All Free Biology MCQs with Answers
Every Biology question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
19,844 questions · page 966 of 993
- A. 4.5
- B. 5.5
- C. 6.1 - 6.8
- D. 6.7 - 7
Explanation: Maltase is an enzyme that catalyzes the hydrolysis of the disaccharide maltose to the simple sugar glucose.
Correct answer: 6.1 - 6.8- A. Substrate concentration
- B. pH
- C. Enzyme concentration
- D. Temperaturep
Explanation: Substrate concentration refers to the amount of substrate present in a chemical reaction.
Correct answer: Substrate concentration- A. 3
- B. 3.5
- C. 2
- D. 2.5
Explanation: The stomach contains gastric glands that secrete hydrochloric acid (HCl) along with pepsinogen, an inactive precursor of pepsin.
Correct answer: 2- A. Sodium
- B. Potassium
- C. Bicarbonate
- D. Chloride
Explanation: The majority of carbon dioxide is transported as bicarbonate ions. This is because erythrocytes have a high activity of carbonic…
Correct answer: Bicarbonate- A. 2ml
- B. 3ml
- C. 4ml
- D. 5ml
Explanation: 6 mL of oxygen is delivered, at tissue level in normal conditions so option D is correct
Correct answer: 5ml- A. 10-30m
- B. 30-60m
- C. 70-90m
- D. 90-110m
Explanation: The alveoli form the gas exchange surface in the lungs, with about 700 million alveoli contributing to a total surface area of 70-90m2.
Correct answer: 70-90m19307. The alveoli is lined by:
- A. Cuboidal epithelium
- B. Squamous epithelium
- C. Columnar epithelium
- D. Transitional epithelium
Explanation: The alveoli, which are tiny air sacs in the lungs, are lined by a type of epithelium called squamous epithelium.
Correct answer: Squamous epithelium- A. Alveoli form the gas exchange surface
- B. The wall of each alveolus is 0.1 cm thick
- C. Alveoli has a dense network of capillaries
- D. Collagen and elastin present in alveoli allow it to expand and recoil easily during breathing
Explanation: Option B regarding alveoli is not correct.The walls of alveoli are extremely thin, only about 0.0002 cm thick.
Correct answer: The wall of each alveolus is 0.1 cm thick- A. Dominant genes
- B. Recessive genes
- C. Linked genes
- D. Autosomal genes
Explanation: When the two homozygous parents differing in two pairs of contrasting traits are crossed, the inheritance of one pair is independent of…
Correct answer: Linked genes- A. Amlyase
- B. Lipase
- C. Hydrochloric Acid
- D. Trypsin
Explanation: Pancreatic juice composition. Pancreatic juice is composed of water, mineral salts, enzymes, amylase, lipase, inactive enzyme precursors…
Correct answer: Hydrochloric Acid- A. Grasshoper and protozoa
- B. Grasshopper and frog
- C. Earthworm and protozoa
- D. Frog and protozoa
Explanation: Do you know what protozoans are? Yes, you do! They are single-cell organisms, just think if they are single-celled, why will they do…
Correct answer: Grasshopper and frog- A. Buccal chamber
- B. Intestine
- C. Rectum
- D. Intestinal caecum
Explanation: This needs a detailed analysis of the digestive system of earthworms.As this diagram shows esophagus opens into the intestine.
Correct answer: Intestine- A. Salivary gland
- B. Stomach
- C. Intestine
- D. Liver
Explanation: While bacteria are found in the mouth, they are not found within glands like the salivary gland. Therefore, A is incorrect.
Correct answer: Intestine- A. break down of cellulose
- B. synthesize some vitamins
- C. produce intestinal juice
- D. absorb water and mineral salts
Explanation: The large intestine is home to trillions of bacteria which are majorly involved in the production of vitamins (vit B1, B9, B7, B2, b5…
Correct answer: synthesize some vitamins- A. Canines
- B. Incisors
- C. Premolar
- D. Molar
Explanation: There are a total of 8 incisors found in both upper and lower jaws. Their primary function is to cut the food .There are two types of…
Correct answer: Incisors- A. Intestinal sac
- B. Typhlosole
- C. Oesophagus
- D. Pharyngeal mass
Explanation: The pharyngeal gland is made of chromophil cells, which produce saliva containing the proteolytic enzyme; protease, and mucin which…
Correct answer: Pharyngeal mass- A. Ptyalin
- B. Pepsin
- C. Diastase
- D. option missing
Explanation: Ptyalin aids in the digestion of starch in the mouth. Diastase breaks down starch into maltose in germinating seeds.
Correct answer: Ptyalin- A. Amylase
- B. Lipase
- C. Trypsinogen
- D. Insulin
Explanation: Option D is correct as pancreas is a heterocrine gland which also produces hormone named as insulin and glucagon which are produced by the…
Correct answer: Insulin- A. Liver
- B. Stomach
- C. Small intestine
- D. Large intestine
Explanation: Ammonia is formed during digestion in the large intestine, specifically the colon, through bacterial fermentation.
Correct answer: Large intestine- A. 1000ml/day
- B. 2000ml/day
- C. 3000ml/day
- D. 4000ml/day
Explanation: 1000ml/day: In a normal person, the liver produces between 800 to 1,000 milliliters of bile each day.
Correct answer: 1000ml/day