Question 1

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 2

Vitamin D is primarily synthesized in the human body with the help of:

Accepted Answer

Vitamin D is synthesized in the skin when it is exposed to ultraviolet B (UVB) radiation from sunlight. The liver and kidneys then convert it to its active form (calcitriol), which regulates calcium absorption.

Question 3

Which of the following hormones is responsible for regulating blood glucose levels in the human body?

Accepted Answer

Insulin, secreted by beta cells of the pancreatic islets of Langerhans, lowers blood glucose by promoting glucose uptake into cells. Glucagon, secreted by alpha cells, raises blood glucose. Together they maintain homeostasis.

Question 4

Which of the following vitamins is fat-soluble and is essential for blood clotting?

Accepted Answer

Vitamin K is a fat-soluble vitamin required for the synthesis of prothrombin and other clotting factors (II, VII, IX, X) by the liver. It is produced by gut bacteria and obtained from leafy green vegetables.

Question 5

The structural and functional unit of the kidney responsible for filtration of blood is called:

Accepted Answer

The nephron is the functional unit of the kidney. Each kidney contains approximately 1 million nephrons. Each nephron consists of a renal corpuscle (glomerulus + Bowman's capsule) and a renal tubule, which together filter blood and produce urine.

Question 6

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

Accepted Answer

Vitamin D is synthesized by the human body when skin is exposed to sunlight (UV-B radiation). The skin converts 7-dehydrocholesterol into previtamin D3, which is then converted to active vitamin D in the liver and kidneys. While dietary sources (fatty fish, fortified milk, egg yolks) contribute to vitamin D intake, the body can produce significant amounts endogenously, unlike vitamins A, B12, and C which must be obtained from food sources.

Question 7

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 process converts 7-dehydrocholesterol in the skin to previtamin D3, which is then converted to active vitamin D. This is why vitamin D is sometimes called the 'sunshine vitamin.'

Question 8

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 pancreatic islets (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 CPO level.

Question 9

Which disease is caused by the deficiency of Vitamin B12 in the human body?

Accepted Answer

Vitamin B12 (cobalamin) deficiency causes pernicious anemia, a type of megaloblastic anemia characterized by the production of large, immature red blood cells. This occurs because B12 is essential for DNA synthesis and red blood cell maturation. B12 deficiency can result from dietary insufficiency (especially in vegans), malabsorption, or lack of intrinsic factor.

Question 10

Which of the following is NOT a function of the liver?

Accepted Answer

The liver performs multiple vital functions including synthesis of plasma proteins, detoxification, bile production, glycogen storage, and metabolism of nutrients. However, the liver does NOT produce insulin (pancreas does), does NOT produce thyroid hormones (thyroid gland does), and does NOT produce antibodies (B lymphocytes do).

Question 11

The hormone insulin is produced by which part of the pancreas?

Accepted Answer

Insulin is produced by beta cells (β-cells) located in the islets of Langerhans, which are clusters of endocrine cells in the pancreas. The islets of Langerhans contain three main cell types: alpha cells (produce glucagon), beta cells (produce insulin), and delta cells (produce somatostatin).

Question 12

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

Accepted Answer

The blood flow through the heart follows a specific pathway: deoxygenated blood enters the right atrium via superior and inferior vena cava → flows to right ventricle → pumped to lungs via pulmonary artery → oxygenated blood returns via pulmonary veins to left atrium → flows to left ventricle → pumped to body via aorta.

Question 13

Which of the following hormones is produced by the pancreas and regulates blood glucose levels by facilitating glucose uptake into cells?

Accepted Answer

Insulin is a peptide hormone secreted by beta cells of the islets of Langerhans in the pancreas. It lowers blood glucose by promoting glucose uptake, glycogen synthesis, and lipid storage in target tissues. Glucagon raises blood glucose; thyroxine regulates metabolism; and cortisol is a stress hormone from the adrenal cortex.

Question 14

Which of the following statements about the human pancreas is INCORRECT?

Accepted Answer

The pancreas is a dual-function organ. It acts as an endocrine gland (producing hormones like insulin and glucagon) and an exocrine gland (producing digestive enzymes). Insulin is produced by beta cells in the islets of Langerhans and regulates blood glucose by promoting uptake into cells. The pancreas produces multiple digestive enzymes including amylase, lipase, and proteases, not just one. It is located behind the stomach in the retroperitoneal space.

Question 15

The human kidney filters waste products from blood to form urine. Which of the following is the functional filtration unit of the kidney?

Accepted Answer

The nephron is the basic structural and functional unit of the kidney responsible for filtration, reabsorption, and secretion. Each kidney contains approximately 1 million nephrons. A nephron consists of the renal corpuscle (glomerulus + Bowman's capsule) and the renal tubule (proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct).

Question 16

Which vitamin is synthesized by the human body when skin is exposed to sunlight and is essential for calcium absorption and bone health?

Accepted Answer

Vitamin D is a fat-soluble vitamin synthesized in the skin upon exposure to ultraviolet B (UVB) radiation from sunlight. It is converted to its active form (calcitriol) in the kidneys and plays a crucial role in calcium and phosphate homeostasis, bone mineralization, and immune function. Deficiency leads to rickets in children and osteomalacia in adults.

Question 17

In the human respiratory system, gas exchange occurs in the alveoli. Which of the following statements about alveolar structure is correct?

Accepted Answer

Alveoli are tiny air sacs in the lungs where gas exchange occurs. They are lined with a simple squamous epithelium that is extremely thin (approximately 0.5 micrometers), allowing efficient diffusion of oxygen and carbon dioxide. Alveoli are surrounded by a rich network of pulmonary capillaries. The alveolar wall also contains surfactant-producing cells (Type II pneumocytes) that reduce surface tension and prevent alveolar collapse.

Question 18

The human immune system has two main branches: innate and adaptive immunity. Which of the following is a characteristic feature that distinguishes adaptive immunity from innate immunity?

Accepted Answer

Adaptive immunity is characterized by specificity, memory, and the ability to recognize and respond to specific antigens. It involves lymphocytes (T cells and B cells) and produces antibodies. In contrast, innate immunity is non-specific, provides immediate response, and has no memory component. Adaptive immunity develops over time and improves upon repeated exposure to the same pathogen (immunological memory).

SSC CPO Biology — Human Body

Biology — Human Body— Rules & Concept

Key Points to Remember

Exam-Specific Tips

Biology — Human Body — Practice Questions

60-Second Revision — Biology — Human Body