BIOLOGY TIMES — January 2018

(ff) #1

  1. (c)

  2. (b) Irregular bumps or conules are found in
    demospongiae like Euspongia.

  3. (b) Depending upon the observations Darwin
    made during his voyage, he came to a conclusion
    that the existing living organisms share
    similarities not only with the other organisms
    but also with the other organisms which existed
    millions of years ago.

  4. (a) Frogs are Ureotelic, spinal cord passes through
    foramen of munro.

  5. (a)

  6. (b) Kinetin is a type of cytokinin, a class of plant
    hormone that promotes cell division. Kinetin was
    originally isolated by Miller and Skoog et al. It
    has ability to induce cell division, provided auxin
    was present in the medium and often used in plant
    tissue culture for inducing formation of callus
    in conjunction with auxin and regenerate shoot
    tissues from callus in lower concentration of
    auxin, higher concentration of auxin regenerates
    roots.

  7. (c) Majority of mammals have seven cervical
    vertebrae including camels,whale and humans.

  8. (c) Tryptophan is a precursor to neurotransmitters
    Serotonin and Melatonin.

  9. (b) There will be great reduction in the size
    of a population because of a natural calamity,
    this will greatly reduce genetic variability of
    that population. In the remaining population
    some genes are over presented, some are under
    represented and some are eliminated.

  10. (a) When a person views a far-away object, the
    ciliary muscle relaxes and the lens flattens. This
    helps in relieving eye strain by gazing into the
    distance. Both Assertion and Reason are true and
    Reason is the correct explanation of Assertion.

  11. (b)Posterior pituitary secretes vasopressin which
    stimulates resorption of water in the distal tubules
    in the nephron.

  12. (a) 21. (c)

  13. (c)

  14. (d) Discontinuing the progesterone will cause the
    period to start. Progesterone plays a crucial role in
    reproduction. First, it prepares the uterus for the
    implantation of a fertilised egg. Without adequate
    progesterone in the uterine wall, the egg cannot
    attach itself and is expelled.

  15. (d) Red muscle fibres are dark red in colour due
    to presence of Myoglobin a red haemoprotein.


Myoglobin binds and stores oxygen as
oxyhaemoglobin. Oxyhaemoglobin will release
oxygen for utilisation during muscle contraction.
Red muscle fibre is rich in mitochondria and it
carries out aerobic oxidation. Red muscle fibre
carries out sustained work at slow rate for a long
time.


  1. (d) Pollen grains of many species can germinate
    can not germinate on the stigma of a flower, but
    only one pollen tube of the same species grows
    into the style.

  2. (d)The epiglottis is a flap that is made of elastic
    cartilage tissue covered with a mucous membrane
    attached to the entrance of the larnynx. It prevents
    the entry of food into the larnyx and directs it to
    the Oesophagus. Due to the improper movement
    of epiglottis, one may suddenly start coughing
    while swallowing some food.

  3. (c) Walls of glomerular capillaries and Bowman’s
    capsule are very thin and are semi-permeable due
    to the presence of pores in the former and slit-
    pores in the latter. They allow water and small
    molecules in the blood to pass through them.
    Fluid containing these materials is forced out
    of the glomerular capillaries into the Bowman’s
    capsule by the high pressure of the blood in the
    glomerular capillaries.
    This pressure is about 70 mm Hg in man. The
    fluid tends to move in the reverse direction due
    to (i) the osmotic pressure of plasma proteins
    in the glomerular capillaries and (ii) hydrostatic
    pressure of the fluid in the urinary tubule. These
    pressures in man are about 30 mm. Hg. and 20
    mm. Hg. respectively. The net force moving the
    fluid from the glomerular capillaries, called the
    filtration pressure, is 70 – (30 + 20) or 20 mm. Hg.

  4. (b)

  5. (c) Plasma cells, also called plasma B cells,
    plasmocytes, plasmacytes, or effector B
    cells, are white blood cells that secrete large
    volumes of antibodies. They are transported
    by the blood plasma and the lymphatic system.

  6. (a) Blood pressure gradually decreases from
    the aorta to the large arteries, to arterioles, to
    capillaries, then finally is the lowest in the veins.

  7. (c) Haemophilia is an inherited genetic disorder
    that impairs the body’s ability to make blood clots,
    a process needed to stop bleeding. Hemophilia A
    is the most common type of hemophilia, and it’s
    caused by a deficiency in factor VIII. Thus, the
    above Assertion is true but Reason is false.

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