STAAR Success - High School Biology - Practice #2
Read each question carefully. Choose the best answer to each question. For open-response questions, determine the best answer to the question.
Question 1a
In the context of epigenetics, which process involves the addition of methyl groups to DNA, often leading to gene silencing?
Histone acetylation
DNA methylation
RNA interference
Chromatin remodeling
Question 1b
Which of the following is a characteristic feature of prion diseases?
They are caused by misfolded proteins that induce normal proteins to misfold.
They result from viral infections that integrate into the host genome.
They are inherited through mitochondrial DNA mutations.
They involve autoimmune attacks on nervous tissue.
Question 1c
Which process is primarily responsible for the generation of antibody diversity in the human immune system?
Alternative splicing of mRNA
Somatic hypermutation
Gene duplication
Transposon insertion
Question 1d
Which of the following best describes the function of telomerase in eukaryotic cells?
It repairs mismatched DNA bases during replication.
It adds repetitive nucleotide sequences to the ends of chromosomes.
It unwinds the DNA helix ahead of the replication fork.
It synthesizes RNA primers for DNA polymerase.
Question 1e
Explain the role of chaperone proteins in cellular function. Provide an example of a situation where chaperone proteins are essential.
Group 2
Source: Digital Atlas of Ancient Life
Question 2a
Which two species share the most recent common ancestor according to the phylogenetic tree?
A and C
F and H
G and H
B and E
Question 2b
What does node 7 on the phylogenetic tree represent?
The most recent common ancestor of all species shown.
The divergence between species A and B.
A unique evolutionary trait shared only by species G and H.
A grouping of species with identical evolutionary histories.
Group 3
This question has two parts. First, answer Part A. Then, answer Part B.
Question 3a
Part A: Which of the following best explains the concept of genetic drift?
It is the change in allele frequencies due to random sampling effects in small populations.
It is the movement of alleles between populations through migration.
It is the increase in advantageous alleles due to natural selection.
It is the introduction of new alleles through mutation.
Question 3b
Part B: Which scenario is an example of the genetic drift described in Part A?
A natural disaster drastically reduces the size of a population, altering allele frequencies.
Individuals migrate between populations, introducing new alleles.
A beneficial mutation spreads through a population over time.
A population adapts to a new environment through selective pressures.
Question 4a
Which of the following is a characteristic feature of quorum sensing in bacterial populations?
It allows bacteria to sense and respond to population density.
It enables bacteria to evade the host immune system.
It involves the transfer of genetic material between bacteria.
It is a mechanism for antibiotic resistance.
Group 5
Source: CK-12 Foundation
Question 5a
What does the decreasing biomass at each level of this energy pyramid indicate about energy transfer in an ecosystem?
Energy is lost as heat at each trophic level.
Producers contain less energy than consumers.
Energy is gained as it moves up the trophic levels.
Energy is recycled entirely by the decomposers.
Question 5b
Explain why the phytoplankton, as primary producers, have the largest biomass in this energy pyramid and how this supports the ecosystem.
Question 6a
Explain the concept of horizontal gene transfer and its impact on bacterial evolution and antibiotic resistance.
Group 7
This question has two parts. First, answer Part A. Then, answer Part B.
Question 7a
Part A: Which of the following best describes the function of the p53 protein in cells?
It promotes cell cycle progression.
It repairs damaged DNA.
It induces apoptosis in response to DNA damage.
It facilitates DNA replication.
Question 7b
Part B: Mutations in the p53 gene (as described in Part A) are most commonly associated with which condition?
Diabetes
Cancer
Alzheimer's disease
Cystic fibrosis
Group 8
Source: Western Oregon University
Question 8a
In the Michaelis-Menten plot (graph a), what does the horizontal dotted line at Vmax represent?
The point where enzyme activity is inhibited.
The maximum rate of reaction when all enzyme active sites are saturated with substrate.
The rate of reaction at low substrate concentrations.
The point where substrate concentration equals the Michaelis constant (Km).
Question 8b
In the Lineweaver-Burk plot (graph b), what does the x-intercept (-1/Km) indicate?
The enzyme's turnover number.
The substrate concentration at half the maximum velocity.
The inverse of the maximum reaction rate.
The substrate concentration required to achieve Vmax.
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