✈ AFCAT General Awareness20 Questions · No Negative Marking
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Question 1 of 20
Which node is called the natural pacemaker of the heart?
The SA node (Sinoatrial node) located in the right atrium initiates the electrical impulse that triggers each heartbeat. It is called the natural pacemaker of the heart.
Question 2 of 20
The functional unit of the kidney is called the:
The nephron is the structural and functional unit of the kidney. Each kidney contains approximately 1 million nephrons. The glomerulus is only one part within the nephron.
Question 3 of 20
Gas exchange in the lungs takes place at the:
Alveoli are tiny air sacs at the end of bronchioles. Their thin walls and rich blood supply make them the site of oxygen–CO₂ exchange (external respiration).
Question 4 of 20
Which is the largest gland in the human body?
The liver is the largest gland AND largest internal organ in the human body. It performs over 500 functions including bile production, detoxification, and glycogen storage.
Question 5 of 20
Which is the smallest bone in the human body?
The stapes (stirrup bone) in the middle ear is the smallest bone in the human body, measuring only about 3 mm. All three ear ossicles (malleus, incus, stapes) are among the smallest bones.
Question 6 of 20
The pituitary gland is called the "master gland" because it:
The pituitary gland (master gland) secretes tropic hormones that regulate other endocrine glands — thyroid (TSH), adrenal (ACTH), gonads (FSH/LH). It is itself regulated by the hypothalamus.
Question 7 of 20
Insulin hormone is secreted by which cells of the pancreas?
Beta cells (β-cells) of the Islets of Langerhans in the pancreas secrete insulin. Alpha cells secrete glucagon (raises blood sugar). Deficiency of insulin leads to diabetes mellitus.
Question 8 of 20
A reflex arc involves which part of the nervous system as its centre?
A reflex arc uses the spinal cord — NOT the brain — as the integration centre. This allows rapid, automatic responses (like withdrawing hand from heat). The brain becomes aware only after the reflex occurs.
Question 9 of 20
Which enzyme begins starch digestion in the mouth?
Salivary amylase (ptyalin) is secreted by salivary glands and converts starch into maltose in the mouth. Digestion of starch begins in the mouth, not the stomach. Pepsin acts on proteins in the stomach.
Question 10 of 20
The human heart is enclosed in a membrane called the:
The pericardium is the double-walled sac surrounding the heart. Pleura covers lungs; peritoneum lines the abdominal cavity; meninges protect the brain and spinal cord.
Question 11 of 20
Which blood group is known as the "universal donor"?
O− (O negative) is the universal donor because red blood cells lack A, B, or Rh antigens. AB+ is the universal recipient (accepts any blood type).
Question 12 of 20
The largest part of the human brain is the:
The cerebrum is the largest part of the brain (~85% of brain mass). It controls intelligence, memory, voluntary movements, and senses. The cerebellum coordinates balance and posture.
Question 13 of 20
Which part of the eye is responsible for focusing light on the retina?
The lens focuses light precisely on the retina by changing shape (accommodation). The iris regulates light entry through the pupil. The retina converts light into nerve signals.
Question 14 of 20
The process of ultrafiltration of blood occurs in which part of the nephron?
Ultrafiltration occurs at the glomerulus inside Bowman's capsule. Blood pressure forces water, glucose, urea, and salts out of capillaries into the Bowman's capsule — blood cells and large proteins remain behind.
Question 15 of 20
Which hormone is responsible for regulating blood calcium levels?
Parathyroid hormone (PTH) from parathyroid glands raises blood calcium by promoting bone resorption and kidney reabsorption. Calcitonin (from thyroid) lowers calcium — these two hormones are antagonists.
Question 16 of 20
The normal human body temperature is approximately:
Normal human body temperature is 37°C (98.6°F). Fever is generally defined as temperature above 38°C (100.4°F). The hypothalamus acts as the body's thermostat to maintain this temperature.
Question 17 of 20
Which organ produces bile which is stored in the gallbladder?
Bile is produced by the liver and stored in the gallbladder. It is released into the duodenum to emulsify fats (break large fat globules into smaller ones for easier enzyme digestion).
Question 18 of 20
Which vitamin is also called the "sunshine vitamin" because it is synthesised in skin?
Vitamin D (calciferol) is synthesised in the skin by UV sunlight acting on 7-dehydrocholesterol. It is essential for calcium absorption and bone health. Deficiency causes rickets (children) and osteomalacia (adults).
Question 19 of 20
The longest bone in the human body is the:
The femur (thigh bone) is the longest and strongest bone in the human body, constituting about one-quarter of a person's height. The stapes is the smallest (ear); femur is the largest.
Question 20 of 20
The "fight-or-flight" response is primarily triggered by which hormone?
Adrenaline (epinephrine) from adrenal medulla triggers fight-or-flight: increased heart rate, dilated pupils, raised blood sugar, redirected blood to muscles. It prepares the body for immediate action under stress.