5.2.23 - Topic 6 - Genetics - Biology Keystone Review

Which statement best explains how organisms accomplish passing on traits to their offspring?

• Traits are acquired when parents care for their offspring.

• Offspring inherit traits when DNA is replicated during mitosis.

• Traits are inherited by the transfer of genetic material from parent to offspring.

• Offspring acquire traits when cells become specialized for certain functions.

Answer explanation

DNA is the genetic material transferred from parent to offspring, and it codes for an organism’s inherited traits.

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Which statement best describes how organisms use DNA and amino acids to synthesize a protein?

• DNA is transcribed into mRNA, which is translated by the ribosome to produce an amino acid chain.

• DNA is translated into mRNA, which is transcribed by the ribosome to produce an

  amino acid chain.

• Amino acids are transcribed into mRNA, which is translated in the nucleus to produce a

  molecule of DNA.

• Amino acids are translated into mRNA, which is transcribed in the nucleus to produce a

  molecule of DNA.

Answer explanation

The two key stages of protein synthesis are described.

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The DNA Replication diagram is incomplete. Which nucleotide sequence accurately shows the DNA strand that would be produced during DNA replication?

• TCCA

• AGGT

• UCCU

• AGGU

Answer explanation

A pairs with T, G pairs with C twice, and T pairs with A.

Which statement describes how cloning is different from selective breeding?

• Cloning eliminates recessive alleles from a genome.

• Cloning transforms harmful traits into beneficial traits.

• Cloning corrects or replaces mutated gene sequences.

• Cloning results in offspring genetically identical to the parents.

Answer explanation

Cloning results in exact copies of genetic material, including

offspring that are identical to their parents.

A scientist wants to make a change to a genetic code that will lead to the removal of one amino acid from the sequence of a protein. Which genetic material should the scientist remove?

• three genes

• three alleles

• three nucleotides

• three chromosomes

Answer explanation

Removing three nucleotides would remove one amino acid

because a single amino acid is determined by a codon, and a

codon is three adjacent nucleotides.

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Which sequence of events correctly describes the process of protein synthesis?

• A

• B

• C

• D

Answer explanation

The process of protein synthesis includes DNA being

transcribed into mRNA, which is translated into proteins.

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A scientist observes that a certain trait is determined by a single allele. An organism

inherited one version of the trait from one parent and another version from the other

parent. Both versions of the trait are expressed in the phenotype of the offspring. Which

pattern of inheritance best classifi es the observed trait?

• dominance

• sex-linkage

• co-dominance

• incomplete dominance

Answer explanation

The patt ern of inheritance is best described as co-dominance because both traits are fully expressed in the phenotype of the individual.

The bacterium Acetobacter aceti is found in acidic environments and has an acidic

cytoplasm. For this reason, most of its proteins are able to function in acidic conditions.

This property distinguishes Acetobacter aceti proteins from those of most other

organisms. Which characteristic does Acetobacter aceti most likely share with other

organisms?

• the method that the organism uses to reproduce itself

• the physical and chemical responses to environmental changes

• the type of organelle used to produce energy for cellular functions

• the process used to form proteins by transcription and translation

Answer explanation

Prokaryotes and eukaryotes both have ribosomes that synthesize proteins

A mutation occurs at the midpoint of a gene, altering all amino acids encoded after the point of mutation. Which mutation could have produced this change?

• deletion of two nucleotides

• deletion of three nucleotides

• insertion of six nucleotides

• insertion of twelve nucleotides

Answer explanation

A deleti on of two nucleoti des will most likely cause a shift in the codon sequence that codes for an amino acid. This could cause a change in the sequence of amino acids att ached aft er the point of the

mutati on.

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Which statement best describes the relationship between an allele and a gene?

• An allele is a variation of a gene that can be expressed as a phenotype.

• An allele is the part of a gene that attaches to messenger RNA molecules.

• An allele is a segment of a DNA molecule that controls replication of a gene.

• An allele is the primary protein made by a gene found in a developing embryo.

Answer explanation

An allele is any form of a particular gene, located at a

specific position on a chromosome, which can be expressed as a phenotype.

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