All Free Biology MCQs with Answers

1951. Pepsinogen is produced from__________?

• A. Mucous cells
• B. Parietal cells
• C. Zymogen cells
• D. All of these

Explanation: Pepsinogen is an inactive digestive enzyme released by zymogen, or chief, cells in the gastric glands. Parietal cells secrete hydrochloric acid, while mucous cells produce protective mucus, so students commonly choose parietal cells by confusing all gastric gland secretions.

1952. Hunger pangs usually begin ______ after the previous meal.

• A. 2-4 hours
• B. 6-8 hours
• C. 10-12 hours
• D. 12-24 hours

Explanation: Hunger pangs are rhythmic stomach contractions that commonly become noticeable about 12 to 24 hours after the previous meal, especially when the stomach is empty. The likely alternative is 2 to 4 hours, which confuses the time of early digestion and gastric emptying with the usual interval before strong hunger contractions.

1953. Secretin inhibits production of__________________?

• A. Gastric juice
• B. Pancreatic juice
• C. Bile
• D. All of these

Explanation: Secretin is released by the duodenum when acidic chyme enters it, and it reduces gastric activity while promoting pancreatic bicarbonate secretion. This helps neutralise acid in the small intestine. The likely distractor is pancreatic juice because secretin affects the pancreas, but it stimulates bicarbonate-rich pancreatic secretion rather than inhibiting it.

1954. Enterobius vermicularis is commonly known as____________?

• A. Flatworm
• B. Pinworm
• C. Hook worm
• D. Tapeworm

Explanation: Enterobius vermicularis is the intestinal nematode commonly called the pinworm or threadworm. It is a roundworm, not a flatworm, tapeworm or hookworm, so students may choose d because both pinworms and tapeworms are intestinal parasites.

1955. Salivary glands present in front of ear are___________?

• A. Sublingual
• B. Submaxillary
• C. Submandibular
• D. Parotid

Explanation: The parotid glands lie on the sides of the face, just in front of and below each ear, and release saliva through Stensen's ducts. Students often choose sublingual glands because they are also salivary glands, but sublingual glands lie beneath the tongue.

1956. Initial pH of food vacuole during digestion in amoeba is____________?

• A. 5.3
• B. 5.6
• C. 7.3
• D. 7.6Standardized & Admissions Tests

Explanation: The newly formed food vacuole in Amoeba is commonly described as having an initially acidic pH of about 5.6, which supports the activity of digestive enzymes. Students may choose 7.3 because they confuse the food vacuole with the approximately neutral pH of the surrounding cytoplasm.

1957. If bile pigments are prevented from leaving digestive tract, then they cause_____________?

• A. Hepatitis
• B. Jaundice
• C. Gall stones
• D. Blockage

Explanation: Bile pigments normally leave the body with the faeces, but their accumulation in blood and tissues produces the yellow discoloration called jaundice. Students may choose gall stones because both conditions can involve bile flow, but gall stones are solid deposits rather than the effect of retained pigments itself.

1958. From right ventricle blood is pushed into?

• A. pulmonary trunk
• B. brain
• C. aorta
• D. body

Explanation: The right ventricle pumps deoxygenated blood through the pulmonary semilunar valve into the pulmonary trunk, which divides into the pulmonary arteries leading to the lungs. Students may choose the aorta because it is another major artery leaving a ventricle, but the aorta receives blood from the left ventricle. Therefore, option a is correct.

1959. The heart is enclosed in a membrane called________?

• A. pleura
• B. pericardium
• C. peritoneum
• D. epithelium

Explanation: The pericardium is the double-layered membranous sac surrounding the heart and contains lubricating fluid that reduces friction during beating. The pleura surrounds the lungs, so it is the most likely alternative students choose by confusing the membranes of nearby thoracic organs.

1960. Average of heart beat of Adult Human?

• A. 60 to 100
• B. 70 to 100
• C. 50 to 100
• D. 80 to 100

Explanation: A normal resting adult human heart rate is generally about 60 to 100 beats per minute, reflecting the rate at which the sinoatrial node generates impulses. Students may choose 70 to 100 beats per minute because about 72 beats per minute is a common average, but the accepted normal range begins at 60 beats per minute.