All Free Biology MCQs with Answers

1161. Which system is present in nematodes?

• A. Sac - like digestive system
• B. Tube - like digestive system
• C. Circulatory system
• D. Respiratory system

Explanation: Nematodes possess a complete, tube-like digestive system with a mouth, intestine and anus, allowing food to move in one direction. Students may choose a circulatory or respiratory system, but nematodes lack specialised systems for both functions and rely on diffusion.

1162. Pin warm is common name used for__________?

• A. Rhabditis
• B. Enterobius vermicularis
• C. Ancylostoma duodenale
• D. Taenia solium

Explanation: Enterobius vermicularis is the pinworm, also called the threadworm, and commonly infects the human intestine. Students may choose Ancylostoma because it is another intestinal roundworm, but Ancylostoma is the hookworm rather than the pinworm.

1163. True metamorphosis is not present in________?

• A. Crustacea
• B. Insecta
• C. Arachnida
• D. Myriapoda

Explanation: Arachnids generally develop directly, so the young resemble small adults and there is no true larval-to-adult metamorphosis. Students may choose Myriapoda because they also have relatively simple development, but true metamorphosis is especially associated with insects and some crustaceans.

1164. Prechordates is another name used for___________?

• A. Echinoderms
• B. Hemichordates
• C. Vertebrates
• D. Chordates

Explanation: Hemichordates are called prechordates because they show some chordate-like features but are considered an evolutionary group preceding true chordates. Students may choose echinoderms because both groups are deuterostomes, but echinoderms are not called prechordates.

1165. Mantle in molluscs is present over____________?

• A. Head
• B. Ventral muscular foot
• C. Dorsal visceral region
• D. All of these

Explanation: The molluscan mantle is a dorsal fold of the body wall that covers the visceral mass and usually forms the mantle cavity. Students may choose the muscular foot because it is another major molluscan structure, but the foot is ventral and is not covered by the mantle in the sense intended here.

1166. __________ are believed to have common origin with annelids.

• A. Nematods
• B. Arthropods
• C. Molluscs
• D. None of these

Explanation: Arthropods and annelids are traditionally considered to share a common segmented ancestor, since both show metamerism and similar developmental patterns in classical zoology. Students may choose molluscs because they are also invertebrates, but molluscs do not have the characteristic segmented body plan.

1167. Polychaeta have____________?

• A. Tentacles
• B. Palps
• C. Eyes
• D. All of these

Explanation: Polychaetes possess sensory and feeding structures such as tentacles and palps, and many species also have eyes. Students may choose only tentacles because they are the most obvious structures, but the listed features can all occur in polychaetes.

1168. Nervous system of nematods consists of?

• A. Ventral nerve cord
• B. Dorsal nerve cord
• C. Lateral nerve cord
• D. All of these

Explanation: The nematode nervous system includes a nerve ring and longitudinal dorsal, ventral and lateral nerve cords, so all three listed cords are present. Students may choose only the ventral cord because it is prominent, but the dorsal and lateral cords are also components of the system.

1169. All of the following are true for Platyhelminthes except____________?

• A. Flatwarms
• B. Triploblastic
• C. Coelomate
• D. Bilateral symmetry

Explanation: Platyhelminthes are triploblastic, bilaterally symmetrical flatworms, but they are acoelomate rather than coelomate because the space between the organs is filled with mesenchyme. Students may choose flatworms as the exception by treating the common name as informal, but it is a correct characteristic.

1170. Exoskeoeton of coelenterates terates is made up to__________?

• A. Calcium
• B. Silica
• C. Chitin
• D. Both A & B

Explanation: The hard exoskeleton of reef-building corals, which are coelenterates, is mainly calcium carbonate deposited by the animals. Students may choose silica because some aquatic organisms form siliceous skeletons, but silica is not the usual skeletal material of corals.