Previous Year Paper year:2012 : ICSE-X-Biology

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ICSE-X-Biology

Previous Year Paper year:2012

with Solutions - page 6

#4-b-ii
Allele
Ans : Allele - It is one of the alternative form of the same gene responsible for determining contrasting characteristics.

#4-b-iii
Pulse
Ans : Pulse - It is a wave of pressure of blood passing through the arteries as it is pumped out of the heart.

#4-b-iv
Reflex action
Ans : Reflex Action : It is a spontaneous, automatic, involuntary response to a stimulus.

#4-b-v
Synapse
Ans : Synapse : It is the point of contact between the axon endings of one neuron with the dendrites of the other neuron through where the impulse is transmitted from one neuron to the other.

Qstn #5
:

#5-a [5]
Study the diagram given below and then answer the questions that follow :

#5-a-i [5]
Name the part labelled A. Name any two hormones produced by the part labelled A.
Ans : A - Ovary: Two hormones are :
(1.) Oesterogen
(2.) Progesteron

#5-a-ii
What happens to the part labelled B :
(1) If fertilisation takes place ? (2) If fertilisation does not take place ?
Ans : (1) If fertilisation takes place, part B i.e. uterus gets prepared to receieve the embryo. The endometrial lining thickens and gets highly vascularised.
(2) If fertilisation does not take place part B, then the endometrial lining of uterus erodes causing bleeding i.e., menstruation.

#5-a-iii
Where does fertilisation occur ?
Ans : Fertilisation occurs in the fallopian tube/oviduct.

#5-a-iv
Draw a neat diagram of the human sperm as seen under high magnifi-cation and label the following parts.
(1) Acrosome (2) Mitochondria
Ans :

#5-b [5]
A homozygous plant having round (R) and yellow (Y) seed is crossed with homozygous plant having wrinkled (r) and green (y) seeds :

#5-b-i
Give the scientific name of the plant on which Mendel conducted his hybridization experiments.
Ans : Pisum sativum

#5-b-ii
Give the genotype of the F₁ generation.
Ans : Genotype of the F₁ generation Rr Yy

#5-b-iii
Give the dihybrid phenotypic ratio and the phenotype of the offspring of the F₂ generation when two plants of the F₁ generation are crossed.
Ans : Ratio of F₂ generation 9:3:3:1 Phenotypes of F₂ generation are:
1. Round and yellow 2. Round and green
3. Wrinkled and yellow 4. Wrinkled and green

#5-b-iv
Name and state the law which explains the dihybrid ratio.
Ans : Law of Independent Assortment.