Question 1

Which vitamin is synthesized by the human body when skin is exposed to sunlight?

Accepted Answer

Vitamin D is synthesized in the skin when exposed to ultraviolet B (UVB) radiation from sunlight. This vitamin is essential for calcium absorption and bone health.

Question 2

Which of the following is the primary function of haemoglobin in the human body?

Accepted Answer

Haemoglobin is an iron-containing protein in red blood cells that binds to oxygen in the lungs and transports it to tissues throughout the body. It also carries carbon dioxide back to the lungs for exhalation.

Question 3

How many chambers does the human heart have?

Accepted Answer

The human heart has four chambers: two upper chambers called atria (right and left) and two lower chambers called ventricles (right and left). The right side pumps deoxygenated blood to the lungs, and the left side pumps oxygenated blood to the body.

Question 4

What is the normal range of pH in the human blood?

Accepted Answer

The normal pH of human blood is maintained between 7.35 and 7.45, which is slightly alkaline. This narrow range is critical for enzyme function and cellular processes.

Question 5

Which of the following glands is responsible for regulating metabolism and body temperature?

Accepted Answer

The thyroid gland secretes thyroid hormones (T3 and T4) that regulate metabolic rate, energy production, and body temperature. It is located in the neck below the larynx.

Question 6

Which of the following is the primary function of hemoglobin in the human body?

Accepted Answer

Hemoglobin is an iron-containing protein found in red blood cells (RBCs) that binds to oxygen in the lungs and transports it to tissues throughout the body. It also carries carbon dioxide back to the lungs for exhalation.

Question 7

Which of the following vitamins is synthesized by the human body and does NOT need to be obtained from external dietary sources?

Accepted Answer

Vitamin D is synthesized in the skin when exposed to sunlight (UV-B radiation), making it unique among essential vitamins. While other vitamins like A, B12, and C must be obtained from food sources, Vitamin D can be produced endogenously.

Question 8

How many chambers does the human heart have, and what is the primary function of the right atrium?

Accepted Answer

The human heart has 4 chambers: two atria (right and left) and two ventricles (right and left). The right atrium receives deoxygenated blood from the superior and inferior vena cava and pumps it into the right ventricle.

Question 9

Which of the following is the correct sequence of blood flow through the heart?

Accepted Answer

The correct sequence is: Deoxygenated blood enters the right atrium → right ventricle → lungs (via pulmonary artery) → oxygenated blood returns to left atrium → left ventricle → body (via aorta).

Question 10

Which hormone is primarily responsible for regulating blood glucose levels, and which organ produces it?

Accepted Answer

Insulin is the primary hormone that lowers blood glucose levels by promoting glucose uptake into cells. It is produced by beta cells in the islets of Langerhans located in the pancreas.

Question 11

Which of the following statements about red blood cells (RBCs) in humans is CORRECT?

Accepted Answer

Mature mammalian red blood cells lack a nucleus and mitochondria, allowing more space for hemoglobin. They are biconcave discs that live approximately 120 days and are produced in bone marrow.

Question 12

Which of the following hormones is primarily responsible for regulating blood glucose levels by promoting the uptake of glucose into cells?

Accepted Answer

Insulin is a hormone produced by the beta cells of the pancreas (specifically in the islets of Langerhans). It lowers blood glucose by facilitating glucose uptake into muscle, fat, and liver cells, and promoting glycogen synthesis. This is a fundamental concept in human physiology tested at SSC GD level.

Question 13

Which of the following hormones is produced by the pancreas and plays a crucial role in regulating blood glucose levels by facilitating glucose uptake into cells?

Accepted Answer

Insulin is a peptide hormone secreted by beta cells (β-cells) of the islets of Langerhans in the pancreas. It lowers blood glucose by promoting glucose uptake in muscle and adipose tissue, and stimulates glycogen synthesis in the liver. Deficiency or dysfunction of insulin leads to diabetes mellitus.

Question 14

The human circulatory system consists of the heart, blood vessels, and blood. Which of the following statements about blood pressure is CORRECT?

Accepted Answer

Normal systolic/diastolic blood pressure in a healthy adult is approximately 120/80 mmHg. Systolic pressure (top number) is the pressure when the heart contracts; diastolic pressure (bottom number) is when the heart relaxes. Blood pressure above 140/90 mmHg is classified as hypertension.

Question 15

Which vitamin is synthesized by the human body when skin is exposed to sunlight, and its deficiency leads to rickets in children and osteomalacia in adults?

Accepted Answer

Vitamin D (cholecalciferol) is synthesized in the skin when exposed to ultraviolet B (UVB) radiation from sunlight. It is essential for calcium absorption in the intestines and bone mineralization. Deficiency causes rickets (bone deformity in children) and osteomalacia (soft bones in adults). Unlike most other vitamins, the body can produce vitamin D endogenously.

Question 16

The human respiratory system exchanges gases between the blood and the atmosphere. Which of the following is the PRIMARY site of gas exchange in the lungs?

Accepted Answer

The alveoli (singular: alveolus) are the primary functional units of gas exchange in the lungs. These are tiny, thin-walled air sacs surrounded by a dense network of capillaries. Oxygen diffuses from the alveolar air into the blood, while carbon dioxide diffuses from the blood into the alveolar air. The lungs contain approximately 300 million alveoli, providing a massive surface area (~70 m²) for gas exchange.

Question 17

The human nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS). Which of the following correctly describes the composition of the CNS?

Accepted Answer

The central nervous system (CNS) consists of the brain and spinal cord. The brain is the command center containing approximately 86 billion neurons and is divided into the cerebrum, cerebellum, and brainstem. The spinal cord is a column of neural tissue extending from the medulla oblongata to the lumbar region, serving as the main pathway for communication between the brain and the rest of the body. Together, the brain and spinal cord process sensory information and coordinate motor responses.

Question 18

Which of the following hormones is produced by the pancreas and plays a crucial role in regulating blood glucose levels by facilitating the uptake of glucose into cells?

Accepted Answer

Insulin is a peptide hormone secreted by beta cells (β-cells) of the islets of Langerhans in the pancreas. It lowers blood glucose by promoting glucose uptake into muscle, fat, and liver cells, and stimulates glycogen synthesis. Deficiency or dysfunction of insulin leads to diabetes mellitus.

SSC GD Constable Biology — Human Body

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60-Second Revision — Biology — Human Body