Biology MCQs

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Infection is the invasion of an organism’s body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious diseases can be spread from one person to another, for example through contact with bodily fluids, by aerosols (through coughing and sneezing), or via a vector, for example a mosquito.

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The pigment that gives human skin, hair, and eyes their color. Dark-skinned people have more melanin in their skin than light-skinned people have. Melanin is produced by cells called melanocytes. Everyone has the same number of melanocytes, but some people make more melanin than others.

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Mycobacterium leprae is a bacillus (rod-shaped) bacterium that causes leprosy, also known as “Hansen’s disease”, which is a chronic infectious disease that damages the peripheral nerves and targets the skin, eyes, and muscles, upper respiratory tract, and nasal mucosa (lining of the nose).

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Changes in pH which can accompany metabolic process such as respiration (aerobic glycolysis for example) can alter the conformation of an enzyme and hence enzyme activity such as salivarya mylase is effective in neutral condition, pepsin in acidic condition l.5 (less than pH 7) and trypsin in basic condition (more than pH 7).

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Silk worms are the larva of a moth (Bombyx mori) native to Asia that spins a cocoon of fine, strong, lustrous fiber that is the source of commercial silk. Silkworms feed on the leaves of the mulberries (genus- Morus) and sometimes on the Osage orange (Maclura pomifera).

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Microcytic anaemia: anemia characterized by small red blood cells, due to deficiency of iron; Pernicious anaemia: body does not make enough red blood cells due to lack of vitamin B12; Goitre: swelling of the neck or larynx resulting from iodine deficiency; and Pellagra: chronic lack of niacin (vitamin B3). It is also called 3-D disease.

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Pneumatic bone is hollow bone filled with air, connected to the respiratory system. Many of a bird’s bones are pneumatic as an adaptation to flying. For flight to occur in Aves, four physical forces (thrust and drag, lift and weight) must work together. In order for birds to balance these forces, certain physical characteristics are required. Which most of the flying birds have acquired in one way or other.

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Water-soluble vitamins are those that dissolve in water upon entering the body. Because of this, body cannot store excess amounts of water-soluble vitamins for later use. There are a total of nine water-soluble vitamins: the B vitamins- folate, thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B6 and vitamin B12 and vitamin C.

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Hepatitis is an inflammation of the liver. Viruses cause most cases of hepatitis. There are 5 main hepatitis viruses, referred to as types A, B, C, D and E. The type of hepatitis is named for the virus that causes it; for example, hepatitis A, hepatitis B or hepatitis C. Drug or alcohol use can also cause hepatitis.

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Tropism is a growth movement whose direction is determined by the direction from which the stimulus strikes the plant. Most stems are positively phototropic, while most roots are said to be negatively phototropic and positively geotropic.