ANCHOR B.2 (Genetics)

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.

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.

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 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.

A trait in cows is determined by two alleles of a single gene: allele R is dominant, and allele r is recessive. What is the probability of the dominant trait being expressed in the offspring of one RR parent and one rr parent?

• 25%

• 50%

• 75%

• 100%

Answer explanation

Based on a dominant-recessive inheritance pattern, a cross between a homozygous dominant (RR) parent and a homozygous recessive (rr) parent would predict a result of 100% of offspring exhibiting the dominant trait.

A genetic mutation involving a single base causes an error that affects the sequence of the next 500 amino acids in a protein. Which type of mutation could have produced this type of error in the protein?

• silent

• nonsense

• frame-shift

• substitution

Answer explanation

A frame-shift mutation may involve the insertion or deletion of a single base, can shift the reading frame of the gene, and can produce many subsequent changes in amino acids.

Which labels correctly complete the diagram?

• Y is replication, and Z is translation.

• Y is translation, and Z is replication.

• Y is transcription, and Z is translation.

• Y is translation, and Z is transcription.

Answer explanation

Process Y is transcription, and process Z is translation.

A male pistol shrimp with protective eye tissue pockets mates with a female shrimp without protective eye tissue pockets. All of the offspring have eye tissue pockets. Which statement is the most likely conclusion that can be made about the eye tissue pocket trait in pistol shrimp?

• It is a recessive, autosomal trait.

• It is a dominant, autosomal trait.

• It is a trait that results from multiple alleles.

• It is a trait that results from incomplete dominance.

Answer explanation

The eye tissue pocket trait is dominant and will result in offspring with at least one allele for the trait.

Examine the electrophoresis gel image. The victim of this crime wounded the suspect, whose blood stained the victim's clothing. Which suspect is the source of the DNA?

• Jenny

• Bob

• Mike

• Lisa

A man with hemophilia and a woman who has no history of the disease in her family plan to have a child. What best describes the outcome of their children?

• Any male child will have hemophilia, any daughter would be normal

• Any male child will have hemophilia, any daughter would be a carrier

• Any male child will be normal, any daughter would be normal

• Any male child will be normal, any daughter would be a carrier