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DAT PAT practice questions

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Question 1Survey of the Natural Sciences

Which cellular organelle is the primary site of ATP production via oxidative phosphorylation in a typical eukaryotic cell?

  1. Golgi apparatus
  2. Mitochondrion Correct answer.
  3. Lysosome
  4. Ribosome

Explanation

The inner mitochondrial membrane houses the electron transport chain and ATP synthase, which together carry out oxidative phosphorylation. Ribosomes synthesize proteins, the Golgi modifies and packages them, and lysosomes degrade material, so none of those organelles generate ATP on this scale.

Question 2Survey of the Natural Sciences

In DNA, adenine pairs with thymine through how many hydrogen bonds?

  1. Three
  2. Four
  3. One
  4. Two Correct answer.

Explanation

Adenine and thymine form two hydrogen bonds, while guanine and cytosine form three. This difference explains why GC-rich regions of DNA require higher temperatures to separate.

Question 3Survey of the Natural Sciences

A mutation changes a codon from UAC to UAA. What is the most likely consequence for the resulting polypeptide?

  1. Premature termination of translation Correct answer.
  2. A single amino acid substitution
  3. A frameshift affecting all downstream codons
  4. No change to the polypeptide sequence

Explanation

UAA is a stop codon, so the ribosome releases the transcript early, producing a truncated protein. A substitution would require the new codon to specify a different amino acid, and a frameshift requires an insertion or deletion, neither of which occurred here.

Question 4Survey of the Natural Sciences

Which blood vessel carries oxygenated blood from the lungs to the heart?

  1. Pulmonary artery
  2. Pulmonary vein Correct answer.
  3. Superior vena cava
  4. Aorta

Explanation

Pulmonary veins return oxygenated blood from the lungs to the left atrium, an exception to the general rule that veins carry deoxygenated blood. The pulmonary artery carries deoxygenated blood away from the heart toward the lungs.

Question 5Survey of the Natural Sciences

Which process directly produces the greatest yield of ATP during aerobic cellular respiration?

  1. The citric acid cycle
  2. Oxidative phosphorylation Correct answer.
  3. Pyruvate oxidation
  4. Glycolysis

Explanation

Oxidative phosphorylation generates the majority of ATP through the proton gradient and ATP synthase. Glycolysis and the citric acid cycle produce small amounts of substrate-level ATP and mainly yield reduced electron carriers that feed oxidative phosphorylation.

Question 6Survey of the Natural Sciences

Two heterozygous individuals (Aa × Aa) are crossed for a trait showing complete dominance. What fraction of offspring are expected to show the recessive phenotype?

  1. Three quarters
  2. One quarter Correct answer.
  3. Zero
  4. One half

Explanation

An Aa × Aa cross yields a 1:2:1 genotypic ratio (AA:Aa:aa), so one quarter of offspring are homozygous recessive and display the recessive phenotype. The remaining three quarters carry at least one dominant allele and show the dominant phenotype.

Question 7Survey of the Natural Sciences

Which structure in the nephron is primarily responsible for reabsorbing the majority of filtered water and solutes?

  1. Glomerulus
  2. Proximal convoluted tubule Correct answer.
  3. Collecting duct
  4. Loop of Henle

Explanation

The proximal convoluted tubule reabsorbs roughly two thirds of filtered water and sodium through its extensive microvilli. The glomerulus performs filtration rather than reabsorption, and the loop and collecting duct handle later fine-tuning under hormonal control.

Question 8Survey of the Natural Sciences

Which hormone is released by the posterior pituitary and increases water reabsorption in the collecting duct?

  1. Insulin
  2. Aldosterone
  3. Antidiuretic hormone Correct answer.
  4. Thyroxine

Explanation

Antidiuretic hormone, also called vasopressin, is released from the posterior pituitary and inserts aquaporins into collecting duct membranes to increase water reabsorption. Aldosterone acts on sodium reabsorption, insulin regulates glucose, and thyroxine governs metabolic rate.

Question 9Survey of the Natural Sciences

A neuron at resting membrane potential is most permeable to which ion?

  1. Chloride
  2. Calcium
  3. Potassium Correct answer.
  4. Sodium

Explanation

At rest, potassium leak channels dominate membrane permeability, so the resting potential sits near the potassium equilibrium potential. Sodium permeability is low at rest but rises sharply during an action potential.

Question 10Survey of the Natural Sciences

Which type of muscle tissue is characterized by intercalated discs and involuntary contraction?

  1. Skeletal muscle
  2. Cardiac muscle Correct answer.
  3. Tendon tissue
  4. Smooth muscle

Explanation

Cardiac muscle is striated, involuntary, and connected by intercalated discs containing gap junctions that synchronize contraction. Skeletal muscle is voluntary, smooth muscle lacks intercalated discs, and tendon is connective tissue rather than muscle.

Question 11Survey of the Natural Sciences

In a population at Hardy-Weinberg equilibrium, the frequency of the recessive allele is 0.2. What is the expected frequency of heterozygotes?

  1. 0.32 Correct answer.
  2. 0.64
  3. 0.04
  4. 0.16

Explanation

With q = 0.2, p = 0.8, and heterozygote frequency is 2pq = 2(0.8)(0.2) = 0.32. The value q² = 0.04 represents homozygous recessive individuals, not heterozygotes.

Question 12Survey of the Natural Sciences

Which of the following best describes the role of natural selection in evolution?

  1. It changes allele frequencies based on differential reproductive success Correct answer.
  2. It prevents mutations from occurring in a population
  3. It creates new alleles in response to environmental needs
  4. It guarantees that populations become more complex over time

Explanation

Natural selection acts on existing heritable variation, favoring traits that increase reproductive success and thereby shifting allele frequencies across generations. It does not generate new alleles on demand, ensure increasing complexity, or block mutation.

Question 13Survey of the Natural Sciences

Which class of macromolecules includes enzymes that catalyze metabolic reactions?

  1. Nucleic acids
  2. Lipids
  3. Carbohydrates
  4. Proteins Correct answer.

Explanation

Enzymes are proteins whose specific three-dimensional shapes create active sites that lower activation energy. Carbohydrates serve mainly as energy sources and structural components, lipids as membranes and signaling molecules, and nucleic acids as genetic information carriers.

Question 14Survey of the Natural Sciences

A student observes cells with a rigid cell wall, chloroplasts, and a large central vacuole. These cells most likely come from which organism?

  1. A mushroom
  2. A bacterium
  3. A flowering plant Correct answer.
  4. A mammal

Explanation

Chloroplasts and a large central vacuole together with a cell wall identify a photosynthetic plant cell. Fungal walls lack chloroplasts, animal cells lack walls and chloroplasts, and bacteria lack membrane-bound chloroplasts and a large central vacuole.

Question 15Survey of the Natural Sciences

Which statement correctly describes the relationship between photosynthesis and cellular respiration?

  1. Photosynthesis stores energy in organic molecules, and respiration releases it Correct answer.
  2. Both processes occur only in the dark
  3. Respiration produces glucose that photosynthesis then breaks down
  4. Photosynthesis releases carbon dioxide, and respiration consumes oxygen

Explanation

Photosynthesis uses light energy to build glucose, storing energy in chemical bonds, while cellular respiration oxidizes glucose to release that energy as ATP. The two processes are complementary in both gas exchange and energy flow.

Question 16Survey of the Natural Sciences

During which phase of mitosis do sister chromatids separate and move toward opposite poles?

  1. Anaphase Correct answer.
  2. Metaphase
  3. Prophase
  4. Telophase

Explanation

Anaphase begins when cohesin is cleaved and sister chromatids are pulled to opposite poles by shortening spindle microtubules. Prophase involves condensation, metaphase aligns chromosomes, and telophase reforms nuclei.

Question 17Survey of the Natural Sciences

Which of the following is the best example of a density-dependent factor limiting a population?

  1. A sudden frost
  2. A severe drought
  3. A volcanic eruption
  4. Competition for nesting sites Correct answer.

Explanation

Density-dependent factors intensify as population density rises, and competition for limited nesting sites is a classic example because its effect grows with crowding. Drought, eruptions, and frost are density-independent because their impact does not depend on population size.

Question 18Survey of the Natural Sciences

In a food web, which trophic level typically contains the smallest total biomass?

  1. Secondary consumers
  2. Tertiary consumers Correct answer.
  3. Primary consumers
  4. Producers

Explanation

Energy is lost at each trophic transfer, roughly ninety percent at each step, so higher trophic levels support less biomass. Tertiary consumers therefore occupy the smallest biomass pool in most food webs.

Question 19Survey of the Natural Sciences

Which molecule serves as the direct energy currency for most cellular work?

  1. ATP Correct answer.
  2. Glucose
  3. NADH
  4. Cholesterol

Explanation

ATP couples exergonic reactions to endergonic ones by transferring a phosphate group, making it the direct energy currency of the cell. Glucose and NADH store energy that must first be converted into ATP, and cholesterol is a structural lipid.

Question 20Survey of the Natural Sciences

A child inherits a mitochondrial disorder only from the mother. Which pattern of inheritance does this illustrate?

  1. Autosomal recessive
  2. Autosomal dominant
  3. Maternal inheritance Correct answer.
  4. X-linked recessive

Explanation

Mitochondrial DNA is inherited almost exclusively from the mother because the zygote's mitochondria derive from the oocyte. Autosomal and X-linked patterns involve nuclear genes and do not explain transmission restricted to maternal lineage.

Question 21Survey of the Natural Sciences

Which enzyme unwinds the DNA double helix ahead of the replication fork?

  1. Helicase Correct answer.
  2. DNA polymerase
  3. Ligase
  4. Primase

Explanation

Helicase breaks the hydrogen bonds between complementary strands, separating them to expose templates for replication. Polymerase synthesizes new strands, ligase joins fragments, and primase lays down RNA primers.

Question 22Survey of the Natural Sciences

A solution with a pH of 3 is how many times more acidic than a solution with a pH of 5?

  1. 10 times
  2. 100 times Correct answer.
  3. 2 times
  4. 1000 times

Explanation

Because pH is a negative logarithmic scale, each unit represents a tenfold change in hydrogen ion concentration. A difference of two pH units therefore corresponds to 10², or 100 times greater acidity.

Question 23Survey of the Natural Sciences

An individual with genotype AaBb is testcrossed. Assuming independent assortment, what proportion of offspring are expected to be aabb?

  1. 1/4 Correct answer.
  2. 1/8
  3. 1/16
  4. 1/2

Explanation

A testcross uses a homozygous recessive partner (aabb), so the question reduces to the probability that AaBb produces an ab gamete. That probability is 1/2 × 1/2 = 1/4, and every ab gamete paired with an ab gamete yields aabb offspring.

Question 24Survey of the Natural Sciences

Which property of water allows insects such as water striders to walk on a pond surface?

  1. Universal solvent behavior
  2. High specific heat
  3. Cohesion and surface tension Correct answer.
  4. Low density as a solid

Explanation

Hydrogen bonding among water molecules creates strong cohesion, and at the surface this produces surface tension capable of supporting small organisms. High specific heat, ice density, and solvent behavior are real properties of water but do not explain surface support.

Question 25Survey of the Natural Sciences

A population of bacteria is exposed to an antibiotic, and a few cells survive and reproduce. Over many generations, the population becomes resistant. Which mechanism best explains this outcome?

  1. Selection of pre-existing resistant variants Correct answer.
  2. Random extinction of susceptible lineages only
  3. Inheritance of acquired resistance from exposure
  4. Directed mutation induced by the antibiotic

Explanation

Resistance arises from pre-existing genetic variation; the antibiotic kills susceptible cells and allows resistant variants to proliferate. Mutations are random rather than directed by the drug, and acquired traits are not inherited in this manner.

Question 26Survey of the Natural Sciences

A molecule of glucose is completely oxidized during aerobic respiration. In which of the following locations does the majority of ATP production occur?

  1. Inner mitochondrial membrane Correct answer.
  2. Cytosol
  3. Outer mitochondrial membrane
  4. Mitochondrial matrix

Explanation

The majority of ATP during aerobic respiration is produced by oxidative phosphorylation, which occurs on the inner mitochondrial membrane where the electron transport chain and ATP synthase are located. The matrix houses the citric acid cycle, which produces some ATP but far less than the electron transport chain.

Question 27Survey of the Natural Sciences

Which of the following best describes the function of the sodium-potassium pump in maintaining the resting membrane potential of a neuron?

  1. It imports three sodium ions and exports two potassium ions, creating a net positive charge inside.
  2. It allows both sodium and potassium ions to diffuse freely across the membrane.
  3. It moves sodium and potassium ions down their concentration gradients without using ATP.
  4. It exports three sodium ions and imports two potassium ions, creating a net negative charge inside. Correct answer.

Explanation

The sodium-potassium pump uses ATP to move three sodium ions out of the cell and two potassium ions into the cell, resulting in a net loss of one positive charge from the interior. This electrogenic action contributes to the negative resting membrane potential.

Question 28Survey of the Natural Sciences

A woman with blood type AB marries a man with blood type O. What are the possible blood types of their children?

  1. Type A, type B, or type AB
  2. Type AB or type O
  3. Type A or type B Correct answer.
  4. Type O only

Explanation

The woman with type AB has genotype IAIB, and the man with type O has genotype ii. Their children can inherit either IA or IB from the mother and i from the father, resulting in genotype IAi (type A) or IBi (type B).

Question 29Survey of the Natural Sciences

Which of the following is the primary role of the loop of Henle in the mammalian kidney?

  1. Filtering blood plasma to form the initial filtrate
  2. Secreting hydrogen ions to regulate blood pH
  3. Establishing a concentration gradient in the medulla that allows water reabsorption Correct answer.
  4. Reabsorbing glucose and amino acids from the filtrate

Explanation

The loop of Henle creates a hyperosmotic environment in the renal medulla through the countercurrent multiplier system, which enables water to be reabsorbed from the collecting duct under the influence of ADH. This mechanism is essential for concentrating urine.

Question 30Survey of the Natural Sciences

During DNA replication, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

  1. Helicase
  2. Primase
  3. DNA polymerase III
  4. DNA ligase Correct answer.

Explanation

DNA ligase catalyzes the formation of phosphodiester bonds between adjacent nucleotides, sealing the nicks between Okazaki fragments to create a continuous DNA strand. This action is essential for completing synthesis of the lagging strand.

Question 31Survey of the Natural Sciences

Which of the following best explains why the human population has experienced a rapid increase in recent centuries according to demographic transition theory?

  1. Death rates declined due to improved sanitation and medicine while birth rates remained high. Correct answer.
  2. Birth rates and death rates both declined simultaneously.
  3. Birth rates increased dramatically due to improved nutrition and healthcare.
  4. Death rates increased due to urbanization and poor living conditions.

Explanation

In the early stages of demographic transition, improvements in sanitation, medicine, and food supply reduce mortality, especially infant mortality, while birth rates remain high. This gap between birth and death rates leads to rapid population growth.

Question 32Survey of the Natural Sciences

Which of the following is the most likely consequence of a mutation that changes a single nucleotide in the third position of a codon?

  1. The reading frame will shift, altering all subsequent amino acids.
  2. The amino acid sequence may remain unchanged due to the redundancy of the genetic code. Correct answer.
  3. The mutation will always result in a different amino acid being incorporated.
  4. The protein will always be truncated and nonfunctional.

Explanation

The genetic code is degenerate, meaning that multiple codons can specify the same amino acid. A change in the third base of a codon often results in a synonymous (silent) mutation, leaving the amino acid sequence unchanged.

Question 33Survey of the Natural Sciences

Which of the following structures is primarily responsible for the production of cerebrospinal fluid in the human brain?

  1. Meninges
  2. Ventricles
  3. Corpus callosum
  4. Choroid plexus Correct answer.

Explanation

The choroid plexus is a network of capillaries located in the walls of the ventricles that produces cerebrospinal fluid. This fluid cushions the brain and spinal cord and helps maintain a stable environment.

Question 34Survey of the Natural Sciences

A plant is exposed to a prolonged period of darkness. Which of the following processes will be most directly affected?

  1. The Calvin cycle will continue at the same rate because it does not require light.
  2. The light-dependent reactions of photosynthesis will cease, reducing ATP and NADPH production. Correct answer.
  3. Stomatal opening will increase to capture more light.
  4. Cellular respiration will stop because it requires light.

Explanation

The light-dependent reactions require light energy to generate ATP and NADPH, which are then used in the Calvin cycle. In prolonged darkness, these reactions stop, and the Calvin cycle will soon slow due to lack of ATP and NADPH.

Question 35Survey of the Natural Sciences

Which of the following best describes the principle of independent assortment?

  1. Alleles of the same gene separate from each other during meiosis.
  2. All alleles from one parent are inherited together as a unit.
  3. Alleles of different genes segregate independently of one another during gamete formation. Correct answer.
  4. Genes located close together on the same chromosome are always inherited together.

Explanation

The principle of independent assortment states that alleles of different genes are distributed to gametes independently of one another, provided the genes are on different chromosomes or far apart on the same chromosome. This principle explains the 9:3:3:1 phenotypic ratio in dihybrid crosses.

Question 36Survey of the Natural Sciences

Which of the following is the primary function of the rough endoplasmic reticulum in a eukaryotic cell?

  1. Synthesis and processing of proteins destined for secretion or membrane insertion Correct answer.
  2. Generation of ATP through oxidative phosphorylation
  3. Synthesis of lipids and detoxification of drugs
  4. Modification and packaging of proteins for transport

Explanation

The rough endoplasmic reticulum is studded with ribosomes and is the site of synthesis for secretory proteins, membrane proteins, and proteins destined for lysosomes. It also performs initial processing such as folding and glycosylation.

Question 37Survey of the Natural Sciences

A population of insects is exposed to a new insecticide. After several generations, the population becomes resistant. Which of the following best explains this observation?

  1. Pre-existing genetic variation included individuals with resistance, which survived and reproduced. Correct answer.
  2. The insecticide induced a physiological change in all individuals that was inherited.
  3. The insects learned to avoid the insecticide and passed this behavior to offspring.
  4. The insecticide caused mutations that made individuals resistant.

Explanation

Natural selection acts on existing genetic variation. In this case, some individuals already possessed alleles conferring resistance, and these individuals survived and reproduced, increasing the frequency of resistance alleles in the population.

Question 38Survey of the Natural Sciences

Which of the following is a key difference between mitosis and meiosis?

  1. Mitosis occurs only in gametes, while meiosis occurs in somatic cells.
  2. Mitosis involves two rounds of cell division, while meiosis involves one.
  3. Mitosis results in crossing over, while meiosis does not.
  4. Mitosis produces two genetically identical diploid cells, while meiosis produces four genetically diverse haploid cells. Correct answer.

Explanation

Mitosis is a single division that yields two daughter cells with the same chromosome number as the parent, typically diploid and genetically identical. Meiosis consists of two divisions and produces four haploid cells that are genetically distinct due to crossing over and independent assortment.

Question 39Survey of the Natural Sciences

Which of the following best describes the role of the enzyme amylase in the digestive system?

  1. It neutralizes stomach acid in the small intestine.
  2. It emulsifies fats to increase surface area for digestion.
  3. It breaks down proteins into amino acids.
  4. It hydrolyzes starch into smaller sugars such as maltose. Correct answer.

Explanation

Amylase is a digestive enzyme that catalyzes the hydrolysis of starch into maltose and other smaller oligosaccharides. It is present in saliva and pancreatic juice.

Question 40Survey of the Natural Sciences

In a certain species of plant, flower color is controlled by a single gene with incomplete dominance. Red-flowered plants (RR) crossed with white-flowered plants (rr) produce pink-flowered offspring (Rr). If two pink-flowered plants are crossed, what proportion of the offspring will have red flowers?

  1. 3/4
  2. 1/4 Correct answer.
  3. 0
  4. 1/2

Explanation

A cross between two heterozygous pink plants (Rr × Rr) yields a genotypic ratio of 1 RR : 2 Rr : 1 rr. The RR genotype produces red flowers, so one-quarter of the offspring will be red.

Question 41Survey of the Natural Sciences

Which of the following is the primary function of the alveoli in the respiratory system?

  1. To filter pathogens from the air
  2. To provide a large surface area for gas exchange between air and blood Correct answer.
  3. To warm and humidify incoming air
  4. To produce sound through vibration

Explanation

Alveoli are tiny air sacs with thin walls and a rich capillary network, providing a large surface area for the diffusion of oxygen into the blood and carbon dioxide out. Their structure maximizes gas exchange efficiency.

Question 42Survey of the Natural Sciences

A researcher discovers a new organism that is multicellular, heterotrophic, and has cell walls made of chitin. To which kingdom does this organism most likely belong?

  1. Protista
  2. Animalia
  3. Plantae
  4. Fungi Correct answer.

Explanation

Fungi are multicellular heterotrophs with cell walls composed of chitin. They obtain nutrients by absorption, which distinguishes them from plants and animals.

Question 43Survey of the Natural Sciences

Which of the following best explains why a person with a severe deficiency in ADH (antidiuretic hormone) would produce large volumes of dilute urine?

  1. Without ADH, the collecting duct remains impermeable to water, preventing water reabsorption. Correct answer.
  2. Without ADH, the loop of Henle cannot establish a concentration gradient.
  3. Without ADH, the glomerulus cannot filter blood effectively.
  4. Without ADH, sodium reabsorption in the proximal tubule is inhibited.

Explanation

ADH increases the permeability of the collecting duct to water by inserting aquaporin channels. In its absence, water cannot be reabsorbed from the filtrate, leading to the excretion of large volumes of dilute urine, a condition known as diabetes insipidus.

Question 44Survey of the Natural Sciences

Which of the following is a characteristic of an r-selected species?

  1. Stable population size near carrying capacity
  2. Late maturity and long lifespan
  3. Production of few, large offspring
  4. High reproductive rate with little parental care Correct answer.

Explanation

r-selected species are characterized by rapid reproduction, high fecundity, small body size, and little to no parental investment. They thrive in unstable environments and often exhibit exponential growth when resources are abundant.

Question 45Survey of the Natural Sciences

Which of the following is the correct sequence of events during the sliding filament model of muscle contraction?

  1. Tropomyosin binds to calcium, exposing myosin-binding sites on actin.
  2. Calcium binds to troponin, tropomyosin moves, myosin binds to actin, and the power stroke occurs. Correct answer.
  3. Acetylcholine binds to receptors, calcium is released, and myosin heads detach from actin.
  4. ATP binds to myosin, causing it to bind more strongly to actin.

Explanation

In the sliding filament model, calcium ions bind to troponin, causing tropomyosin to shift and expose myosin-binding sites on actin. Myosin heads then bind to actin and perform a power stroke, sliding the filaments past each other.

Question 46Survey of the Natural Sciences

A couple has a child with cystic fibrosis, an autosomal recessive disorder. Both parents are phenotypically normal. What is the probability that their next child will be a carrier of the cystic fibrosis allele?

  1. 1/4
  2. 1/2 Correct answer.
  3. 3/4
  4. 0

Explanation

Since the child has cystic fibrosis (cc), both parents must be carriers (Cc). A cross between two carriers yields a 1:2:1 genotypic ratio: 1 CC : 2 Cc : 1 cc. Thus, the probability of a carrier (Cc) child is 2/4, or 1/2.

Question 47Survey of the Natural Sciences

Which of the following best describes the role of the enzyme reverse transcriptase in retroviruses such as HIV?

  1. It synthesizes a DNA strand complementary to the viral RNA genome. Correct answer.
  2. It replicates the viral RNA genome for packaging into new virions.
  3. It directly translates viral RNA into proteins.
  4. It integrates viral DNA into the host genome.

Explanation

Reverse transcriptase catalyzes the synthesis of a DNA copy from an RNA template, a process called reverse transcription. This DNA is then integrated into the host genome by integrase.

Question 48Survey of the Natural Sciences

Which of the following is an example of a post-translational modification that can regulate protein function?

  1. Addition of a poly-A tail to mRNA
  2. Splicing of introns from pre-mRNA
  3. Binding of a transcription factor to a promoter
  4. Phosphorylation of specific amino acid residues Correct answer.

Explanation

Phosphorylation is a common post-translational modification in which phosphate groups are added to serine, threonine, or tyrosine residues, altering protein activity, localization, or interactions. It occurs after translation.

Question 49Survey of the Natural Sciences

A population of birds has a range of beak sizes. During a drought, only birds with very large beaks can crack the available hard seeds, while small-beaked birds starve. After several generations, the average beak size increases significantly. This is an example of which type of selection?

  1. Stabilizing selection
  2. Directional selection Correct answer.
  3. Sexual selection
  4. Disruptive selection

Explanation

Directional selection occurs when individuals with a phenotype at one extreme of the distribution have higher fitness, shifting the population mean toward that extreme. Here, large beak size is favored, so the average beak size increases.

Question 50Survey of the Natural Sciences

Which of the following is the most likely effect of a mutation that inactivates the tumor suppressor gene p53?

  1. DNA repair mechanisms will be upregulated.
  2. Cells with damaged DNA may continue to divide, increasing cancer risk. Correct answer.
  3. Apoptosis of cells with DNA damage will be enhanced.
  4. The cell cycle will be arrested at the G1 checkpoint.

Explanation

p53 is a tumor suppressor that normally halts the cell cycle or triggers apoptosis in response to DNA damage. Inactivation of p53 allows cells with damaged DNA to survive and proliferate, promoting tumor formation.