Competitive Exams: Zoology MCQs (Practice-Test 15 of 112)

    • Assertion (A): Myoglobin bears an ironcontaining heme group capable of combining reversibly with oxygen.
    • Reason (R): Myoglobin is made up of a monomeric polypeptide chain without a tertiary structure.
    1. Both A and R are individually true and R is the correct explanation of A

    2. Both A and R are individually true but R is not the correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): On the yearly basis, the net community production in a mature rain forest tends to be very low or none.
    • Reason (R): In steady-state communities the gross primary production tends to be totally dissipated by the combined autotrophic and heterotrophic respirations.
    1. Both A and R are individually true and R is the correct explanation of A

    2. Both A and R are individually true but R is not the correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Ethylene oxide has been used as an insecticide.
    • Reason (R): Ethylene oxide is an anticholinesterase.
    1. Both A and R are individually true and R is the correct explanation of A

    2. Both A and R are individually true but R is not the correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

    • Assertion (A): Mental and motor retardation and death by ages 2 − 4 years are phenotypic effects in the individuals of Tay-Sachs disease.
    • Reason (R): In the individuals of Tay-Sachs disease galactose-I-phosphate uridyl transferase fails to catalyze transformation of galactose into glucose.
    1. Both A and R are individually true and R is the correct explanation of A

    2. Both A and R are individually true but R is not the correct explanation of A

    3. A is true but R is false

    4. A is false but R is true

  1. Acid phosphatase is a ‘market’ enzyme for

    1. ribosome

    2. nucleus

    3. mitochondrion

    4. lysosome

  2. Which of the following is retained by marine elasmobranches in their body fluids and tissues for osmoregulatory purposes?

    1. water

    2. allantoin

    3. uric acid

    4. urea

  3. An enzyme molecule can be inactivated by changing its shape by

    1. Coenzyme

    2. Hormone

    3. Allosteria inhibitor

    4. Competitive inhibitor

  4. Aldosterone, a mineralocorticoid produced by the adrenal cortex acts on the renal tubules to promote

    1. retention of Na + and excretion of K +

    2. retention of Na +, K + and H +

    3. retention of K + and H + and excretion of Na +

    4. excretion of Ca + + and retention of

    Mg + +

  5. In the respiratory chain, the only soluble Cytochrome is

    1. cytochrome a

    2. cytochrome b

    3. cytochrome c

    4. cytochrome a3

  6. Consider the following processes:

    1. Breakdown of creatin phosphate

    2. Conversion of ATP into ADP

    3. Formation of lactic acid

    4. Formation of fructose diphosphate

    The correct sequence of these events during muscular contraction is

    1. 4, 3, 2, 1

    2. 2, 1, 4, 3

    3. 4, 1, 2, 3

    4. 2, 3, 4, 1

  7. The renal threshold for glucose excretion corresponds generally to a plasma glucose level of

    1. 100 mg/dl

    2. 120 mg/dl

    3. 60 mg/dl

    4. 180 mg/dl

  8. Which of the following is NOT an intracellular buffer?

    1. Haemoglobin

    2. HCO3-

    3. Carbonate

    4. Protein

  9. Consider the following statements Constriction of the renal artery would result in an increase in mean arterial pressure due to

    1. increased rennin secretion

    2. increased angiotensin II formation

    3. decreased plasma bradykinin levels

    4. increased aldosterone secretion

    Which of these statements are correct?

    1. 1, 2 and 3

    2. 2, 3 and 4

    3. 1 and 4

    4. 1, 2, 3 and 4

  10. Excess of nerotransmitter causes

    1. increase in the number of active receptors

    2. decrease in the number of active receptors

    3. inactivation of all receptors

    4. modification of receptors

  11. Oxytocin does NOT cause

    1. myoepithelial cell contraction

    2. myometrial contraction

    3. milk ejection

    4. lactogenesis