All Free Biology MCQs with Answers

1211. The animals in which coelom is formed due to splitting of mesocerm are known as____________?

• A. Pseudocoelous
• B. Schizocoelous
• C. Enterocoelous
• D. Emphicoelous

Explanation: In schizocoelous development, the coelom forms by splitting of solid masses of mesoderm. Enterocoelous coelom formation occurs when pouches bud from the embryonic gut, so students may select enterocoelous if they confuse the two methods.

1212. Of the following which one is not the characteristic of triploblasts?

• A. All of them have blood vascular system
• B. They may be coelomate pseudocoelomate or acoelomate
• C. They are included in grade bilaterian
• D. All of them have digestive system

Explanation: Triploblasts possess ectoderm, mesoderm and endoderm, but not all have a blood vascular system because simple triploblastic animals can transport materials by diffusion. They may be acoelomates, pseudocoelomates or coelomates and generally have a digestive system, so students may incorrectly reject option d by overlooking simple or incomplete digestive systems.

1213. Both radial and bilateral symmetry is found in the phylum____________?

• A. Protozoa
• B. Porifera
• C. Echinodermata
• D. None of these

Explanation: Echinoderms have bilateral symmetry in their larval stage but generally radial, specifically pentaradial, symmetry as adults. Students may choose Porifera because some sponges show radial organisation, but sponges are commonly asymmetrical and do not characteristically show this clear larval-adult change.

1214. The radial symmetry is found in the animals of___________?

• A. Protozoa
• B. Porifera
• C. Cnidaria
• D. All of these

Explanation: Cnidarians such as Hydra, jellyfish and sea anemones have body parts arranged around a central oral-aboral axis, producing radial symmetry. Students may choose all of these because some protozoans and sponges can show radial forms, but radial symmetry is the standard characteristic of Cnidaria in this classification.

1215. All of the following are coelomates except:____________?

• A. Deuterosomes
• B. Proterosomes
• C. Hemichordates
• D. Aschelminthes

Explanation: Aschelminthes, including roundworms, are pseudocoelomates because their body cavity is not completely lined by mesoderm. Deuterostomes, protostomes and hemichordates are treated as coelomate groups, so students may choose protostomes if they mistake the developmental grouping for a non-coelomate condition.

1216. The greatest diversity of animals in the lake is found in which one of the following zones?

• A. Limmnetic zone
• B. Littoral zone
• C. Profundal zone
• D. None of these

Explanation: The littoral zone is the shallow, well-lit region near a lake shore, where light, oxygen, nutrients and varied habitats support many organisms. The limnetic zone is open water and usually has less habitat diversity. Students may choose the limnetic zone because it occupies a larger visible area, but the greatest animal diversity is generally at the shore.

1217. The unicellular organisms ingest large molecules into their cytoplasm from the external environment without previously digesting them. This process is called___________?

• A. Diffusion
• B. Osmosis
• C. Phagocytosis
• D. Plasmolysis

Explanation: Phagocytosis is the engulfment of large solid particles or molecules by extensions of the cell membrane, forming an internal vesicle for digestion. Students may choose diffusion because it also moves substances across membranes, but diffusion does not engulf large particles and requires no vesicle formation.

1218. Which of the statement about cell membrane is not true?

• A. It contains protein molecules embedded in lipid bilayer
• B. It is a differentially permeable membrane.
• C. It contains charged pores thus ions being charged particles cross cell membrance much easier than neutral particles.
• D. It may get infolded to engulf solid or liquid material.

Explanation: The membrane is selectively permeable, contains embedded proteins, and can fold inward during endocytosis to engulf material. Statement c is false because ions generally cannot pass through the lipid bilayer easily; they require specific protein channels, whereas some small neutral molecules cross more readily. Students may choose b by confusing selective permeability with complete impermeability.

1219. Yellow cytoplasm in ascidian gives rise to______________?

• A. Epidermis
• B. Muscle cells
• C. Gut
• D. Notochord

Explanation: In ascidian embryos, the yellow cytoplasmic region contains determinants that direct cells to develop into muscle tissue. These cytoplasmic factors influence gene expression during early embryonic development. Epidermis is a likely distractor because it is also an ectodermal body tissue, but it does not arise from the yellow muscle-forming cytoplasm.

1220. Far-red light promotes flowering in_______________?

• A. Short day plant
• B. Long day plant
• C. Day neutral plant
• D. None of these

Explanation: Far-red light converts the active Pfr form of phytochrome into the Pr form, which favours flowering in short-day plants by making the plant respond as though the uninterrupted night is longer. In long-day plants, red light generally promotes the flowering response by producing more Pfr. The common mistake is choosing long-day plant because far-red light is linked with changes in day length, without considering the phytochrome response.