Which of the following substances, if introduce in the blood stre

Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

A student wishes to study the cell structure under a light microscope having 10X eyepiece and 45X objective. He should illuminate the object by which one of the following colours of light so as to get the best possible resolution?

  • Yellow

  • Green

  • Blue

  • Red


2.

The net pressure gradient that causes the fluid to filter out of the glomeruli into the capsule is

  • 20 mm Hg

  • 75 mm Hg

  • 30 mm Hg

  • 50 mm Hg


3.

Centromere is required for

  • transcription

  • crossing over

  • cytoplasmic cleavage

  • movement of chromosomes towards poles


4.

Damage to thymus in a child may lead to

  • a reduction in haemoglobin content of blood

  • a reduction in stem cell production

  • loss of antibody mediated immunity

  • loss of cell mediated immunity


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5.

G-6-P dehydrogenase deficiency is associated with haemolysis of

  • lymphocytes

  • RBCs

  • platelets

  • leucocytes


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6.

Which of the following substances, if introduce in the blood stream, would cause coagulation, at the site of its introduction?

  • Fibrinogen

  • Prothrombin

  • Heparin

  • Thromboplastin


D.

Thromboplastin

Lipoproteinaceous, thromboplastin is released by the injured tissue. It reacts with Ca2+ ions present in blood and forms prothrombinase enzyme. Later, in the presence of Ca2+ ions, it inactivates heparin (anticoagulant) and catalyses prothrombin (inactive plasma protein) into an active thrombin protein. 

Thrombin acts as an enzyme and catalyses fibrinogen (soluble plasma protein) into an insoluble  fibre like polymer, fibrin. These form a dense network upon the wound and trap blood corpuscles and thus form a clot. This further seals the wound and stops bleeding

In blood vessels, thromboplastin does not release due to which blood does not clot. However, external thromboplastin causes blood clotting at the site of its introduction due to formation of prothrombinase enzyme.


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7.

Nucleotide are building blocks of nucleic acids, nucleotide is a composite molecule formed by

  • (base-sugar-phosphate)n

  • base-sugar-OH

  • base-sugar-phosphate

  • sugar-phosphate


8.

Which of the following is the simplest amino acid?

  • Tyrosine

  • Asparagine

  • Glycine

  • Alanine


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9.

Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these

  • enhance oxidative metabolism

  • are conjugated proteins

  • are exclusively synthesized in the body of a living organism as at present

  • help in regulating metabolism


10.

In a man, abducens nerve is injured. Which one ofthe following functions will be affected?

  • Movement of the eye ball

  • Swallowing

  • Movement of the tongue

  • Movement of the neck


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