Biology MCQs

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Radiations are not a biological agent that causes disease. Its physical agents cause disease along with electricity, pressure, heat, cold, etc.

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Alzheimer’s disease is a progressive neurologic disease of the brain leading to the irreversible loss of neurons and the loss of intellectual abilities, including memory and reasoning. These with time become severe enough to impede social or occupational functioning. Alzheimer’s disease is also known as simply Senile Dementia.

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Chameleons have specialized cells, chromatophores, which contain pigments in their cytoplasm, in three layers below their transparent outer skin. Dispersion of the pigment granules in the chromatophores sets the intensity of each color. Chromatophores contain pigments and reflect light, which are responsible for creating coloration. In chameleons, there are four types of chromatophores: xanthophores, erythrophores, iridiophores, and melanophores (Cooper and Greenberg, 1992).

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Monocost and dicots differ in the location of stomata and shape of guard cells. In monocots stomata are Dumb-bell shaped in dicots they are bean-shaped.

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Robert Hooke (1665) observed a section of cork under his microscope and found its structure resembling a ‘honey comb’. He gave the name ‘cell’ to each of the compartments of the honey comb like structure. Two German biologists, M Schleiden and T Schwann, later proposed the famous cell theory in 1938-39.

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The cerebrum or cortex is the largest part of the human brain, associated with higher brain function such as thought and action. Functions of the cerebrum include: initiation of movement, coordination of movement, temperature, touch, vision, hearing, judgment, reasoning, problem solving, emotions, and learning.

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DPT refers to a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis (whooping cough), and tetanus. The vaccine components include diphtheria and tetanus toxoids and killed whole cells of the organism that cause pertussis (wP).

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Smut of wheat is caused by Ustilago tritici. Rust is caused by Puccinia grlaminae. Mild symptoms may be present prior to heading, including yellowish leaf streaks and stiff, dark green leaves. Affected plants head out early, producing sterile heads with clumped, sooty olive-black spores in place of healthy glumes and kernels.

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Animal and vegetable fats serve as a concentrated energy source and are the highest energy sources in feedstuffs. Dietary fats and oils are a concentrated source of energy when compared to carbohydrate and protein, having over twice the amount of calories per gram.  Fats contain 2.25 times the calories per gram than protein or carbohydrates. Fats contain 9 calories/gm while protein and carbohydrates contain 4 calories per gram.

Notes:
The color of normal urine is usually light yellow to amber. Generally, the greater the solute volume the deeper the color. The yellow color of urine is due to the presence of a yellow pigment, urochrome. Deviations from normal color can be caused by certain drugs and various vegetables such as carrots, beets, and rhubarb.