Free Biodiversity and Variety of Life MCQs with Answers

2691. Linnaeus was credited with:

• A. Binomial nomenclature
• B. Theory of biogenesis
• C. Discovery of microscope
• D. Evolution through natural selection

Explanation: Binomial nomenclature of scientific naming was first given by C. Linnaeus (1735) in his book Systema Naturae and later in "Species Plantarum" (1753). He used two Latin words for any organism, the first being a generic name and the second being a specific name. The generic name begins with a capital letter, and the species name with a small letter.

2692. The basic unit, or smallest taxon, of taxonomy/classification is

• A. Species
• B. Kingdom
• C. Family
• D. Order

Explanation: The basic unit or smallest taxon of taxonomy/classification is species. Species are groups of organisms that have numerous physical features in common and are capable of interbreeding and producing fertile offspring. Taxonomists use species as the starting point for organizing and categorizing living organisms into broader hierarchical groups. The hierarchy of biological classification, from most specific to most general.

2693. Viruses that infect bacteria are called:

• A. Prophage
• B. Provirus
• C. Bacteriophage
• D. Virions

Explanation: A provirus and a virion are not the entities that specifically affect bacteria because they refer to general stages or forms of viruses rather than specialized viruses that target bacterial cells. A provirus is the stage of a viral genome when it integrates into the DNA of a host cell, usually seen in retroviruses infecting eukaryotic cells such as humans (e.g., HIV). A virion, on the other hand, is the complete, fully assembled, and infectious form of a virus particle, which can infect a host but is not restricted to bacteria-it may target plants, animals, or humans depending on the virus type. The viruses that specifically infect and destroy bacteria are called bacteriophages (or simply phages). These bacteriophages attach to bacterial cells, inject their genetic material, and use the bacterial machinery to replicate, ultimately causing the lysis (destruction) of the bacteria. For example, the T4 bacteriophage is a well-studied virus that infects and destroys Escherichia coli bacteria.

2694. Reverse transcriptase can convert:

• A. DNA to RNA
• B. RNA to DNA
• C. DNA to proteins
• D. RNA to proteins

Explanation: Reverse transcriptase is a key enzyme in certain viruses, such as retroviruses, which include HIV. It allows these viruses to replicate their RNA genome into DNA and integrate it into the host cell's genome. This conversion is crucial for the virus's life cycle and is an essential step in retroviral replication.

2695. Choose the correct statement.

• A. All mammals are viviparous
• B. All cyclostomes do not possess jaws and paired fins
• C. All reptiles have a three chambered heart
• D. All pisces have gills covered by an operculum

Explanation: All cyclostomes lack true jaws and paired fins. Cyclostomes are jawless fish characterized by their round, sucker-like mouths for feeding and a single median fin for propulsion. Ornithorhynchus and Tachyglossus are oviparous mammals. Crocodile is a reptile which possesses four chambered heart. In cartilaginous fish (except Chimaera) gills are not covered by an operculum.

2696. All of the following coelenterates show alternation of generation except:

• A. Hydra
• B. Obelia
• C. Aurelia
• D. All of these

Explanation: Metagenesis or alternation between polyp and medusa forms is a characteristic feature of phylum cnidaria. However, hydra exists only as a polyp and does not exhibit metagenesis.

2697. Free living example of Platyhelminthes is?

• A. Dugesia
• B. Fasciola
• C. Taenia
• D. All of these

Explanation: Option Ais correct.Yes, Dugesia is a free-living example of Platyhelminthes. Platyhelminthes are a phylum of animals that includes flatworms. Flatworms are invertebrates, which means they do not have a backbone. They are also triploblastic, which means they have three germ layers in their embryos. There are two main classes of Platyhelminthes: Turbellarians and Trematodes. Dugesia is a type of Turbellarian, which are free-living flatworms. Dugesia are found in freshwater habitats, such as ponds and streams. They are typically small, measuring only a few centimeters in length. They have a flattened body with a smooth, slippery surface. Dugesia are carnivores, and they eat small invertebrates, such as insects and worms. They have a simple digestive system that consists of a mouth, a pharynx, and an intestine.

2698. Which of the following are motile zooids in cnidarians?

• A. polyps
• B. Medusae
• C. Both A and B
• D. None of these

Explanation: Polyps are sessile, or attached, zooids in cnidarians. They are typically cup-shaped and have tentacles that they use to capture prey. Medusae are free-swimming zooids in cnidarians. They are typically bell-shaped and have tentacles that they use to capture prey.

2699. Which of following system is segmentally arranged in annelids?

• A. Excretory system
• B. Digestive system
• C. Circulatory system
• D. Nervous system

Explanation: The circulatory system in annelids is segmentally arranged with segmental vessels distributing blood along the body segments.

2700. Which statement correctly describes the alimentary canal of Hydra?

• A. The alimentary canal is formed from the endodermal cells
• B. The alimentary canal has a single opening
• C. The alimentary canal is sac-like
• D. All of these

Explanation: All three statements correctly describe the alimentary canal of Hydra.