Free Biodiversity and Variety of Life MCQs with Answers

781. Given below are four matchings of an animal and its kind of respiratory organ:

• A. (A) and (B)
• B. (A), (B) and (C)
• C. (B) and (D)
• D. (C) and (D).

Explanation: Silver fish is an insect in which respiration occurs by tracheae. These communicate with the exterior by paired apertures, called spiracles. The respiratory system of the scorpion consists of 4 pairs of book lungs that communicate with the outer air through stigma. In sea squirts, respiration occurs through pharyngeal slits. In dolphins, respiration occurs by lungs. Silver Fish and scorpion belong to phylum arthropoda while sea squirt and dolphins belong to phylum chordata.

782. In which of the following animals is the brain absent but nerve cells are present?

• A. Sponge
• B. Earthworm
• C. Cockroach
• D. Hydra

Explanation: Hydra belongs to the phylum coelenterata and has nerve cells but no brain. Its nervous system consists of nerve cells and their processes. Sensory cells are also present. Sponges do not have nerve cells as they lack a nervous system. Earthworm (annelida) has a nervous system consisting of a circumenteric nerve ring and a solid, double, midventral nerve cord with ganglia. Cockroach (arthropoda) has the same nervous system as the earthworm.

783. In which of the following is a notochord present in the embryonic stage?

• A. All chordates
• B. Some chordates
• C. Vertebrates
• D. Non chordates

Explanation: •Chordates are the animals that have a notochord, a skeletal rod, present at some stage in the life cycle. •In lower vertebrates, the notochord persists throughout life while in higher vertebrates it is replaced by vertebral column in adults. •Nonchordates never develop a notochord, not even in the embryonic stage.

784. In which of the following animals is the haemocyanin pigment found?

• A. Annelida
• B. Echinodermata
• C. Insecta
• D. Mollusca

Explanation: In molluscs, blood often has a copper containing, blue, respiratory pigment called haemocyanin. In insects, the blood called haemolymph is colourless. Blood is also colourless in echinodermates as it has no respiratory pigment. In annelids, the blood is red with haemoglobin dissolved in plasma.

785. In which of the following animals is a post anal tail found?

• A. Earthworm
• B. Lower invertebrates
• C. Scorpion
• D. Snake

Explanation: Snakes are limbless reptiles with an elongated cylindrical body that is covered with overlapping scales differentiated into shields and plates. They also have a long, post anal tail.

786. In Hydra waste material of food digestion and nitrogenous waste material are removed respectively from:

• A. Mouth and mouth
• B. Body wall and body wall
• C. Mouth and body wall
• D. Mouth and tentacles

Explanation: In Hydra, indigestible residues are egested through the mouth as there is no anus. Egestion occurs by a sudden squirt due to muscular contraction of body, so that the debris is thrown at a distance. Hydra has neither blood or blood vessels, nor organs of excretion. Due to thinness of the body wall and circulation of water in gastrovascular cavity, most cells of the body remain freely exposed to the surrounding water. Therefore, excretion of waste nitrogenous matter (chiefly ammonia) occurs directly by diffusion through cell membranes in the outside world.

787. Cleavage in mammals is:

• A. holoblastic equal
• B. holoblastic unequal
• C. superficial
• D. discoidal

Explanation: Cleavage in mammals is holoblastic unequal. Mammals have microlecithal eggs so they have holoblastic cleavage in which the segmentation lines pass through the entire egg, dividing it completely. As the eggs are microlecithal so one would expect that first cleavage will produce two equal blastomeres. But, this is not the case. The two blastomeres produced are unequal which divide further to form 4 unequal blastomeres and this process continues to form a ball of cells called morula. Superficial cleavage occurs in insects and discoidal cleavage occurs in birds.

788. Similarity in Ascaris lumbricoides and Anopheles stephensi is:

• A. Sexual dimorphism
• B. Metamerism .
• C. Anaerobic respiration
• D. Endoparasitism

Explanation: Sexual dimorphism refers to the difference in individuals of different sexes of the same species. Sexes in Ascaris are separate and sexual dimorphism is well defined. Males are smaller than females. They possess a recurved tail with pre and post anal papillae, a cloaca, and a pair of spicules or penial setae. In Anopheles, the ends of maxillary palps in males are club shaped while in females they are not.

789. What happens if bone of frog is kept in dilute hydrochloric acid?

• A. Will become flexible
• B. Will turn black
• C. Will break into pieces
• D. Will shrink

Explanation: Main component of bone is collagen which is a complex combination of amino acids. When frog's bone is treated with HCl, these compounds are broken down and the bone becomes flexible.

790. What is true for mammalia?

• A. Platypus is oviparous.
• B. Bats have feathers
• C. Elephants are ovoviviparous
• D. Diaphragm is absent

Explanation: Mammals are viviparous i.e., they give birth to young ones. Protherians (e.g., Platypus) are primitive mammals that lay eggs, so they are oviparous.