Free Biodiversity and Variety of Life MCQs with Answers

2991. Round worms, which have body cavities that are partially lined with mesoderm, are classified as:

• A. Acaelomate
• B. ceolomates
• C. Pseudocoelomates
• D. Deuterostomes

Explanation: A pseudocoelomate is an organism with a body cavity called a pseudocoelem that is not derived from the mesoderm, as in a true coelom, or body cavity. In invertebrates, the pseudocoelom is filled with fluid that lies between the mesoderm layer of the external body wall and the endoderm layer of the gut. But this is not a true coelem as it originates from the blastocoel, not the archenteron of Gastrula, which is the true site of origin of coelem. Roundworms in the phylum Aschelminthes are pseudocoelemates.

2992. Crustaceans are the only arthropods that have:

• A. chitin in their exoskeleton
• B. chlicitae
• C. three pairs of legs
• D. two pairs of antennae

Explanation: Crustaceans are the only arthropods with two pairs of antennae, so option D is correct. All arthropods have chitin in their exoskeleton. Chelicerae are mouth parts present in some arthropods like arachnids, horseshoe crabs, and sea spiders, but they are absent in crustaceans. Crustaceans have five pairs of legs, not three.

2993. In spiders, the organs that contain the silk glands are called

• A. spinneret
• B. Carapace
• C. Medriporite
• D. Tube feet

Explanation: Spiders, which belong to the phylum Arthropoda, are predators who trap their prey by producing silk threads. The spinneret is the silk-producing organ in spiders.

2994. Which of the following bird structures are especially adapted to support flight?

• A. Cloacas
• B. Bills
• C. Gizzard
• D. chest muscles

Explanation: The shape of the sternum and chest muscles aid birds in flight.

2995. Which of the following is NOT an innate behavior?

• A. A mammal sucking milk
• B. A dog looking for its food dish
• C. A worm moving away from bright light
• D. A spider spinning a web

Explanation: The correct answer is Option B: 'A dog looking for its food dish.' This behavior is learned because dogs associate the dish with food through experience. In contrast, the other behaviors listed are innate, meaning they are instinctive and do not require learning or experience. A mammal sucking milk, a worm moving away from bright light, and a spider spinning a web are all actions that animals perform without prior learning, driven by instinctual responses.

2996. Spiders belong to class:

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

Explanation: Spiders belong to the class Arachnida, which includes joint-legged animals like scorpions, ticks, and mites. Arachnids are distinct from other arthropods due to their eight-legged structure, lack of antennae, and body divided into two main segments. Unlike crustaceans, arachnids are not primarily aquatic. They also differ from myriapods, which have many body segments and legs, and from hexapods (insects), which have six legs and three body segments.

2997. Lobsters belong to class:

• A. Myriapoda
• B. Arychnida
• C. Hexapoda
• D. Crustacean

Explanation: Crustaceans form a very large group of arthropods, which includes crabs, lobsters, crayfish etc. They are distinguished from other groups, like insects by possession of biramous limbs an the nauplius form of the larvae. Hence the answer is D.

2998. The gills are covered by operculum in

• A. Bony fishes
• B. Cartllaginous fishes
• C. Lung fishes
• D. Jawless fishes

Explanation: The operculum is a hard, plate-like bony flap that covers the gills of a bony fish protecting the gills and also serves a role in respiration. Hence the answer will be A.

2999. Which one of the following animals is filter feeder?

• A. Teeth
• B. Sycon
• C. Fresh water mussels
• D. Jelly fish

Explanation: Sycon are sponges that receive food particles with the help of collar cells, therefore are called filter feeders.

3000. Which one of the following animals is viviparous?

• A. Rat
• B. Kangaroo
• C. Duckbilled platypus
• D. Spiny ant eater

Explanation: Viviparous species are those who give birth to living young ones directly instead of laying eggs. Rats are viviparous, therefore the correct answer will be A.