CBSE Biology Class-Xll Questions

11/28/2011 CBSE

Q1. At what stage the embryo is
implanted in the uterus of the mother in case of a test tube baby? 

Ans1.
32-celled Morula.


Q2. Human heart is Myogenic yet a
parasympathetic nerve can reduce the heart rate. Name the nerve.

Ans2.
Vagus Nerve.


Q3. Which of the following
diseases could be avoided by analysing the pedegree of parents – Klinefelter’s
syndrome, Haemophilia, Amoebiasis.

Ans3.
Haemophilia.


Q4. Name the functional
contractile unit of the muscle.

Ans4.
Sarcomere.


Q5. Name any two synthetic auxins
used in agriculture.

Ans5.
(i) NAA (naphthaleneacetic acid)


(ii) 2,4 D
(2,4-dichlorophenoxyacetic acid)


Q6. What is pulvinus?

Ans6.
Pulvinus is the swollen base of the leaf in many members of the bean
family. It is responsible for sleep movements.


Q7. Name the fluid in which
membranous labyrinth of the inner ear floats.

Ans7.
Perilymph.


Q8. In a round worm the volume of
the body increases due to the growth of the body cells without increase in their
number. What do you call this type of growth?

Ans8.
Auxetic growth.


Q9. Why is the cleavage in
mammals referred to as simple holoblastic?

Ans9.
Cleavage in mammals is referred to as Simple Holoblastic because in
the absence of any Yolk in the mammalian egg, it divides completely. This means
the cleavage furrow divides the egg or blastoderms completely.


Q10. Name the tissue that lines
the urinary bladder. State any one advantage of this tissue being present there.

Ans10.
The urinary bladder is lined by Transitional Epithelium. The
advantage of having this stretchable tissue is that it may be considerably
stretched without getting torn when the bladder is filled with urine.



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