Biology GK Questions Quiz-33

Biology GK Questions Quiz-33

Biology Multiple Choice Questions (MCQs) Quiz for State and UPSC Civil Services Examinations. Objective Questions on Biology for competitive examinations.

    641. Quinine, the commonly used drug to treat malaria, is obtained from a plant. What part of the plant yields the drug ?

    (1) Leaves 
    (2) Fruits
    (3) Root 
    (4) Stem bark
    Answer:
    641. (4) Quinine, as a component of the bark of the cinchona tree, was used to treat malaria from as early as the 1600s. The bark of trees in this genus is the source of a variety of alkaloids, the most familiar of which is quinine, an antipyretic (anti-fever) agent.

    642. Most fish do not sink in water because of the presence of

    (1) air sinuses
    (2) buoyant scales on the body
    (3) swim bladder
    (4) swimmerets
    Answer:
    642. (3) Most fish are able to control their bouyancy with a swim bladder (an internal sac they can fill with gas or water) or by other means, so that they have a specific gravity exactly the same as the water they swim in. By small adjustments to their buoyancy, they can float to a higher level or sink lower with a very small expenditure of energy.

    643. Heavy alcohol consuming people generally die of

    (1) blood cancer
    (2) cirrhosis
    (3) liver or stomach cancer
    (4) weakening of heart muscles leading to cardiac arrest
    Answer:
    643. (2) Cirrhosis is scarring of the liver and poor liver function. It is the final phase of chronic liver disease which may result from a history of excess drinking habits. Cirrhosis is most commonly caused by alcoholism, hepatitis B and hepatitis C, and fatty liver disease.

    644. Chocolates can be bad for health because of a high content of

    (1) cobalt 
    (2) nickel
    (3) zinc 
    (4) lead
    Answer:
    644. (4) Chocolate absorbs lead from the environment during production. Recently there has been concern of mild lead poisoning for some types of chocolate.

    645. Which carbohydrate is used in silvering of mirrors ?

    (1) Fructose 
    (2) Sucrose
    (3) Glucose 
    (4) Starch
    Answer:
    645. (3) Glucose is used in silvering of mirror as a reducing agent. Aldehydes such as glucose reduce Ag+ (aq) ions to metallic silver. They themselves are oxidised to carboxylate ions.

    646. When a child is born, what happens to its blood circulation ?

    (1) Its blood flows for the first time
    (2) Its blood reverses its flow through the heart
    (3) Its blood ceases to pass from one atrium to the other
    (4) Its blood carries wastes for the first time
    Answer:
    646. (4) The Fetal circulatory system is unique during pregnancy before the lungs first come into use at
    birth. Its circulatory system must reorient itself to send all the blood through the lungs to receive oxygen. The baby is cut off from the placenta, which was previously its only source of nourishment. The blood vessels that ran through the umbilical cord constrict and close. All this happens in a few moments when the baby is born.

    647. Which virus from the following combinations is contagious for human beings

    (1) H5N1 
    (2) H2N3
    (3) H4N1 
    (4) H4N2
    Answer:
    647. (1) A bird-adapted strain of H5N1, called HPAI A(H5N1) for "highly pathogenic avian influenza virus of type A of subtype H5N1", is the causative agent of H5N1 flu, commonly known as "avian influenza" or "bird flu”.

    648. Cuscuta is a

    (1) partial stem parasite
    (2) complete stem parasite
    (3) partial root parasite
    (4) complete root parasite
    Answer:
    648. (2) Cuscuta (Dodder) is a genus of about 100-170 species of yellow, orange or red (rarely green) parasitic plants. Dodders are supremely adapted for a life of plunder and pillage. Reduced in form to scrambling and twining threads, they appear to be completely leafless, although closer inspection reveals tiny scale leaves pressed close to the stems. So it is a stem parasite.

    649. Plants differ from animals in having

    (1) locomotion
    (2) metabolism
    (3) localised growth
    (4) catabolism
    Answer:
    649. (3) Plants produce new cells and grow only in their shoot and root apical meristems and leaf primordia; this is localized growth. In contrast, all parts of an animal's body grow (diffuse growth). From the time we are embroys until we are about 18 years old, all parts of our body grow simultaneously. Due to a plant's localized growth, an individual plant can have older, completely mature and highly functional leaves at the same time that it is still producing new leaves.

    650. The function of the heart is to

    (1) Supply oxygen to the tissues
    (2) carry carbon dioxide from the tissues
    (3) throw away waste materials
    (4) pump blood to different parts of the body
    Answer:
    650. (4) The heart is a hollow muscle that pumps blood throughout the blood vessels by repeated, rhythmic contractions. In mammals, the function of the right side of the heart (see right heart) is to collect deoxygenated blood, in the right atrium, from the body (via superior and inferior vena cavae) and pump it, through the tricuspid valve, via the right ventricle, into the lungs (pulmonary circulation) so that carbon dioxide can be dropped off and oxygen picked up (gas exchange). This happens through the passive process of diffusion.

    651. The red colour of human blood is due to

    (1) myoglobin
    (2) hemoglobin
    (3) immunoglobulin
    (4) haptoglobin
    Answer:
    651. (2) Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates which carries oxygen from the respiratory organs to the rest of the body. It changes shape when it binds oxygen. When it changes shape, it absorbs different wavelengths of light, making it change color. When blood is exposed to air, much more of the hemoglobin absorbs oxygen than had in the vein the blood came from. Therefore, the blood turns red.

    652. The functional unit of the kidney is

    (1) neuron
    (2) glomerulus
    (3) nephron 
    (4) ureter
    Answer:
    652. (3) Nephron is the basic structural and functional unit of the kidney. Its chief function is to regulate
    the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing
    what is needed and excreting the rest as urine. A nephron eliminates wastes from the body, regulates
    blood volume and blood pressure, controls levels of electrolytes and metabolites, and regulates blood pH.

    653. Which of the following is called the powerhouse’ of the cell ?

    (1) Nucleus
    (2) Lysosome
    (3) Chromosome
    (4) Mitochondrion
    Answer:
    653. (4) Mitochondria are sometimes described as "cellular power plants" because they generate most of the cell's supply of adenosine tri-phosphate (ATP), used as a source of chemical energy. In addition to supplying cellular energy, mitochondria are involved in other tasks such as signaling, cellular differentiation, cell death, as well as the control of the cell cycle and cell growth.

    654. Acquired Immuno-Deficiency Syndrome (AIDS) is caused by

    (1) protozoa 
    (2) virus
    (3) fungus 
    (4) bacteria
    Answer:
    654. (2) Human immunodeficiency virus infection / acquired immunodeficiency syndrome (HIV/AIDS) is a disease of the human immune system caused by the human immunodeficiency virus (HIV).

    655. Which of the following processes does not increase the amount of carbon dioxide in air ?

    (1) Breathing
    (2) Photosynthesis
    (3) Burning of petrol
    (4) Aerobic decay of vegetation
    Answer:
    655. (2) Plants reduce the CO2, because they use it with photosynthesis. They use it to give oxygen and
    carbohydrates as the final product. It is for this reason that plantation of trees has been stressed by
    environmentalists.

    656. The vitamin that is most readily manufactured in our bodies is

    (1) vitamin A 
    (2) vitamin B
    (3) vitamin C 
    (4) vitamin D
    Answer:
    656. (4) Vitamin D is not really a vitamin, but a precursor for the most potent steroid hormone in the human body. It can be obtained from exposure to the sun’s ultraviolet (UV) radiation, especially during the early morning hours.

    657. Which cells in our body have the least regenerative power?

    (1) Brain cells 
    (2) Muscle cells
    (3) Bone cells 
    (4) Liver cells
    Answer:
    657. (1) Brain cells do not regenerate. Once lost, they do not come back. Research from Karolinska Institute in Sweden haves shown that the nerve cells of the brain remain the same throughout a person's life.

    658. A potato tuber has been cut into two halves. A few drops of iodine solution are placed on the cut surface of one of the halves. What colour change will be noticed?

    (1) From brown to blue–black
    (2) From brown to orange–red
    (3) From blue to pink
    (4) From pink to blue–green
    Answer:
    658. (1) Any form of starch (carbohydrate) turns blue-black when iodine solution is applied to it. This is because starch is composed of polymers of glucose. Long linear chains are amylose. Amylopectin is similar but contains a branch point about every 25th glucose or so. Amylose coils into a helical secondary structure resembling a tube with a hollow core. Certain molecules including fatty acids and iodine can lodge inside the core as already mentioned. The complex of iodine stuck inside the amylose coil produces a characteristic blue-black colour.

    659. How many valves does a human heart have?

    (1) Four 
    (2) Three
    (3) Two 
    (4) One
    Answer:
    659. (1) Human heart has four valves: two atrioventricular (AV) valves, which are between the atria and the ventricles, are the mitral valve and the tricuspid valve; and two semilunar (SL) valves, which are in the arteries leaving the heart, are the aortic valve and the pulmonary valve. A heart valve normally allows blood flow in only one direction through the heart.

    660. The cells which are responsible for the production of antibodies are

    (1) red blood cells
    (2) neutrophils
    (3) lymphocytes
    (4) platelets
    Answer:
    660. (3) An antibody (Ab), also known as an immunoglobulin (Ig), is a large Y-shaped protein produced by B-cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. Each antibody is produced by lymphocytes (specialized white cells) as a result of exposure to specific chemical substances called antigens usually on the outside of an invading organism. This is called the antigen-antibody reaction.

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