Free Biodiversity and Variety of Life MCQs with Answers

3021. Placoid scales are present in:

• A. Class cyclostomata
• B. Class osteichthyes
• C. Class chondricthyes
• D. Ceplialochordate

Explanation: Placoid scales are a unique type of scales that are present in cartilaginous fishes like sharks and rays. These scales have a characteristic tooth-like structure with a hard enamel-like surface. They are embedded in the skin and provide protection and reduce drag in the water. The presence of placoid scales is one of the distinguishing features of the class Chondrichthyes, which includes sharks, rays, and skates.

3022. The giezard is used for crushing food in:

• A. Crocodile
• B. Frog
• C. Tiger
• D. Pigeon

Explanation: In the case of a pigeon, the gizzard is the part of their digestive system that helps with crushing and grinding food. Pigeons don't have teeth, so the gizzard, which is a muscular organ, contracts and uses small stones or grit to break down the food they eat. This process helps them extract as many nutrients as possible from their food. So, the gizzard in a pigeon is like a natural food processor.

3023. Trichonympha lies in the digestive tract of _ which produces an enzyme that helps in the digestion of wood:

• A. Cattle
• B. Tumefaciens
• C. Human
• D. Termite

Explanation: Trichonympha is a tiny organism that lives inside the digestive tract of termites. It's like a little helper for termites because it produces special enzymes called cellulases. These enzymes are super important because they help termites break down and digest wood, which is their main source of food.

3024. The amazing example of genetic and environmental influence on animal behavior is:

• A. Habituation
• B. Imprinting
• C. Operant learning
• D. Insight learning

Explanation: Imprinting is a behavior in which a young animal forms an attachment to another organism or object during a critical period early in life. It demonstrates a clear interaction between genetic predispositions and environmental influences. For example, the classic example is the imprinting of ducklings on their mother shortly after hatching.

3025. Hag fish belongs To:

• A. Cartilaginous fishes
• B. Bony fishes
• C. Cyclostomes
• D. Both (A) & (B)

Explanation: Hagfish, also known as cyclostomes, are a type of jawless fish. They have a unique anatomy and behavior compared to cartilaginous fishes like sharks and rays. Hagfish are known for their slimy secretion and their ability to produce copious amounts of mucus as a defense mechanism. They play an important role in marine ecosystems.

3026. The largest phylum of animals is:

• A. Annelida
• B. Arthropoda
• C. Chordata
• D. Coelenterata

Explanation: The largest phylum of animals is the phylum Arthropoda. It includes insects, spiders, crustaceans, and other joint-legged organisms. Arthropods are incredibly diverse and can be found in various habitats around the world.

3027. _ is found in the exoskeleton of crabs

• A. cellulose
• B. chitin
• C. murein
• D. hemi-cellulose

Explanation: Option B is correct. Chitin is found in the exoskeleton of crabs. Chitin is a tough, fibrous material that is made up of long chains of sugar molecules. It is the main component of the exoskeletons of insects, spiders, crabs, and other invertebrates. Chitin is also found in the cell walls of fungi and some algae. The other options are not found in the exoskeleton of crabs: Cellulose is a tough, fibrous material that is made up of long chains of sugar molecules. It is the main component of the cell walls of plants. Murein is a polymer made up of two sugar molecules and a short peptide chain. It is the main component of the cell walls of bacteria. Hemicellulose is a polymer of sugar molecules that is found in the cell walls of plants.

3028. Cup_like ascocarp in fungi is:

• A. Apothecium
• B. Perithecium
• C. Hysterothylacium
• D. Cleistothecium

Explanation: The correct answer is Apothecium. An apothecium is a cup-shaped ascocarp with an exposed hymenium. This structure fits the description of a cup-like ascocarp in fungi, making it the correct choice. Perithecium, Hysterothylacium, and Cleistothecium are all different types of ascocarps, but they do not match the specific cup-like morphology mentioned in the question.

3029. Early blight of potato is caused by:

• A. Alternaria_solani
• B. Phytophthora_infestans
• C. Erysiphe_graminls
• D. Claviceps_purpurea

Explanation: Alternaria solani is the correct answer as it is the fungal pathogen responsible for early blight of potato, causing specific symptoms on potato plants. The other options, such as Phytophthora infestans, Erysiphe graminis, and Claviceps purpurea, are pathogens that affect different plants and do not cause early blight in potatoes.

3030. Microsporum furfur causes:

• A. Athletes foot
• B. Ringworm
• C. Dandruff
• D. Ergot

Explanation: Microsporum furfur is a type of fungus that is associated with the condition known as dandruff. Dandruff is a common scalp disorder characterized by the shedding of dead skin cells from the scalp, resulting in visible flakes.