Free Biodiversity and Variety of Life MCQs with Answers

721. In the biology laboratory, a student observed the following specimen.The identification and distinguishing feature of this specimen is:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: The figure shows a mussel. Its characteristic is bivalved shell.A mussel is an aquatic mollusk with a soft body protected by a hard, two-part (bivalved) shell. It usually lives in freshwater or marine environments and attaches itself to rocks or other surfaces.In contrast, a slug has a soft, elongated body with no shell So Option A correctly represents the figure.

722. Given is the classification of human and chimpanzee. The taxonomic categories in which humans and chimpanzee differ are:

• A. Order and Family
• B. Family and Genus
• C. Order and Species
• D. Genus and Species

Explanation: The correct answer is option D: genus and species. When classifying humans (Homo sapiens) and chimpanzee (Pan troglodytes), they belong to the different genus (Homo for humans and Pan for chimpanzee) and different species (sapiens and troglodytes). Genus and species represent the most specific levels of classification in the Linnaean system. The other options are incorrect because they either involve broader categories or incorrect combinations of taxonomic levels.

723. Which important characteristic do hemichordates share with chordates?

• A. Ventral tubular nerve cord
• B. Pharynx with gill slits
• C. Pharynx without gill slits
• D. Absence of notochord

Explanation: An important characteristic that hemichordates and chordates share is the presence of pharyngeal gill slits. Gill slits are dorsal in position in hemichordates whereas they are lateral in chordates. A true notochord does not occur in hemichordates. The nervous system is distinct from the vertebrate type being intraepidermal in position and having a ventral nerve cord.

724. Which among these is the correct combination of aquatic mammals?

• A. Dolphins, Seals, Trygon
• B. Whales, Dolphins, Seals
• C. Trygon, Whales, Seals
• D. Seals, Dolphins, Sharks

Explanation: Whales, dolphins, and seals are indeed mammals. They belong to a group of mammals known as marine mammals because they live in the water.

725. In case of poriferans, the spongocoel is lined with flagellated cells called:

• A. Oscula
• B. Choanocytes
• C. Mesenchymal cells
• D. Ostia

Explanation: Spongocoel is the central body cavity of the sponges. It is lined by highly specialised flagellated cells called choanocytes.

726. Which one of the following characteristics is not shared by birds and mammals?

• A. Viviparity
• B. Warm blooded nature
• C. Ossified endoskeleton
• D. Breathing using lungs

Explanation: All birds are oviparous while all mammals except Ornithorhyncus (duck billed platypus) and Echidna or Tachyglossus (spiny anteater) are viviparous.

727. Which of the following characteristic features always holds true for the corresponding group of animals?

• A. Possess a mouth with an upper and a lower jaw - Chordata
• B. 3-chambered heart with one incompletely divided ventricle - Reptilia
• C. Cartilaginous endoskeleton - Chondrichthyes
• D. Viviparous - Mammalia

Explanation: Chondrichthyes, a class of fish that includes sharks, rays, and chimaeras, have a cartilaginous endoskeleton. This means their internal skeletal structure is made of cartilage rather than bone, providing flexibility and reduced weight for life in the water. Phylum Chordata includes both jawless vertebrates (Agnatha) and jawed vertebrates (Gnathostomata). Reptilia have a four chambered heart with two auricles and two ventricles. Duck billed platypus and spiny anteater are oviparous mammals.

728. Which of the following features is not present in the Phylum Arthropoda?

• A. Parapodia
• B. Jointed appendages
• C. Chitinous exoskeleton
• D. Metameric segmentation

Explanation: Parapodia are flattened, fleshy, vertical flap like outgrowths of body wall found in annelids on lateral sides of trunk segments. These are hollow structures enclosing coelom which is continuous with that of trunk segments. These serve the dual purpose of locomotion and respiration.

729. Body having a meshwork of cells, internal cavities lined with food filtering flagellated cells and indirect development are the characteristics of which Phylum?

• A. Mollusca
• B. Protozoa
• C. Coelenterata
• D. Porifera

Explanation: Phylum Porifera (the sponges) has cellular level of body organisation, with inner cellular layer consisting of highly specialised flagellated cells called choanocytes (or collar cells). The development in this phylum is indirect as it includes a free swimming larva called amphiblastula or parenchymula for dispersal of the species.

730. A jawless fish lays eggs in fresh water and it has ammocoetes larvae after metamorphosis. This fish return to the ocean as _

• A. Neomyxine
• B. Petromyzon
• C. Eptatretus
• D. Myxine

Explanation: Petromyzon (Lamprey) belongs to the Class Cyclostomata of Phylum Chordata. It is a jawless fish which lays eggs in fresh water. The eggs hatch in about 3 weeks into minute transparent larvae called ammocoetes. After metamorphosis, the young lam preys swim down to the sea where they remain for 3 or 4 years before reaching maturity, when they once again migrate to streams or rivers to spawn and die. Gonads become mature when adults return to rivers for spawning.