where a bacterium capable of digesting lactose is growing?

  A  

lactose is ignored by the bacterium

  B  

lactose prevents transcription of the lac operon

  C  

lactose is broken down outside the bacterial cell

  D  

lactose induces transcription of the lac operon

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Question 9

Which gene in the lac operon codes for an enzyme that allows lactose to enter the bacterial cell?

  A  

lacZ

  B  

lacY

  C  

lacA

  D  

lacI

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Question 10

How does gibberellin affect plant growth?

  A  

by binding to DELLA proteins

  B  

by breaking down DELLA proteins

  C  

by causing the breakdown of DELLA proteins

  D  

by synthesising DELLA proteins

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