Free Human Body and Health MCQs with Answers

171. Which of the Following Hormones Regulate Blood Sodium and Potassium Levels in the Body?

• A. Aldosterone
• B. Cortisol
• C. Glycogens
• D. Pheromones

Explanation: Aldosterone, produced by the adrenal cortex, increases sodium reabsorption and promotes potassium excretion by the kidneys. Cortisol has different primary roles, while glycogen and pheromones are not hormones regulating these electrolytes.

172. Calcium level in the blood is regulated by the: ___________?

• A. Thyroid
• B. Parathyroid
• C. Adrenal medulla
• D. A and B

Explanation: Blood calcium is regulated mainly by parathyroid hormone and calcitonin, the latter produced by the thyroid gland. Therefore, both the thyroid and parathyroid are involved.

173. Which part of the brain controls the Pituitary Gland?

• A. Hindbrain
• B. Hypothalamus
• C. Hippocampus
• D. Midbrain

Explanation: The hypothalamus controls the pituitary through releasing and inhibiting hormones and also regulates its connection with the nervous system. The hippocampus is mainly involved in memory, not pituitary control.

174. The process which is essential for continuing and survival of species is __________?

• A. Digestion
• B. Respiration
• C. Reproduction
• D. Excretion

Explanation: Reproduction is essential for the continuation of a species because it produces new individuals. Digestion, respiration, and excretion sustain individual organisms but do not directly continue the species.

175. The part of brain involved in balance and precision in movements is: __________?

• A. Cerebrum
• B. Cerebellum
• C. Thalamus
• D. Medulla oblongata

Explanation: The cerebellum coordinates balance, posture, and the accuracy of voluntary movements. The cerebrum handles conscious thought and voluntary motor commands, but fine coordination is chiefly the cerebellum’s role.

176. What is the largest cell in the human body?

• A. Ovum
• B. RBCs
• C. Sperm cell
• D. Neuron

Explanation: The human ovum is the largest human cell by diameter, whereas a sperm cell is among the smallest. Red blood cells and neurons are not larger than the ovum in this standard comparison.

177. Chromosomes are made up of __________ ?

• A. DNA only
• B. DNA and RNA
• C. Proteins only
• D. DNA and Proteins

Explanation: Chromosomes consist of DNA wound around structural proteins called histones. DNA carries genetic information, while the proteins help package and organize it.

178. Cataract is a disease of ________?

• A. Eyes
• B. Throat
• C. Lungs
• D. Circulatory system

Explanation: A cataract is the clouding of the eye’s normally clear lens, which causes blurred or hazy vision. It is therefore an eye disorder, not a disease of the throat, lungs, or circulatory system.

179. Which bird weighs less than a penny?

• A. Goldcrest
• B. Weebill
• C. Hummingbird
• D. None of these

Explanation: The smallest hummingbirds, especially the bee hummingbird, weigh roughly 1.6 to 2 grams, less than a modern US penny weighing 2.5 grams. Goldcrests and weebills are generally heavier.

180. __________ Protect us from diseases?

• A. Vitamins
• B. minerals
• C. Carbohydrates
• D. None of these

Explanation: Vitamins support immune function and other protective body processes, so deficiencies can increase susceptibility to disease. Minerals are also essential, but this standard MCQ conventionally identifies vitamins as the protective nutrients.