The Biological Basis for Disease in Adults and
Children Questions, Answers And Rationale 2025
Question 1:
What is the primary cause of autosomal dominant genetic diseases?
A) Inheritance of a single mutated allele
B) Inheritance of two mutated alleles
C) Environmental factors
D) Aging of the immune system
Answer: A) Inheritance of a single mutated allele
Rationale: Autosomal dominant diseases are caused by the inheritance of one
mutated allele from either parent. The presence of just one defective allele is
sufficient to express the disease phenotype because dominant genes overpower the
normal allele. Examples include Huntington's disease and Marfan syndrome.
Question 2:
Which of the following best describes the pathophysiology of cystic fibrosis?
A) Dysfunctional potassium channels leading to electrolyte imbalance
B) Defective chloride ion channels resulting in thick mucus secretion
C) Inability to metabolize fats properly
D) Abnormal production of red blood cells leading to anemia
Answer: B) Defective chloride ion channels resulting in thick mucus secretion
Rationale: Cystic fibrosis is a genetic disorder caused by mutations in the CFTR
gene, which codes for chloride ion channels. This defect leads to thick and sticky
mucus in the lungs and other organs, which causes respiratory and digestive
problems. The mucus impairs ciliary clearance, leading to chronic infections and
inflammation.
,Question 3:
Which of the following is the most common cause of respiratory distress in
premature infants?
A) Asthma
B) Cystic fibrosis
C) Respiratory distress syndrome (RDS)
D) Bronchiolitis
Answer: C) Respiratory distress syndrome (RDS)
Rationale: Respiratory distress syndrome (RDS) is the most common cause of
breathing difficulties in premature infants. It occurs due to immature lung
development and insufficient production of surfactant, a substance that helps the
lungs expand and prevents them from collapsing. This leads to poor oxygenation
and difficulty breathing.
Question 4:
Which of the following conditions is associated with the "butterfly-shaped"
rash across the nose and cheeks?
A) Rheumatic fever
B) Systemic lupus erythematosus (SLE)
C) Psoriasis
D) Acne vulgaris
Answer: B) Systemic lupus erythematosus (SLE)
Rationale: The "butterfly-shaped" rash is characteristic of systemic lupus
erythematosus (SLE), an autoimmune disorder. The rash typically appears across
the nose and cheeks and is a common clinical feature of the disease. SLE causes
inflammation and damage to multiple organ systems.
Question 5:
,What is the main characteristic feature of Type 1 diabetes mellitus?
A) Insulin resistance and obesity
B) Insulin deficiency due to autoimmune destruction of pancreatic beta cells
C) Impaired insulin secretion from the liver
D) Excessive insulin production due to metabolic syndrome
Answer: B) Insulin deficiency due to autoimmune destruction of pancreatic beta
cells
Rationale: Type 1 diabetes mellitus is an autoimmune disease in which the body's
immune system attacks and destroys the insulin-producing beta cells in the
pancreas. This results in a complete deficiency of insulin, which is essential for
regulating blood glucose levels.
Question 6:
Which of the following is a common cause of failure to thrive in infants?
A) A hereditary metabolic disorder
B) Inadequate caloric intake or poor feeding
C) Exposure to environmental toxins
D) Immune system deficiency
Answer: B) Inadequate caloric intake or poor feeding
Rationale: Failure to thrive in infants is often caused by inadequate caloric intake
or poor feeding, which may be due to issues such as feeding difficulties,
malnutrition, or gastrointestinal disorders. Although hereditary disorders and
immune system deficiencies can contribute, poor feeding is the most common
cause.
Question 7:
Which of the following is the primary mechanism underlying the development
of atherosclerosis?
, A) Immune system activation leading to arterial plaque formation
B) Chronic high blood pressure causing arterial rupture
C) Endothelial injury and accumulation of lipid deposits in the arterial wall
D) Viral infection of blood vessels leading to inflammation
Answer: C) Endothelial injury and accumulation of lipid deposits in the arterial
wall
Rationale: Atherosclerosis is primarily caused by damage to the endothelial lining
of blood vessels, which leads to the accumulation of lipids (mainly low-density
lipoproteins, or LDL) and other substances in the arterial wall. Over time, these
deposits form plaques, which narrow and harden the arteries, leading to impaired
blood flow.
Question 8:
Which of the following is a characteristic feature of Down syndrome?
A) Extra chromosome 21
B) A missing X chromosome
C) Extra chromosome 18
D) A genetic mutation on the Y chromosome
Answer: A) Extra chromosome 21
Rationale: Down syndrome, also known as trisomy 21, is a genetic condition
caused by the presence of an extra chromosome 21. This leads to developmental
delays, intellectual disabilities, and physical characteristics such as a flat facial
profile and hypotonia.
Question 9:
Which of the following is the most common cause of peptic ulcers in both
adults and children?
A) Excessive alcohol consumption
B) Helicobacter pylori infection
Children Questions, Answers And Rationale 2025
Question 1:
What is the primary cause of autosomal dominant genetic diseases?
A) Inheritance of a single mutated allele
B) Inheritance of two mutated alleles
C) Environmental factors
D) Aging of the immune system
Answer: A) Inheritance of a single mutated allele
Rationale: Autosomal dominant diseases are caused by the inheritance of one
mutated allele from either parent. The presence of just one defective allele is
sufficient to express the disease phenotype because dominant genes overpower the
normal allele. Examples include Huntington's disease and Marfan syndrome.
Question 2:
Which of the following best describes the pathophysiology of cystic fibrosis?
A) Dysfunctional potassium channels leading to electrolyte imbalance
B) Defective chloride ion channels resulting in thick mucus secretion
C) Inability to metabolize fats properly
D) Abnormal production of red blood cells leading to anemia
Answer: B) Defective chloride ion channels resulting in thick mucus secretion
Rationale: Cystic fibrosis is a genetic disorder caused by mutations in the CFTR
gene, which codes for chloride ion channels. This defect leads to thick and sticky
mucus in the lungs and other organs, which causes respiratory and digestive
problems. The mucus impairs ciliary clearance, leading to chronic infections and
inflammation.
,Question 3:
Which of the following is the most common cause of respiratory distress in
premature infants?
A) Asthma
B) Cystic fibrosis
C) Respiratory distress syndrome (RDS)
D) Bronchiolitis
Answer: C) Respiratory distress syndrome (RDS)
Rationale: Respiratory distress syndrome (RDS) is the most common cause of
breathing difficulties in premature infants. It occurs due to immature lung
development and insufficient production of surfactant, a substance that helps the
lungs expand and prevents them from collapsing. This leads to poor oxygenation
and difficulty breathing.
Question 4:
Which of the following conditions is associated with the "butterfly-shaped"
rash across the nose and cheeks?
A) Rheumatic fever
B) Systemic lupus erythematosus (SLE)
C) Psoriasis
D) Acne vulgaris
Answer: B) Systemic lupus erythematosus (SLE)
Rationale: The "butterfly-shaped" rash is characteristic of systemic lupus
erythematosus (SLE), an autoimmune disorder. The rash typically appears across
the nose and cheeks and is a common clinical feature of the disease. SLE causes
inflammation and damage to multiple organ systems.
Question 5:
,What is the main characteristic feature of Type 1 diabetes mellitus?
A) Insulin resistance and obesity
B) Insulin deficiency due to autoimmune destruction of pancreatic beta cells
C) Impaired insulin secretion from the liver
D) Excessive insulin production due to metabolic syndrome
Answer: B) Insulin deficiency due to autoimmune destruction of pancreatic beta
cells
Rationale: Type 1 diabetes mellitus is an autoimmune disease in which the body's
immune system attacks and destroys the insulin-producing beta cells in the
pancreas. This results in a complete deficiency of insulin, which is essential for
regulating blood glucose levels.
Question 6:
Which of the following is a common cause of failure to thrive in infants?
A) A hereditary metabolic disorder
B) Inadequate caloric intake or poor feeding
C) Exposure to environmental toxins
D) Immune system deficiency
Answer: B) Inadequate caloric intake or poor feeding
Rationale: Failure to thrive in infants is often caused by inadequate caloric intake
or poor feeding, which may be due to issues such as feeding difficulties,
malnutrition, or gastrointestinal disorders. Although hereditary disorders and
immune system deficiencies can contribute, poor feeding is the most common
cause.
Question 7:
Which of the following is the primary mechanism underlying the development
of atherosclerosis?
, A) Immune system activation leading to arterial plaque formation
B) Chronic high blood pressure causing arterial rupture
C) Endothelial injury and accumulation of lipid deposits in the arterial wall
D) Viral infection of blood vessels leading to inflammation
Answer: C) Endothelial injury and accumulation of lipid deposits in the arterial
wall
Rationale: Atherosclerosis is primarily caused by damage to the endothelial lining
of blood vessels, which leads to the accumulation of lipids (mainly low-density
lipoproteins, or LDL) and other substances in the arterial wall. Over time, these
deposits form plaques, which narrow and harden the arteries, leading to impaired
blood flow.
Question 8:
Which of the following is a characteristic feature of Down syndrome?
A) Extra chromosome 21
B) A missing X chromosome
C) Extra chromosome 18
D) A genetic mutation on the Y chromosome
Answer: A) Extra chromosome 21
Rationale: Down syndrome, also known as trisomy 21, is a genetic condition
caused by the presence of an extra chromosome 21. This leads to developmental
delays, intellectual disabilities, and physical characteristics such as a flat facial
profile and hypotonia.
Question 9:
Which of the following is the most common cause of peptic ulcers in both
adults and children?
A) Excessive alcohol consumption
B) Helicobacter pylori infection
