General Science Questions (MCQs) for Competitive Examinations

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Males carry two different types of chromosomes (XY) while the females carry two chromosomes of single type X and (XX). An XY combination produces a boy baby and an XX combination produces a girl baby. Thus, males are responsible for the determination of the sex of the child.

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A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids. It refers to the use of wood tannins from oak in tanning animal hides into leather.

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The foramen magnum (“great hole”) is a large opening in the occipital bone of the cranium. It is one of the circular apertures in the base of the skull (the foramina), through which the spinal cord (an extension of the medulla oblongata) enters and exits the skull vault.

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Phototropism is the growth of organisms in response to light. In plants, phototropism is a response to blue wavelengths of light and is caused by a redistribution of auxin from the illuminated side to the darker side of the shoot, resulting in quicker growth on the darker side and bending of the shoot toward the source of light.

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Pneumonia is a bacterial disease caused by Streptococcus pneumoniae, a Gram-positive bacterium. It lives in the noses and throats of healthy people and can enter lungs through inhalation. Other important Gram-positive causes of pneumonia are Staphylococcus aureus and Bacillus anthracis.

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The activity of enzymes, which are generally globular proteins, is determined by their three-dimensional structure. This structure allows them to bind to a substrate and catalyze their involvement in a reaction. Enzymes vary in size, ranging from 62 amino acid residues for the monomer of 4-oxalocrotonate tautomerase, to over 2,500 residues in animal fatty acid synthase. Their specific ability to bind to substrates enables reactions to occur in the body, playing a crucial role in metabolism.

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A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Veins are components of the cardiovascular system, which circulates blood to provide nutrients to the cells of the body. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins.

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There are three types of heterotrophs: herbivores, carnivores and omnivores. Also referred to as consumers, heterotrophs are organisms that obtain their energy from organic compounds. In other words, they are organisms that are unable to produce their own food (unlike autotrophs) and therefore have to consume/ ingest organic compounds as a source of energy.

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In algae, sexual reproduction takes place through fusion of two gametes. It is of two types on the basis of the size of gametes : isogamous (where male and female gametes are morphologically similar) and heterogamous (anisogamous and oogamous). Anisogamous fusion happens when gametes are dissimilar in size.

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Prothallus is usually the gametophytic stage in the life of a fern or other pteridophyte. The prothallium develops from a germinating spore. It is a shortlived and inconspicuous heart-shaped structure.