Biology STAAR Review - Reporting Category 2

Which of these shows an example of an insertion mutation?

• A

• B

• C

• D

Answer explanation

An insertion mutation is a result of inserting new nitrogenous bases into DNA. In this model, new “K” and “L” genes have been inserted into the chromosome.

A model of the genetic control of coat color in rabbits is shown.

Which Punnett square represents a cross that would produce albino offspring?

• 
• 
• 
• 

Answer explanation

The albino allele (c) is recessive to all other alleles, so expression of the albino phenotype requires two copies of the allele. This option is the only option where two albino alleles would result.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

A model of transcription and a codon chart are shown.

Which amino acid would be coded first from the DNA strand being transcribed?

• Cys

• Phe

• Ile

• Met

Answer explanation

The first mRNA codon is AUG. AUG on the codon chart codes for the amino acid Met.

Tags

NGSS.HS-LS1-1

A cellular process is shown.

Which of these is the most likely result of the process shown in the diagram?

• Chromosome replication will cease to avoid errors that result in mutations.

• Offspring will no longer express traits from previous generations.

• Gametes will contain new allele combinations.

• Chromatids will have less genetic variety.

Answer explanation

In meiosis, during the cellular process of crossing over, homologous chromosome pairs exchange parts with each other creating new allele combinations on each chromosome.

Tags

NGSS.HS-LS3-2

What components make up the backbone of a DNA molecule?

• Purines and deoxyribose

• Pyrimidines and purines

• Deoxyribose and phosphate groups

• Phosphate groups and pyrimidines

Answer explanation

The backbone of a DNA molecule is made up of alternating deoxyribose sugars and phosphates.

Which statement best describes a similarity among trees, cats, and amoebas?

• They are prokaryotic organisms.

• They are classified as members of the same kingdom.

• They have genomes that consist of the same number of genes.

• They contain DNA composed of the same four types of nucleotides.

Answer explanation

All organisms are composed of the same nucleotide bases.

Tags

NGSS.MS-LS4-2

A model of DNA is shown.

Which part of the DNA model is most directly associated with the coding of genetic information?

• 
• 
• 
• 

Answer explanation

The variability in nitrogenous bases carries the genetic information that encodes for traits.

Tags

NGSS.HS-LS1-1

In domesticated dogs, hair type is controlled by two different alleles. The allele for wire hair is (H) and the allele for smooth hair is (h).

When two heterozygous dogs are crossed, what percentage of the offspring is expected to be homozygous for smooth hair?

• 0%

• 25%

• 50%

• 75%

Answer explanation

When two heterozygous dogs are crossed, the percentage of the offspring that are expected to be homozygous for smooth hair will be 25%. In a Punnett square, Hh × Hh will result in 25% HH (homozygous wirehair), 50% Hh (heterozygous wirehair), and 25% hh (smooth hair).

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

Which statements explain how a mutation in a somatic cell is different from a mutation that occurs in gametes?

• Somatic cell mutations occur in cells that give rise to gametes. Gamete mutations occur in cells that result in apoptosis.

• Somatic cell mutations are maintained in the gene pool. Gamete mutations are expelled from the gene pool.

• Somatic cell mutations are generally not passed to offspring. Gamete mutations are usually passed to offspring.

• Somatic cell mutations will not be expressed by the individual that contains the mutation. Gamete mutations will be expressed by the individual.

Answer explanation

Somatic cell mutations occur in body cells affecting a single cell or tissue. They are not inherited/passed on to offspring. Gamete mutations occur in sperm or egg cells. Gamete mutations can be inherited/passed on to offspring.

Tags

NGSS.HS-LS3-2

E. coli has three genes that each code for different enzymes that break down lactose. Scientists conducted investigations about the production of these enzymes using samples of E. coli. Their results are shown in the table.

Which conclusion about the production of the enzymes can be determined by analyzing the scientists’ results?

• Gene expression for the enzymes was controlled by the temperature of lactose.

• The genes for the enzymes were expressed in equal amounts during both experiments.

•  Gene expression for the enzymes was controlled by the presence of lactose.

• The genes for the enzymes were mutated before being expressed by the presence of lactose.

Answer explanation

The scientists’ results indicate that gene expression for the enzymes was controlled by the presence of lactose because enzyme concentration was high when lactose was present and low when lactose was not present.