- (c)
- (b) Irregular bumps or conules are found in
demospongiae like Euspongia.
- (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.
- (a) Frogs are Ureotelic, spinal cord passes through
foramen of munro.
- (a)
- (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.
- (c) Majority of mammals have seven cervical
vertebrae including camels,whale and humans.
- (c) Tryptophan is a precursor to neurotransmitters
Serotonin and Melatonin.
- (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.
- (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.
- (b)Posterior pituitary secretes vasopressin which
stimulates resorption of water in the distal tubules
in the nephron.
- (a) 21. (c)
- (c)
- (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.
- (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.
- (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.
- (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.
- (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.
- (b)
- (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.
- (a) Blood pressure gradually decreases from
the aorta to the large arteries, to arterioles, to
capillaries, then finally is the lowest in the veins.
- (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.
