- Which organ in the human body is primarily responsible for filtering urea from the blood?
A) Liver
B) Kidney
C) Spleen
D) Pancreas
Correct Answer: B) Kidney
Explanation: The kidneys filter urea and other nitrogenous wastes from the blood, forming urine. The liver produces urea from ammonia, but excretion is performed by the kidneys. - What is the main function of the human trachea?
A) Absorb oxygen
B) Transport air to the lungs
C) Filter blood
D) Produce sound
Correct Answer: B) Transport air to the lungs
Explanation: The trachea (windpipe) is a tube that carries inhaled air from the throat to the bronchi and into the lungs for gas exchange. - Which plant hormone is responsible for promoting cell division?
A) Ethylene
B) Cytokinin
C) Abscisic acid
D) Gibberellin
Correct Answer: B) Cytokinin
Explanation: Cytokinins stimulate cell division and growth, especially in plant roots and shoots. Ethylene promotes ripening, abscisic acid induces dormancy, and gibberellin promotes stem elongation. - Which structure in the human digestive system prevents food from entering the windpipe?
A) Larynx
B) Epiglottis
C) Pharynx
D) Trachea
Correct Answer: B) Epiglottis
Explanation: The epiglottis is a flap of cartilage that closes over the trachea during swallowing, preventing food from entering the airway. - What is the primary function of mitochondria in animal cells?
A) Protein synthesis
B) Energy production
C) Lipid storage
D) Waste removal
Correct Answer: B) Energy production
Explanation: Mitochondria are the site of aerobic respiration, converting glucose and oxygen into ATP, the cell’s main energy currency. - Which vitamin deficiency causes pellagra?
A) Vitamin B1
B) Vitamin B3
C) Vitamin B6
D) Vitamin B12
Correct Answer: B) Vitamin B3
Explanation: Pellagra is caused by a deficiency of niacin (vitamin B3), leading to dermatitis, diarrhea, and dementia. - What is the role of the human alveoli?
A) Absorb nutrients
B) Exchange gases
C) Filter blood
D) Store oxygen
Correct Answer: B) Exchange gases
Explanation: Alveoli are tiny sacs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses out during respiration. - Which element is essential for the synthesis of chlorophyll in plants?
A) Iron
B) Magnesium
C) Potassium
D) Sodium
Correct Answer: B) Magnesium
Explanation: Magnesium is the central atom in the chlorophyll molecule and is necessary for photosynthesis in plants. - Which blood component transports carbon dioxide mainly as bicarbonate ions?
A) Plasma
B) Red blood cells
C) Platelets
D) White blood cells
Correct Answer: A) Plasma
Explanation: Most carbon dioxide is transported in the blood as bicarbonate ions dissolved in the plasma, with a smaller portion carried by red blood cells. - Which organ is responsible for producing digestive enzymes and hormones like insulin?
A) Liver
B) Pancreas
C) Gallbladder
D) Spleen
Correct Answer: B) Pancreas
Explanation: The pancreas produces digestive enzymes for the small intestine and hormones such as insulin and glucagon for blood sugar regulation. - Which process involves the movement of water through the plant from roots to leaves and out through the stomata?
A) Respiration
B) Transpiration
C) Photosynthesis
D) Translocation
Correct Answer: B) Transpiration
Explanation: Transpiration is the evaporation of water from plant leaves, creating a pull that moves water upward from the roots. - Which hormone is secreted by the thyroid gland to regulate metabolism?
A) Insulin
B) Thyroxine
C) Adrenaline
D) Glucagon
Correct Answer: B) Thyroxine
Explanation: Thyroxine (T4) is produced by the thyroid gland and regulates the body’s metabolic rate, growth, and development. - What is the function of the human gallbladder?
A) Produce bile
B) Store and concentrate bile
C) Digest proteins
D) Absorb nutrients
Correct Answer: B) Store and concentrate bile
Explanation: The gallbladder stores bile produced by the liver and releases it into the small intestine to help digest fats. - Which type of immunity is acquired by vaccination?
A) Innate immunity
B) Passive immunity
C) Active immunity
D) Natural immunity
Correct Answer: C) Active immunity
Explanation: Vaccination stimulates the body to produce its own antibodies and memory cells, providing long-term active immunity. - Which structure in the human heart pumps oxygenated blood to the body?
A) Right atrium
B) Right ventricle
C) Left atrium
D) Left ventricle
Correct Answer: D) Left ventricle
Explanation: The left ventricle pumps oxygen-rich blood into the aorta, distributing it throughout the body. - Which mineral is essential for the synthesis of hemoglobin?
A) Calcium
B) Iron
C) Zinc
D) Potassium
Correct Answer: B) Iron
Explanation: Iron is a key component of hemoglobin, the protein in red blood cells that binds and transports oxygen. - Which process describes the movement of food through the digestive tract by muscular contractions?
A) Digestion
B) Absorption
C) Peristalsis
D) Assimilation
Correct Answer: C) Peristalsis
Explanation: Peristalsis is the wave-like contraction of smooth muscles that moves food along the digestive tract. - Which vitamin is essential for the absorption of calcium from the intestine?
A) Vitamin A
B) Vitamin B12
C) Vitamin C
D) Vitamin D
Correct Answer: D) Vitamin D
Explanation: Vitamin D promotes the absorption of calcium from the intestine, which is vital for healthy bones and teeth. - Which blood vessel carries deoxygenated blood from the body to the heart?
A) Pulmonary vein
B) Aorta
C) Vena cava
D) Pulmonary artery
Correct Answer: C) Vena cava
Explanation: The vena cava (superior and inferior) carries deoxygenated blood from the body back to the right atrium of the heart. - Which hormone is responsible for stimulating uterine contractions during childbirth?
A) Estrogen
B) Progesterone
C) Prolactin
D) Oxytocin
Correct Answer: D) Oxytocin
Explanation: Oxytocin, released by the pituitary gland, stimulates powerful uterine contractions during labor and also aids milk ejection during breastfeeding. - Which organ in the human body is responsible for detoxifying drugs and alcohol?
A) Kidney
B) Liver
C) Pancreas
D) Spleen
Correct Answer: B) Liver
Explanation: The liver metabolizes and detoxifies drugs, alcohol, and other harmful substances, making them less toxic for excretion. - Which process produces ATP in the absence of oxygen?
A) Aerobic respiration
B) Anaerobic respiration
C) Photosynthesis
D) Chemosynthesis
Correct Answer: B) Anaerobic respiration
Explanation: Anaerobic respiration (fermentation) produces ATP without oxygen, but yields less energy than aerobic respiration. - Which part of the human skeleton protects the spinal cord?
A) Skull
B) Rib cage
C) Vertebral column
D) Pelvis
Correct Answer: C) Vertebral column
Explanation: The vertebral column (spine) surrounds and protects the spinal cord from injury. - Which enzyme breaks down proteins in the small intestine?
A) Amylase
B) Lipase
C) Trypsin
D) Maltase
Correct Answer: C) Trypsin
Explanation: Trypsin, produced by the pancreas, digests proteins into smaller peptides in the small intestine. - Which hormone controls the reabsorption of water in the kidneys?
A) Adrenaline
B) Insulin
C) Antidiuretic hormone
D) Thyroxine
Correct Answer: C) Antidiuretic hormone
Explanation: Antidiuretic hormone (ADH), produced by the pituitary gland, increases water reabsorption in the kidneys to maintain fluid balance. - Which process describes the transfer of genetic information from DNA to mRNA?
A) Translation
B) Transcription
C) Replication
D) Mutation
Correct Answer: B) Transcription
Explanation: Transcription is the process by which genetic information from DNA is copied into messenger RNA for protein synthesis. - Which vitamin deficiency causes beriberi?
A) Vitamin B1
B) Vitamin B2
C) Vitamin B6
D) Vitamin B12
Correct Answer: A) Vitamin B1
Explanation: Beriberi is caused by a deficiency of thiamine (vitamin B1), affecting the nervous and cardiovascular systems. - Which structure in the human eye changes shape to focus light?
A) Cornea
B) Lens
C) Iris
D) Retina
Correct Answer: B) Lens
Explanation: The lens is flexible and changes shape (accommodation) to focus light onto the retina for clear vision. - Which hormone stimulates the production of red blood cells?
A) Insulin
B) Erythropoietin
C) Glucagon
D) Thyroxine
Correct Answer: B) Erythropoietin
Explanation: Erythropoietin, produced by the kidneys, stimulates the bone marrow to produce more red blood cells in response to low oxygen levels. - Which disease is caused by a deficiency of vitamin C?
A) Rickets
B) Scurvy
C) Pellagra
D) Beriberi
Correct Answer: B) Scurvy
Explanation: Scurvy results from vitamin C deficiency, leading to bleeding gums, weak connective tissue, and poor wound healing. - Which part of the plant absorbs water and minerals from the soil?
A) Leaf
B) Stem
C) Root
D) Flower
Correct Answer: C) Root
Explanation: Roots anchor the plant and absorb water and minerals from the soil, supplying them to the rest of the plant. - Which enzyme breaks down starch into maltose?
A) Amylase
B) Lipase
C) Pepsin
D) Trypsin
Correct Answer: A) Amylase
Explanation: Amylase, found in saliva and pancreatic juice, breaks down starch into maltose, a disaccharide sugar. - Which mineral is essential for muscle contraction and nerve transmission?
A) Iron
B) Calcium
C) Magnesium
D) Zinc
Correct Answer: B) Calcium
Explanation: Calcium ions are crucial for muscle contraction, nerve impulse transmission, and blood clotting. - Which hormone regulates the basal metabolic rate in humans?
A) Insulin
B) Thyroxine
C) Adrenaline
D) Progesterone
Correct Answer: B) Thyroxine
Explanation: Thyroxine, produced by the thyroid gland, increases the basal metabolic rate, affecting how quickly the body uses energy. - Which process describes the fusion of male and female gametes?
A) Pollination
B) Fertilization
C) Germination
D) Implantation
Correct Answer: B) Fertilization
Explanation: Fertilization is the union of sperm and egg, resulting in the formation of a zygote. - Which structure in the human ear converts sound vibrations into nerve impulses?
A) Ossicles
B) Cochlea
C) Eardrum
D) Semicircular canals
Correct Answer: B) Cochlea
Explanation: The cochlea is a spiral-shaped organ that converts sound vibrations into electrical signals for the brain to interpret as sound. - Which vitamin is necessary for the synthesis of visual pigments in the retina?
A) Vitamin A
B) Vitamin B6
C) Vitamin C
D) Vitamin D
Correct Answer: A) Vitamin A
Explanation: Vitamin A is required for the production of rhodopsin, a pigment in the retina essential for vision in low light. - Which process describes the movement of water from an area of low solute concentration to high solute concentration through a membrane?
A) Osmosis
B) Diffusion
C) Active transport
D) Endocytosis
Correct Answer: A) Osmosis
Explanation: Osmosis is the passive movement of water across a semi-permeable membrane toward a higher solute concentration. - Which hormone is responsible for stimulating milk ejection during breastfeeding?
A) Oxytocin
B) Prolactin
C) Estrogen
D) Progesterone
Correct Answer: A) Oxytocin
Explanation: Oxytocin causes the muscles around the mammary glands to contract, ejecting milk during breastfeeding. - Which organ in the human body is responsible for producing bile?
A) Liver
B) Pancreas
C) Gallbladder
D) Spleen
Correct Answer: A) Liver
Explanation: The liver produces bile, which is important for the digestion and absorption of fats. - Which mineral is essential for the formation of thyroid hormones?
A) Calcium
B) Iron
C) Iodine
D) Magnesium
Correct Answer: C) Iodine
Explanation: Iodine is a key component of thyroid hormones (T3 and T4), necessary for regulating metabolism. - Which structure in the human body is responsible for the sense of smell?
A) Taste buds
B) Olfactory bulb
C) Cochlea
D) Retina
Correct Answer: B) Olfactory bulb
Explanation: The olfactory bulb receives signals from olfactory receptors in the nose and processes them as smells. - Which vitamin deficiency causes rickets in children?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
Correct Answer: C) Vitamin D
Explanation: Vitamin D deficiency impairs calcium absorption, leading to weak, soft bones in children—a condition known as rickets. - Which process describes the conversion of glucose into energy in the presence of oxygen?
A) Anaerobic respiration
B) Aerobic respiration
C) Photosynthesis
D) Fermentation
Correct Answer: B) Aerobic respiration
Explanation: Aerobic respiration uses oxygen to completely break down glucose, producing carbon dioxide, water, and a large amount of ATP. - Which hormone is responsible for regulating blood sugar by increasing glucose uptake by cells?
A) Glucagon
B) Insulin
C) Adrenaline
D) Thyroxine
Correct Answer: B) Insulin
Explanation: Insulin, secreted by the pancreas, lowers blood sugar by promoting glucose uptake by cells and storage as glycogen. - Which organ in the human body is responsible for filtering old red blood cells?
A) Liver
B) Kidney
C) Spleen
D) Pancreas
Correct Answer: C) Spleen
Explanation: The spleen filters and removes old or damaged red blood cells from circulation and helps fight infection. - Which process describes the movement of food from the mouth to the stomach?
A) Digestion
B) Absorption
C) Peristalsis
D) Assimilation
Correct Answer: C) Peristalsis
Explanation: Peristalsis is the rhythmic contraction of muscles in the esophagus that pushes food toward the stomach. - Which vitamin is essential for blood clotting?
A) Vitamin A
B) Vitamin C
C) Vitamin D
D) Vitamin K
Correct Answer: D) Vitamin K
Explanation: Vitamin K is necessary for the synthesis of clotting factors, preventing excessive bleeding. - Which part of the plant is responsible for photosynthesis?
A) Root
B) Stem
C) Leaf
D) Flower
Correct Answer: C) Leaf
Explanation: Leaves contain chloroplasts, where photosynthesis takes place, converting sunlight into chemical energy. - Which structure in the human brain controls voluntary muscle movements?
A) Medulla oblongata
B) Cerebellum
C) Cerebrum
D) Hypothalamus
Correct Answer: C) Cerebrum
Explanation: The cerebrum is responsible for voluntary muscle movements, reasoning, memory, and sensory perception.