STAAR Biology Reporting Category

Green anoles are lizards that can change their skin color rapidly in response to various stimuli. This adaptation is the result of -

• selective breeding of lizards by humans

• beneficial traits passed from parents to offspring

• geographic isolation that prevented genetic mutation

• environmental pollutants that changed their genotype

Answer explanation

Adaptations (like the ability to change skin color to hide from predators) are beneficial traits that are passed down from parent to offspring that help organisms survive and reproduce.

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Why is it important to assign each organism a scientific name?

• Each scientific name applies to only one species, making it universally identifiable to scientists.

• Each scientific name allows scientists to better study the behavior of an organism.

• The scientific name allows scientists to develop common names for organisms.

• The scientific name describes how an individual looks relative to others of the same genus.

Answer explanation

Each scientific name applies to one species, making it universally identifiable to scientists across languages and regions. Additionally, scientific names help scientists avoid confusion when multiple common names may be used to describe a single species.

Two scientists studied patters of evolution in the fossil record. Many species they analyzed showed period of slow changes interrupted by a period of rapid change.

This pattern of periods of slow change interrupted by periods of rapid change with few, if any transitional fossils, best describes the theory of ---

• natural selection

• genetic drift

• punctuated equilibrium

• gene flow

Answer explanation

The theory of punctuated equilibrium, devised by Niles Eldredge and Stephen Jay Gould, is characterized by periods of slow change interrupted by periods of rapid change with few transitional fossils in the fossil record.

Which of these best explains how the viceroy butterfly benefits from looking like the monarch butterfly?

• Viceroy butterflies are able to reproduce with the monarch butterflies.

• Viceroy butterflies are able to deter predators in the same way as the monarch butterflies.

• Viceroy butterflies are able to follow the migratory patterns of the monarch butterflies.

• Viceroy butterflies are able to find additional sources of food used by the monarch butterflies.

Answer explanation

The viceroy butterfly benefits from mimicking the monarch butterfly by being able to deter predators who avoid eating monarch butterflies due to their bad taste.

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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.

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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.

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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.

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A model of DNA is shown.

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

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Answer explanation

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

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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.

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

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

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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.

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