Questions with Correct Answers
100 questions
1. Wet gangrene differs from dry gangrene in that wet gangrene:
A. Is always confined and slow
B. Occurs only in the toes
C. Has no odor
D. Involves bacterial invasion with liquefaction and spreads rapidly
Correct Answer: D. Involves bacterial invasion with liquefaction and spreads rapidly
Rationale: Wet gangrene develops when bacteria invade necrotic tissue, causing swelling, foul odor and
rapid spread with risk of sepsis. Dry gangrene is coagulative, black and well demarcated, often in the
extremities from arterial insufficiency. Gas gangrene from Clostridium produces gas bubbles.
2. Lysosomes function to:
A. Digest worn-out organelles and engulfed material using hydrolytic enzymes
B. Produce ATP
C. Synthesize lipids
D. Package proteins for export
Correct Answer: A. Digest worn-out organelles and engulfed material using hydrolytic
enzymes
Rationale: Lysosomes contain acid hydrolases that break down cellular debris and pathogens
(autophagy and phagocytosis); deficiencies cause storage diseases such as Tay-Sachs. ATP comes from
mitochondria, lipids from smooth ER, and packaging from the Golgi apparatus.
3. A patient with pulmonary tuberculosis has necrotic tissue described as cheese-like. This is:
A. Coagulative necrosis
B. Fat necrosis
C. Caseous necrosis
D. Liquefactive necrosis
Correct Answer: C. Caseous necrosis
Rationale: Caseous necrosis combines coagulative and liquefactive features and appears as a soft,
white, cheesy material in granulomas, typical of TB and some fungal infections. The other types have
different appearances and causes.
,4. During hypoxic cell injury, ATP depletion causes cellular swelling primarily because:
A. The sodium-potassium pump fails, allowing sodium and water to enter the cell
B. Potassium rushes into the cell
C. The cell membrane becomes impermeable
D. Glycogen stores increase
Correct Answer: A. The sodium-potassium pump fails, allowing sodium and water to enter the
cell
Rationale: Without ATP, the Na+/K+-ATPase cannot pump sodium out, so sodium and water accumulate
and the cell swells, an early reversible sign. Potassium leaks out, not in. Anaerobic metabolism depletes
glycogen rather than increasing it.
5. Cellular aging is partly explained by the shortening of:
A. Mitochondria
B. Cell membranes
C. Telomeres at the ends of chromosomes with each division
D. Ribosomes
Correct Answer: C. Telomeres at the ends of chromosomes with each division
Rationale: Telomeres protect chromosome ends and shorten with each replication until cells stop dividing
(replicative senescence). Cancer cells often reactivate telomerase to divide indefinitely. The other
structures do not shorten this way.
6. Cyanide poisoning causes cell injury by:
A. Blocking cytochrome oxidase in the mitochondria so cells cannot use oxygen
B. Binding hemoglobin more strongly than oxygen
C. Causing bronchospasm
D. Lysing red blood cells
Correct Answer: A. Blocking cytochrome oxidase in the mitochondria so cells cannot use
oxygen
Rationale: Cyanide inhibits the electron transport chain, causing histotoxic hypoxia even when blood
oxygen levels are normal; venous blood stays bright red. CO binds hemoglobin. Bronchospasm and
hemolysis are not the mechanism.
,7. Autophagy helps cells survive nutrient deprivation by:
A. Dividing rapidly
B. Digesting their own components to recycle nutrients
C. Absorbing extra oxygen
D. Releasing histamine
Correct Answer: B. Digesting their own components to recycle nutrients
Rationale: Autophagy (self-eating) uses lysosomes to break down organelles and proteins for energy and
recycling during stress. Excess autophagy can contribute to cell death. Rapid division, oxygen absorption
and histamine release are not related.
8. A leg immobilized in a cast for 6 weeks becomes visibly smaller. The muscle cells have
undergone:
A. Hypertrophy
B. Disuse atrophy
C. Metaplasia
D. Hyperplasia
Correct Answer: B. Disuse atrophy
Rationale: Reduced workload decreases protein synthesis and increases breakdown, shrinking cells to
conserve energy. Atrophy can also result from denervation, poor nutrition, reduced blood supply or loss of
hormonal stimulation. The other adaptations increase size or number or change cell type.
9. Which disorder is inherited in an autosomal recessive pattern?
A. Cystic fibrosis
B. Huntington disease
C. Marfan syndrome
D. Neurofibromatosis type 1
Correct Answer: A. Cystic fibrosis
Rationale: Cystic fibrosis results from two mutated CFTR alleles. Huntington disease, Marfan syndrome
and neurofibromatosis are autosomal dominant. Other recessive disorders include sickle cell disease,
PKU and Tay-Sachs.
, 10. Translation of mRNA into a polypeptide occurs at the:
A. Nucleus
B. Golgi apparatus
C. Lysosome
D. Ribosome
Correct Answer: D. Ribosome
Rationale: Ribosomes read mRNA codons and tRNA delivers matching amino acids to build the protein.
The nucleus is the site of transcription. The Golgi modifies and packages proteins, and lysosomes digest
material.
11. Normal human somatic cells contain:
A. 23 chromosomes
B. 48 chromosomes
C. 44 chromosomes total
D. 46 chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes
Correct Answer: D. 46 chromosomes: 22 pairs of autosomes and 1 pair of sex chromosomes
Rationale: Somatic cells are diploid with 46 chromosomes. Gametes are haploid with 23 chromosomes,
produced by meiosis. Additional or missing chromosomes cause aneuploidy, such as trisomy 21.
12. A mutation in the BRCA1 or BRCA2 gene increases lifetime risk of:
A. Breast and ovarian cancer
B. Lung cancer only
C. Huntington disease
D. Hemophilia
Correct Answer: A. Breast and ovarian cancer
Rationale: BRCA genes are tumor suppressors involved in DNA repair; inherited mutations greatly raise
breast and ovarian cancer risk and also prostate and pancreatic cancer. They follow autosomal dominant
inheritance with incomplete penetrance.