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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 the role of transcription factors in the nucleus?
To catalyze the splicing of mRNA molecules before translation
To transport tRNA molecules from the cytoplasm to the ribosome during protein synthesis
To synthesize ribosomal RNA for ribosome assembly
Regulate gene expression
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Why Transcription factors bind DNA to switch specific genes on or off, regulating gene expression.
2
Multiple choice
What is gene expression?
I and III only
I, II, and III only
II. The creation of a protein or a functional RNA molecule (such as tRNA or rRNA) from the instructions in a gene
IV. The process of copying an entire DNA molecule to create identical sister chromatids before cell division
II, III and IV only
I and II only
All I, II, III and IV
I. The process by which the information encoded in a gene is used to synthesize a functional gene product
III. Translation of single stranded DNA to a polypeptide
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Why Gene expression involves transcription of DNA to RNA and translation of RNA to protein.
3
Multiple choice
What regulates transcription by binding to specific DNA base sequences?
Carbohydrates.
Lipids.
Minerals.
Proteins.
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Why Regulatory proteins called transcription factors bind specific DNA sequences to control transcription.
4
Multiple choice
What are examples of DNA sequences that regulate transcription?
II, III and IV only
VI. Exons
I and IV only
II. Enhancers
IV. Telomeres
I and II only
All I, II, III, IV, V and VI
V and VI only
V. Introns
I and III only
I, II, and III only
I. Promoters
III. Transcription factors
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Why Promoters, enhancers, and operators are DNA sequences that regulate transcription of genes.
5
Multiple choice
How is translation regulated?
Control of lipid synthesis.
Control of protein folding.
Control of mRNA degradation.
Control of DNA replication.
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Why Translation is regulated partly by controlling how quickly mRNA is degraded.
6
Multiple choice
What breaks down mRNA in human cells?
Proteases.
Nucleases.
Amylases.
Lipases.
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Why Nucleases are enzymes that break down mRNA, controlling how long it remains available.
7
Multiple choice
What is epigenesis?
The process of protein synthesis
The process of DNA replication
A process that changes the DNA sequence
The development of differentiation patterns in multicellular organisms
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Why Epigenesis is the development of differentiation patterns as a multicellular organism develops.
8
Multiple choice
What is altered by epigenetic changes?
Phenotype.
DNA base sequences.
Genotype.
Chromosome number.
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Why Epigenetic changes alter phenotype by changing gene expression without changing the DNA sequence.
9
Multiple choice
What determines how a cell differentiates?
The rate of protein synthesis.
The pattern of gene expression.
The rate of DNA replication.
The rate of cellular respiration.
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Why A cell differentiates according to its particular pattern of gene expression.
10
Multiple choice
What are examples of epigenetic tags?
Hydrolysis of ATP.
Oxidation of NADH.
Phosphorylation of glucose.
Methylation of the promoter and histones.
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Why Epigenetic tags include methylation of promoter DNA and chemical modification of histones.
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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