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Hesi A2 Biology Practice Set

Question 1 of 35

Which statement correctly distinguishes infection from an inherited disorder?

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Hesi A2 Biology Practice Set Practice Questions

Review these Hesi A2 Biology Practice Set nursing practice questions with answer choices and explanations.

Question 1

Which statement correctly distinguishes infection from an inherited disorder?

  1. Infection involves a microorganism or other infectious agent, whereas an inherited disorder involves transmitted genetic variation
  2. Infection never involves viruses
  3. Inherited disorders spread by coughing
  4. Both always require a bacterium
View answer and explanation

Correct answer:

  1. Infection involves a microorganism or other infectious agent, whereas an inherited disorder involves transmitted genetic variation

Explanation: Infectious and inherited conditions have different causes, although genes can influence susceptibility to infection.

Question 2

What is an asymptomatic infection?

  1. An infection that can never be transmitted
  2. An infection with no infectious agent
  3. An infection without noticeable symptoms
  4. A condition caused only by a broken bone
View answer and explanation

Correct answer:

  1. An infection without noticeable symptoms

Explanation: An infected person may show no symptoms, and transmission may still be possible depending on the pathogen.

Question 3

Which route involves transmission by contaminated food or water after fecal contamination?

  1. Fecal-oral transmission
  2. Diffusion through the placenta in every case
  3. Inheritance through chromosomes
  4. Transfer through a synapse
View answer and explanation

Correct answer:

  1. Fecal-oral transmission

Explanation: Pathogens shed in feces can reach another person's mouth through contaminated material.

Question 4

What is a fomite?

  1. A white blood cell
  2. A type of vitamin
  3. A chromosome pair
  4. A contaminated inanimate object that can help transmit an infectious agent
View answer and explanation

Correct answer:

  1. A contaminated inanimate object that can help transmit an infectious agent

Explanation: Objects such as shared equipment can carry microbes between people.

Question 5

What is an antiseptic generally intended for?

  1. Replacing vaccination
  2. Increasing bacterial reproduction
  3. Sterilizing every internal organ
  4. Reducing microorganisms on living tissue
View answer and explanation

Correct answer:

  1. Reducing microorganisms on living tissue

Explanation: Antiseptics are formulated for use on living tissues such as skin.

Question 6

Which microbial structure can help some bacteria evade phagocytosis?

  1. Capsule
  2. Mitochondrial crista
  3. Human nucleus
  4. Chloroplast
View answer and explanation

Correct answer:

  1. Capsule

Explanation: Certain capsules interfere with recognition or engulfment by immune cells.

Question 7

How does a bacterial toxin differ from the bacterium producing it?

  1. The toxin is always a human chromosome
  2. The toxin can reproduce independently as a cell
  3. The toxin must contain a nucleus
  4. The toxin is a harmful substance, not the entire bacterial cell
View answer and explanation

Correct answer:

  1. The toxin is a harmful substance, not the entire bacterial cell

Explanation: Bacterial toxins are molecules that can damage cells or disrupt physiological processes.

Question 8

Why can antibiotic-resistant bacteria become more common after antibiotic exposure?

  1. Resistance means the patient's body becomes a bacterium
  2. Resistant organisms survive and reproduce while susceptible ones are reduced
  3. Every bacterium deliberately changes its DNA in the same way
  4. Antibiotics convert human cells into bacteria
View answer and explanation

Correct answer:

  1. Resistant organisms survive and reproduce while susceptible ones are reduced

Explanation: Selection favors bacteria with resistance traits; these traits may already exist or be acquired.

Question 9

Which term describes the community of microorganisms living in or on the body?

  1. Nephron
  2. Karyotype
  3. Microbiota
  4. Sarcomere
View answer and explanation

Correct answer:

  1. Microbiota

Explanation: The microbiota includes microorganisms normally associated with body surfaces and habitats.

Question 10

How can normal microbiota help protect a host?

  1. By competing with potential pathogens for space and resources
  2. By stopping all digestion
  3. By making the body permanently sterile
  4. By removing every immune cell
View answer and explanation

Correct answer:

  1. By competing with potential pathogens for space and resources

Explanation: Resident microbes can limit opportunities for invading organisms and influence host defenses.

Question 11

What is immunological tolerance?

  1. The duplication of chromosomes
  2. The ability to digest every protein
  3. Complete inability to respond to pathogens
  4. The ability to avoid inappropriate immune responses to self and certain harmless antigens
View answer and explanation

Correct answer:

  1. The ability to avoid inappropriate immune responses to self and certain harmless antigens

Explanation: Tolerance mechanisms limit harmful responses against the body's own components and other tolerated material.

Question 12

How can complement proteins assist innate defense?

  1. By replacing all antibodies with red cells
  2. By promoting inflammation, marking targets, or damaging microbial membranes
  3. By copying human chromosomes
  4. By producing bile
View answer and explanation

Correct answer:

  1. By promoting inflammation, marking targets, or damaging microbial membranes

Explanation: Complement activation can enhance several mechanisms that help eliminate microbes.

Question 13

What is opsonization?

  1. Copying the target's DNA
  2. Coating a target with molecules that promote phagocytosis
  3. Removing all cell membranes
  4. Turning a bacterium into a virus
View answer and explanation

Correct answer:

  1. Coating a target with molecules that promote phagocytosis

Explanation: Antibodies and certain complement proteins can mark microbes for easier recognition and engulfment.

Question 14

What is a vaccine booster intended to do?

  1. Replace all immune cells
  2. Reinforce an immune response established by earlier vaccination
  3. Change every recessive allele into a dominant allele
  4. Provide an antibiotic in every case
View answer and explanation

Correct answer:

  1. Reinforce an immune response established by earlier vaccination

Explanation: Boosters can renew or strengthen antigen-specific protection and memory responses.

Question 15

A cell has a plasma membrane, cytoplasm, DNA, and ribosomes but no nucleus. Which classification is most likely?

  1. Prokaryote
  2. Typical plant leaf cell
  3. Fungal cell
  4. Human muscle cell
View answer and explanation

Correct answer:

  1. Prokaryote

Explanation: This combination is consistent with a bacterial or archaeal cell.

Question 16

A membrane channel opens and ions move down their electrochemical gradient. Does that movement directly require ATP hydrolysis by the channel?

  1. Yes, because all diffusion is active
  2. No, it is passive movement through a channel
  3. No, because ions never carry charge
  4. Yes, all channel movement consumes ATP directly
View answer and explanation

Correct answer:

  1. No, it is passive movement through a channel

Explanation: Channel-mediated movement down a gradient is passive, though cells may use energy to maintain the gradient.

Question 17

A cell imports a substance using energy stored in another ion's gradient. Which mechanism is this?

  1. Secondary active transport
  2. DNA replication
  3. Simple diffusion
  4. Direct ATP synthesis
View answer and explanation

Correct answer:

  1. Secondary active transport

Explanation: Secondary active transport couples one substance's uphill movement to another's downhill movement.

Question 18

A cell's membrane encloses a droplet of extracellular fluid. Which process is this?

  1. Meiosis
  2. Glycolysis
  3. Exocytosis
  4. Pinocytosis
View answer and explanation

Correct answer:

  1. Pinocytosis

Explanation: Pinocytosis is endocytosis of fluid and dissolved material.

Question 19

What is the benefit of keeping digestive enzymes inside lysosomes?

  1. It causes the cell wall to disappear
  2. It separates many breakdown reactions from other cellular processes
  3. It prevents all digestion
  4. It makes DNA unnecessary
View answer and explanation

Correct answer:

  1. It separates many breakdown reactions from other cellular processes

Explanation: Compartmentalization helps control enzyme activity and limits unintended damage.

Question 20

Why are mitochondrial membranes important for aerobic ATP production?

  1. They maintain compartments and support a proton gradient
  2. They generate antibodies
  3. They make plant cellulose
  4. They store all human chromosomes
View answer and explanation

Correct answer:

  1. They maintain compartments and support a proton gradient

Explanation: The inner membrane separates compartments so electron transport can establish the gradient used by ATP synthase.

Question 21

What does a dominant allele's designation imply under complete dominance?

  1. Its associated phenotype can appear in a heterozygote
  2. It is always beneficial
  3. It contains more DNA than a recessive allele
  4. It is necessarily more common in the population
View answer and explanation

Correct answer:

  1. Its associated phenotype can appear in a heterozygote

Explanation: Dominance concerns expression in heterozygotes, not frequency, size, or usefulness.

Question 22

A recessive condition is autosomal. What does autosomal mean?

  1. The condition is always infectious
  2. The relevant gene must be on the Y chromosome
  3. The relevant gene is on a non-sex chromosome
  4. The gene occurs only in sperm
View answer and explanation

Correct answer:

  1. The relevant gene is on a non-sex chromosome

Explanation: Autosomal genes are located on chromosomes other than the sex chromosomes.

Question 23

Two parents are both homozygous recessive, aa, for a simple trait. What offspring genotype is expected?

  1. AA only
  2. Aa only
  3. AA and Aa only
  4. aa only
View answer and explanation

Correct answer:

  1. aa only

Explanation: Both parents can contribute only the recessive allele a.

Question 24

In an X-linked recessive model, a carrier mother and an unaffected father have a son. What is the son's chance of inheriting the condition-associated allele?

  1. 25%
  2. 0%
  3. 50%
  4. 100%
View answer and explanation

Correct answer:

  1. 50%

Explanation: The son receives Y from his father and has an equal chance of receiving either maternal X.

Question 25

What does variable expressivity mean?

  1. All carriers must show identical symptoms
  2. A gene can never affect phenotype
  3. Chromosomes change number every hour
  4. People with the same associated genotype can show different degrees or features of a trait
View answer and explanation

Correct answer:

  1. People with the same associated genotype can show different degrees or features of a trait

Explanation: Expressivity describes variation in how a trait appears among those expressing it.

Question 26

What is mitochondrial inheritance in humans usually associated with?

  1. Transmission only through the Y chromosome
  2. Transmission only through the father
  3. Transmission through the mother
  4. Transmission without any DNA
View answer and explanation

Correct answer:

  1. Transmission through the mother

Explanation: The embryo normally receives its mitochondria mainly from the egg.

Question 27

Which body system produces hormones that travel through blood to target tissues?

  1. Integumentary system only
  2. Skeletal system only
  3. Endocrine system
  4. Digestive tract lumen only
View answer and explanation

Correct answer:

  1. Endocrine system

Explanation: Endocrine glands release hormones into the circulation to regulate distant tissues.

Question 28

Which organ has both digestive enzyme-secreting and hormone-secreting functions?

  1. Spleen
  2. Pancreas
  3. Trachea
  4. Urinary bladder
View answer and explanation

Correct answer:

  1. Pancreas

Explanation: The pancreas releases digestive enzymes and hormones such as insulin and glucagon.

Question 29

Which process removes carbon dioxide from blood through the lungs?

  1. Absorption through intestinal villi
  2. Filtration into the urinary bladder only
  3. Gas exchange followed by exhalation
  4. DNA replication
View answer and explanation

Correct answer:

  1. Gas exchange followed by exhalation

Explanation: Carbon dioxide diffuses into alveoli and is expelled during breathing.

Question 30

Why can severe diarrhea disturb body function?

  1. It always creates extra chromosomes
  2. It permanently increases blood volume
  3. It makes all dietary protein unnecessary
  4. It can cause loss of water and electrolytes
View answer and explanation

Correct answer:

  1. It can cause loss of water and electrolytes

Explanation: Water and ion losses can disrupt circulation and physiological balance.

Question 31

Which mineral ions are especially important for nerve signaling and membrane potentials?

  1. Sodium and potassium
  2. Iodine and fluoride only
  3. Calcium and iodine only
  4. Iron and zinc only
View answer and explanation

Correct answer:

  1. Sodium and potassium

Explanation: Sodium and potassium gradients are central to many electrical signals in neurons.

Question 32

Which nutrient contains nitrogen and provides amino acids after digestion?

  1. Water
  2. Protein
  3. Starch
  4. Triglyceride
View answer and explanation

Correct answer:

  1. Protein

Explanation: Proteins contain amino acids with nitrogen-containing amino groups.

Question 33

What is the main nutritional role of triglycerides stored in adipose tissue?

  1. Making all antibodies directly
  2. Encoding genetic information
  3. Providing an energy reserve
  4. Transporting oxygen as hemoglobin
View answer and explanation

Correct answer:

  1. Providing an energy reserve

Explanation: Stored triglycerides can be broken down to provide fuel when needed.

Question 34

Why must humans obtain certain fatty acids from their diet?

  1. All fats are toxic unless eaten daily
  2. The body cannot synthesize them in sufficient amounts
  3. They contain human genes
  4. They replace all enzymes
View answer and explanation

Correct answer:

  1. The body cannot synthesize them in sufficient amounts

Explanation: Essential fatty acids must be supplied through food to meet physiological needs.

Question 35

Why is a balanced supply of nutrients important for normal immunity?

  1. Only dietary sugar forms antibodies
  2. Immune cells have no metabolism
  3. Immune cells need energy and building materials to function
  4. Nutrition can replace every immune response
View answer and explanation

Correct answer:

  1. Immune cells need energy and building materials to function

Explanation: Effective defense depends on adequate fuel, amino acids, vitamins, and minerals.