The scientific reasons of biology.

1. Chapter 3
Co-ordination and control
(Exams are not the obstacles of our course
they are like myelin sheath for the rapid
conduction of impulses, the rapid progress)
Biological Reasons: 1 Dr. Sajid Ali Talpur

2. Q 1: Do plants feel pain?
Ans. No, because they do not have nervous system.
Q 2: Which phytohormone is known as growth
promoter and why?
Ans. Most of the hormones act as growth promoter
but Gibberelin serves for the purposes by winding
up dwarfism.
Q 3: Why certain plants get delayed age and live
long?
Ans. It happens so because of the high quantity of
cytokinins and low quantity of abscisic acid.. since
cytokinin promotes the production of chlorophyll.
Q 4: Why the emerge of abscission layer causes fall
of the fruit?
Ans. Because it serves as the separating agent
between the fruit and stalk, also it breaks or
weakens the other connecting cells.
Q5: Why certain plants undergo parthenocarpy?
Ans. Certain plants undergo production of fruits
without fertilization, known as parthenocarpy which
is caused by several factors but mostly due to high
concentration of auxins.
Q6: How ethen works as fruit ripening agent?
Ans: It affects permeability of cell membrane which
activates the enzymes to destroy chloroplast
subsequently red and yellow colors appear and the
fruit assumes the ripened color.
Biological Reasons: 2 Dr. Sajid Ali Talpur

3. Q 7: How plants response to herbivory?
Ans. they overcome herbivory by developing thorns
and producing distasteful or toxic compounds.
Q 8: How plants response to heat stress?
Ans. They overcome over heating by transpiration
as a cooling effect and by producing heat shock
proteins when temperature is above 40oC, which
prevent enzymes and other metabolic proteins from
getting denatured.
Q 9: What is the role of hormones in drought
conditions?
Ans. Abscisic acid is release from mesophyll cells
in leaf, which keeps stomata close and supports
water conservation by reducing transpiration.
Q10. Why biorhythms are called endogenous?
Ans. Because they do not depend upon external
factors like light and temperature but on internal
system.
Q11: Which of the three types of neurons is slow
impulse conducting and why?
Ans. Inter neuron because it is unmylinated. Since it
is in CNS and covers a small distance so the slow
conduction is sufficient.
Q12. How do you differentiate between sensation
and perception?
Ans. The awareness of stimulus is called sensation
and the recognition of the stimulus is called
perception.
Biological Reasons: 3 Dr. Sajid Ali Talpur

4. Q13: What is the effect on nervous system of not
taking salt at all?
Ans. there will be nerve impulse and conduction
problems. Because Na (mainly obtained from salt)
along with potassium maintains RMP, also the entry
of Na ions into the neuron is the primary
requirement of action potential.
Q14: Why synapse requires neurotransmitters for
the transmission of impulse?
Ans. because there is a gap between the two
neurons and the impulse can not be transmitted
directly. Therefore neurotransmitters carry signals
from one presynaptic membrane through synaptic
cleft to the postsynaptic membrane and cause
depolarization in it. In this way the nerve impulse is
transmitted from one neuron to another neuron with
the help of neurotransmitters.
Q15: What is the significance of reflex action?
Ans. Reflex Actions are automatic, involuntary
responses due to either internal or external stimuli,
which protect us from deep damages like hand
withdrawal on a painful stimulus, blinking of eyes
protecting entry of insects etc.
Q16: Can a chick consider duck his mother instead
of hen?
Ans. Yes, provided, the chick finds duck as its
mother when it hatches and it will follow the duck
as its mother no matter its real mother i.e. hen is
present. This is called imprinting.
Biological Reasons: 4 Dr. Sajid Ali Talpur

5. Q17: What do you think learned behavior is more
common in humans or other animals?
Ans. In humans. Because they are born totally
ignorant while the animals are highly educated
about their requirements by birth.
Q18: Lion is not as aggressive in zoo as in jungle.
How do you explain this statement?
Ans. This is a learned behavior called habituation in
which the lion has adapted to remain calm in the
zoo.
Biological Reasons: 5 Dr. Sajid Ali Talpur