All Free Biology MCQs with Answers

1941. Of the following, which one is missing in herbivores_______________?

• A. Premolars
• B. Canines
• C. Incisors
• D. Molars.

Explanation: Typical herbivores lack prominent canines because their teeth are adapted mainly for cutting and grinding plant material, with incisors and molars being more important. The likely mistake is premolars, but premolars are present in many herbivores and assist the molars in grinding.

1942. Anus is surrounded by _____ types of muscles?

• A. 2
• B. 3
• C. 1
• D. 4

Explanation: The anus is controlled by two sphincters: an internal sphincter made of involuntary smooth muscle and an external sphincter made of voluntary skeletal muscle. The likely mistake is one, which ignores that the two sphincters have different muscle types and control mechanisms.

1943. The leaf is bilobed with midrib between them. The plant is____________?

• A. Saraccnia
• B. Dionaea
• C. Pitcher plant
• D. None of these

Explanation: Dionaea, the Venus flytrap, has a bilobed leaf with a midrib and trigger hairs; the two lobes close rapidly around an insect. The likely mistake is a pitcher plant, whose leaves form a tubular pitcher rather than two hinged lobes.

1944. Incomplete or imperfect digestion is known as________?

• A. Obesity
• B. Dyspepsia
• C. Anorexia nervous
• D. Bulimia nervosa

Explanation: Dyspepsia means indigestion and includes discomfort caused by incomplete or disturbed digestion. The likely mistake is anorexia nervosa, which is an eating disorder involving restricted food intake and body-image disturbance, not a digestive condition.

1945. Earthworm is an example of ______________feeder?

• A. Detritus
• B. Fluid
• C. Macrophageus
• D. Filter

Explanation: Earthworms ingest soil and feed on decaying organic matter, called detritus, so they are detritus feeders. A fluid feeder takes liquid nutrients, while a filter feeder strains suspended particles from water; students may choose macrophageus because earthworms ingest relatively large particles, but detritus is the specific feeding category.

1946. Loss of appetite due to the fear of becoming obese is____________?

• A. Anorexia nervosa
• B. Bulimia nervosa
• C. Piles
• D. Dyspepsia

Explanation: Anorexia nervosa is an eating disorder involving severe restriction of food intake and an intense fear of gaining weight or becoming obese. Bulimia nervosa instead involves repeated binge eating followed by compensatory behaviours, so students may choose bulimia because both are eating disorders.

1947. An illness which largely affects girls usually just after the onset of puberty.

• A. Bulimia nervosa
• B. Obesity
• C. Anorexia nervosa
• D. None of these

Explanation: Anorexia nervosa commonly begins around adolescence and is particularly frequent among girls, with restricted eating driven by fear of weight gain. Bulimia also affects adolescents, so students may choose it because it is another eating disorder, but the stem specifically describes anorexia's typical onset and restriction.

1948. Masses of dilated tortuous veins in the anorectal mucosa are known as___________?

• A. Bulimia
• B. Ulcer
• C. Adipose tissue
• D. Hemorrhoids

Explanation: Hemorrhoids are swollen or dilated tortuous veins in the anorectal region, often causing discomfort or bleeding. An ulcer is an open lesion rather than a mass of dilated veins, so students may choose ulcer because both can produce rectal bleeding.

1949. Mastication is carried out by__________?

• A. Teeth
• B. Tongue
• C. Smooth muscles
• D. All of these

Explanation: Mastication means mechanical chewing, in which the teeth cut, tear and grind food. The tongue helps position food, but smooth muscles do not perform chewing; students may choose all of these because they confuse chewing with later swallowing and gut movements.

1950. Dipeptides into amino acids are are converted through_____________?

• A. Amino peptidase
• B. Erypsin
• C. Pepsin
• D. Trypsin

Explanation: Erepsin is a mixture of intestinal peptidases that breaks dipeptides into amino acids at the intestinal surface. Pepsin acts mainly on proteins in the stomach and trypsin acts mainly on proteins or large peptides in the small intestine, so students may choose trypsin because it is also a pancreatic protein-digesting enzyme.