Tidal volume in a healthy adult human is approximately:
Answer: A
Tidal volume, the volume of air inspired or expired during normal quiet breathing, is approximately 500 mL in adults.
Q.42Easy
Which neurotransmitter is responsible for the transmission of signals across the neuromuscular junction?
Answer: B
Acetylcholine is the primary neurotransmitter at the neuromuscular junction, binding to nicotinic receptors on muscle fiber membranes to trigger muscle contraction.
Q.43Easy
Which of the following is the primary function of the loop of Henle in the nephron?
Answer: B
The loop of Henle creates a countercurrent multiplier system that establishes an osmotic gradient, enabling selective water reabsorption in the collecting duct.
Q.44Easy
Which organ produces erythropoietin (EPO) in response to low oxygen levels?
Answer: C
The kidneys produce approximately 90% of EPO, which stimulates red blood cell production in bone marrow when oxygen levels are low.
Q.45Easy
Which of the following best describes the role of surfactant in respiratory physiology?
Answer: B
Pulmonary surfactant (lipid + protein) reduces surface tension in alveoli, preventing their collapse during expiration and reducing work of breathing.
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Q.46Easy
Which hormone primarily regulates sodium reabsorption in the distal convoluted tubule and collecting duct?
Answer: B
Aldosterone, released by the adrenal cortex, increases sodium reabsorption via mineralocorticoid receptors in the DCT and collecting duct.
Q.47Easy
During gastric digestion, what is the primary function of pepsin?
Answer: B
Pepsin is a protease activated in the acidic stomach environment, cleaving peptide bonds in proteins to form polypeptides and oligopeptides.
Q.48Easy
A person experiences tremors and rigidity due to dopamine deficiency in the basal ganglia. What is this condition?
Answer: B
Parkinson's disease results from loss of dopaminergic neurons in the substantia nigra, causing dopamine deficiency and characteristic motor symptoms.
Q.49Easy
Which of the following hormones is primarily responsible for regulating blood glucose levels during fasting?
Answer: A
Glucagon is secreted by alpha cells of pancreatic islets during fasting and increases blood glucose by promoting glycogenolysis and gluconeogenesis.
Q.50Easy
The functional unit of the kidney responsible for ultrafiltration is:
Answer: C
The glomerulus with Bowman's capsule forms the renal corpuscle, which is the site of ultrafiltration where small molecules are filtered from blood.
Q.51Easy
During muscle contraction, which protein binds to myosin heads to allow cross-bridge cycling?
Answer: B
Myosin heads bind to specific sites on actin filaments, forming cross-bridges that enable muscle contraction through the sliding filament mechanism.
Q.52Easy
Which of the following represents the correct sequence of blood flow through the heart?
Answer: A
Deoxygenated blood returns to right atrium, passes to right ventricle, pumped to lungs, oxygenated blood returns to left atrium, then left ventricle, and exits via aorta.
Q.53Easy
The resting membrane potential of a neuron is approximately:
Answer: B
The typical resting membrane potential is -70 mV, maintained by the Na+/K+ ATPase pump and selective membrane permeability.
Q.54Easy
Which of the following is the primary site of digestion of carbohydrates?
Answer: A
Carbohydrate digestion begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase and brush border enzymes.
Q.55Easy
In the visual pathway, the structure responsible for focusing light onto the retina is:
Answer: C
The lens adjusts its shape (accommodation) through ciliary muscle contraction to focus light precisely on the retina for clear vision.
Q.56Easy
Which of the following is the basic unit of heredity?
Answer: A
A gene is the fundamental unit of heredity that carries information for a specific trait. It consists of a segment of DNA coding for a protein or RNA.
Q.57Easy
What is the chromosome number in a normal human somatic cell?
Answer: B
Humans have 46 chromosomes (23 pairs) in somatic cells - 22 pairs of autosomes and 1 pair of sex chromosomes (XX or XY).
Q.58Easy
Which law states that traits are inherited through discrete units?
Answer: A
Mendel's Law of Segregation states that hereditary traits are controlled by discrete units (genes) that separate during gamete formation.
Q.59Easy
In a monohybrid cross between two heterozygous individuals (Aa × Aa), what is the probability of homozygous recessive offspring?
Answer: A
Monohybrid cross Aa × Aa produces genotypic ratio 1 AA : 2 Aa : 1 aa. Probability of aa (homozygous recessive) = 41 or 25%.
Q.60Easy
Which of the following best describes alleles?
Answer: A
Alleles are alternative forms of a gene that occupy the same locus on homologous chromosomes and control different variations of the same trait.
