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IB Biology D2.2: Gene Exp. — Practice Questions & Answers
IB Biology D2.2 HL study notes: how genes are switched on and off, transcription factors, epigenetics, methylation and the environment.
Here are 10 practice questions with full answers and explanations.
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Practice questions with answers
1
Multiple choice
What is gene expression?
I. The process by which the information encoded in a gene is used to synthesize a functional gene product
II. The creation of a protein or a functional RNA molecule (such as tRNA or rRNA) from the instructions in a gene
III. Translation of single stranded DNA to a polypeptide
IV. The process of copying an entire DNA molecule to create identical sister chromatids before cell division
I and II only
I, II, and III only
I and III only
II, III and IV only
All I, II, III and IV
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Why Gene expression involves transcription of DNA to RNA and translation of RNA to protein.
2
Multiple choice
What regulates transcription by binding to specific DNA base sequences?
Proteins.
Lipids.
Carbohydrates.
Minerals.
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Why Regulatory proteins called transcription factors bind specific DNA sequences to control transcription.
3
Multiple choice
What are examples of DNA sequences that regulate transcription?
I. Promoters
II. Enhancers
III. Transcription factors
IV. Telomeres
V. Introns
VI. Exons
I, II, and III only
I and II only
I and III only
II, III and IV only
All I, II, III, IV, V and VI
I and IV only
V and VI only
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Why Promoters, enhancers, and operators are DNA sequences that regulate transcription of genes.
4
Multiple choice
How is translation regulated?
Control of mRNA degradation.
Control of DNA replication.
Control of protein folding.
Control of lipid synthesis.
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Why Translation is regulated partly by controlling how quickly mRNA is degraded.
5
Multiple choice
What breaks down mRNA in human cells?
Nucleases.
Proteases.
Lipases.
Amylases.
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Why Nucleases are enzymes that break down mRNA, controlling how long it remains available.
6
Multiple choice
What is epigenesis?
The development of differentiation patterns in multicellular organisms
The process of DNA replication
The process of protein synthesis
A process that changes the DNA sequence
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Why Epigenesis is the development of differentiation patterns as a multicellular organism develops.
7
Multiple choice
What is altered by epigenetic changes?
Phenotype.
Genotype.
DNA base sequences.
Chromosome number.
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Why Epigenetic changes alter phenotype by changing gene expression without changing the DNA sequence.
8
Multiple choice
What determines how a cell differentiates?
The pattern of gene expression.
The rate of DNA replication.
The rate of protein synthesis.
The rate of cellular respiration.
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Why A cell differentiates according to its particular pattern of gene expression.
9
Multiple choice
What are examples of epigenetic tags?
Methylation of the promoter and histones.
Phosphorylation of glucose.
Hydrolysis of ATP.
Oxidation of NADH.
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Why Epigenetic tags include methylation of promoter DNA and chemical modification of histones.
10
Multiple choice
What does methylation of cytosine in a promoter do?
Represses transcription.
Activates transcription.
Increases translation.
Decreases translation.
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Why Methylation of cytosine in a promoter represses transcription of the associated gene.
Key terms in Gene Exp.
Gene expression: The process by which the information in a gene is used to make a product, typically a protein; controlled so that only some genes are active in a given cell.
Transcription factor: A protein that binds to a specific DNA sequence and increases (activator) or decreases (repressor) the transcription of a gene.
Promoter: The region of DNA near the start of a gene where RNA polymerase and transcription factors bind to begin transcription.
Epigenetics: Changes in gene expression that do not involve a change to the DNA base sequence and can be passed to daughter cells.
DNA methylation: The addition of methyl groups, usually to cytosine in a promoter, which generally silences a gene.
Histone: A protein around which DNA is wound; chemical modification of histones loosens or tightens DNA packaging and so affects expression.
Epigenome: The complete set of epigenetic chemical tags on a cell’s DNA and histones, which can be inherited by daughter cells.
Differentiation: The process by which a cell becomes specialised by expressing a characteristic subset of its genes.
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