All Free Biology MCQs with Answers

1191. The sponges in which sperms develop first are included in the category of__________?

• A. Peritandrous
• B. Pertandrous
• C. Protendrous
• D. Protandrous

Explanation: Protandrous sponges produce functional sperm before eggs, reducing the chance of self-fertilization and encouraging cross-fertilization. The word protandrous refers specifically to male function appearing first. Students may choose c because it looks like a spelling variant, but the accepted term is protandrous.

1192. A sponge of Antarctica which is more than a meter tall is____________?

• A. Scolymastra joubini
• B. Euplectella
• C. Spongilla
• D. Leucoselenia

Explanation: Scolymastra joubini is a giant Antarctic sponge reported to grow more than one metre tall. Euplectella is the well-known Venus flower-basket, Spongilla is a freshwater sponge, and Leucosolenia is a small calcareous sponge. The likely trap is b because Euplectella is a famous large sponge, but it is not the Antarctic species named here.

1193. The function of coelom is__________?

• A. To increase the size of the animals
• B. To help in the functioning of reproductive system
• C. To provide space for the development of organs and systems
• D. None of these

Explanation: The coelom provides a fluid-filled space in which internal organs and organ systems can develop, move, and function without being tightly compressed against the body wall. It can also support circulation and organ suspension, but merely increasing body size is not its defining function. Students may choose b because reproductive organs can occupy the coelom, but the function is broader than reproduction.

1194. In most triploblasts after embryonic development the three layers are represented as___________?

• A. Separate layers of cells
• B. Structures formed from them
• C. Structures associated with them
• D. Their functions in body

Explanation: During development, ectoderm, mesoderm and endoderm do not usually remain as simple separate sheets; they differentiate into organs and tissues such as skin, muscles, bones and the gut. Students may choose a because the germ layers begin as separate cell layers, but that describes their embryonic arrangement rather than their adult representation.

1195. Of the following which one is not found in series proterostomia?

• A. Annelida
• B. Arthropoda
• C. Mollusea
• D. Echinodermata

Explanation: Annelids, arthropods and molluscs are protostomes, whereas echinoderms are deuterostomes. The common trap is molluscs, but their blastopore generally develops into the mouth, which is a protostome characteristic.

1196. Coelom that develops from the archenteron as outpouching is__________?

• A. Pseudocoelom
• B. Enterocoelom
• C. Schizocoelom
• D. None of these

Explanation: In an enterocoelom, the coelom forms as pouches that bud outward from the archenteron, the primitive gut. Students often choose c because schizocoelom is also a true coelom, but it forms by splitting within mesoderm rather than by archenteron outpouching.

1197. Of the following which one is not included in Proterostomes?

• A. Arthropods
• B. Hemichordates
• C. Annelids
• D. Molluses

Explanation: Arthropods, annelids and molluscs are protostomes, while hemichordates are generally grouped with deuterostomes. The likely mistake is choosing arthropods because their body plan is highly specialized, but their developmental pattern is still protostomous.

1198. Inner layers of the sponges are made up of__________?

• A. Pinacocytes
• B. Choanoderm
• C. Choanoytes
• D. Pinacoderm

Explanation: The inner lining of a sponge is the choanoderm, and it is made of flagellated collar cells called choanocytes that create water currents and trap food. Students may choose b because choanoderm is the name of the layer, but the question asks for the cells forming it.

1199. Sperms are _________ in origin.

• A. Ectodermal
• B. Mesodermal
• C. Endodermal
• D. None of these

Explanation: Sperm develop from germ cells associated with the reproductive organs, which are derived from mesoderm in the traditional germ-layer classification. Students may choose a because sperm are released from an epithelial lining, but the surface epithelium is not their developmental germ-layer origin.

1200. Gut in pseudocoelomates is made from___________?

• A. Ectoderm
• B. Mesoderm
• C. Endoderm
• D. All of these

Explanation: The epithelial lining of the gut develops from endoderm, even in pseudocoelomates, whose body cavity is not completely lined by mesoderm. Students may choose b because mesoderm forms much of the body wall and muscles, but it does not form the gut lining.