scientific reasons in inter biology.

1. Chapter 2
Support and Locomotion
(Failure is like joints in the body which is the
primary tool to walk but if you do not walk
you will not progress and become immobile)
Biological Reasons: Dr. Sajid Ali Talpur

2. Q1: Why does wilting take place during hot
summer?
Ans. Because of the high temperature in the
summer transpiration is increased causing
deficiency of water and subsequently over heating.
In order to avoid over heating in the plant body and
to save the water wilting is brought about.
Q2: Why sclerenchyma cells become dead on
maturity?
Ans. Because they have to provide support and act
as outer covering so their walls are already
thickened and on reaching maturity nearly all the
lumen vanishes only the dead material persists in
the cells.
Q3: Why does wilting happen with the loss of
turgidity in the herbaceous stem?
Ans. Since the herbaceous stem depends only on the
turgidity to stand erect if it is lost, the stem loses its
erection strength and falls off.
Q4: How does earth worm move:
Ans. Because of the hydrostatic skeleton and the
presence of two types of muscles i.e.circular and
elongated. When circular muscles contract and
elongated muscles contract the body elongates and
shortens respectively
Q5: How does the exposed tissue of cortex become
protected when primary epidermis falls off?
Ans. To protect the exposed tissue and to increase
in diameter, a layer of meristematic cells, the cork
Biological Reasons: Dr. Sajid Ali Talpur

3. cambium or phellogen arises in the cortex. The cells
of phellogen actively divide and give off new cells
on both sides towards cortex are parenchymatous
and form secondary cortex or phelloderm while the
cells on the outer side of phelloderm are
reactangular and arranged in radial rows. They
deposit a waxy material called suberin in their wall
and then die. These cork tissues function as a barrier
and protect stem from physical damage and
pathogens. Due to its waxy nature it prevents water
loss from the srem.
Q6: How bones help in homeostasis?
Ans. Basically bones marvelous structure and
composition is responsible for homeostasis. It is in
such a way that the bones allow excess blood Ca to
be deposited in them as a result of calcitonin
secretion and to maintain blood ionic concentration,
demineralization occurs under the control of PTH.
Q7: Do molluscs undergo moulting? If not then
why?
Ans. their highly modified structure allows them to
grow constantly and persist exoskeleton to form
rings instead of moulting (ecdysis)
Q8: Does exoskeleton contain sensory receptors:
Ans. Yes, it contains sensory receptors known as
sensila which are present in the form of bristles and
lenses
Biological Reasons: Dr. Sajid Ali Talpur

4. Q9: How do various skeletons help in movement?
Ans. In case of exoskeleton it provides attachment
for muscles whereas the joints in endoskeleton and
pressure of the hydrostatic skeleton cause the
animal to move swiftly.
Q10: How does exoskeleton provide support and
protection?
Ans. its outer layer the epicuticle is made up of
waxy lipoproteineous material which is
impermeable to water, serving as a barrier for
microbes and protects the animal from being easy
prey?
Q11: Why bones not slip and dislocate even at
moveable joints?
Ans. because at moveable joints, the bones are held
in place by strong straps of connective tissue called
ligaments.
Q12. Why suture joints are needed?
Ans. However, they are immoveable yet required to
provide compensated shape to the brain.
Q13: Why skeleton muscles get readily fatigue?
Ans. Because they are voluntary in action also the
accumulation of lactic acid due fermentation causes
the muscles to fatigue.
Q14: How cardiac muscles are unique to skeleton
and smooth muscles?
Ans. They are unique because they contain the
properties of both the skeletal and smooth muscles
Biological Reasons: Dr. Sajid Ali Talpur

5. as striated and involuntary in action respectively.
Also they initiate working before birth and stop at
death.
Q15: Where does a muscle receive energy from to
contract?
Ans. The energy obviously comes from the food but
through some intermediates like glycogen and
creatine which release ATP for muscle contraction.
Q16. How can we estimate the age of a plant?
Ans. the age of a plant can be estimated by counting
the annual rings which are actually the secondary
xylem in the form of concentric layers, consists of
inner zone of spring wood and outer zone of
summer wood.
Q17: Can water cause locomotion?
Ans. Yes! It causes locomotion in the form of jet
propulsion as seen in jelly fish. Also the most of the
hydrostatic skeleton is water.
(Reference: Text books of biology for class 12)
Biological Reasons: Dr. Sajid Ali Talpur

6. as striated and involuntary in action respectively.
Also they initiate working before birth and stop at
death.
Q15: Where does a muscle receive energy from to
contract?
Ans. The energy obviously comes from the food but
through some intermediates like glycogen and
creatine which release ATP for muscle contraction.
Q16. How can we estimate the age of a plant?
Ans. the age of a plant can be estimated by counting
the annual rings which are actually the secondary
xylem in the form of concentric layers, consists of
inner zone of spring wood and outer zone of
summer wood.
Q17: Can water cause locomotion?
Ans. Yes! It causes locomotion in the form of jet
propulsion as seen in jelly fish. Also the most of the
hydrostatic skeleton is water.
(Reference: Text books of biology for class 12)
Biological Reasons: Dr. Sajid Ali Talpur