S.
S. L. C. EXAMINATION, MARCH/APRIL, 2020
Subject
: SCIENCE ( Biology )
1. In the given figure of Cotyledon the
parts labelled as A and B respectively
(A) fruit, shoot
(B) primary shoot, primary root
(C) secondary root, primary shoot
(D) bud, leaf.
Ans. : (B) primary shoot, primary root
7. The incorrect statement related to thyroxine hormone among the
following is
(A) it regulates fat metabolism
(B) its deficiency leads to goitre
(C) it is secreted by parathyroid gland
(D) iodine in the food is essential for its production.
Ans. : (C) it
is secreted by parathyroid gland 1
1. “The rate of breathing in aquatic
organisms is much faster than that seen in terrestrial organisms.” Why ?
Ans.
: Because, the amount of dissolved oxygen is
fairly low compared to the amount of oxygen in the air.
14. The gene for brown coloured hair is recessive that of gene for black
coloured hair. What is the hair colour of a person who has inherited a gene for
brown coloured hair from mother and black coloured hair from father ?
Ans. : Black
coloured hair
18. “The body temperature of frogs and lizards depend on temperature in
the environment.” Justify. Ans. : 1. Both
frogs and lizards have three chambered heart
2. Oxygenated and deoxygenated
blood mix in the heart.
3. Production of energy became
slightly less. This energy cannot be used for maintaining constant
temperature.
21. “As
energy moves progressively through various trophic levels of food chain it is
no longer available to the previous level.” Give reasons.
Ans. : 1. The flow of energy in the food chain is
unidirectional.
2. The energy that is captured by
autotrophs does not revert back to the solar input.
3. The energy which passes to the
herbivores does not come back to autotrophs.
4. The energy available at each trophic level
gets diminished progressively due to loss of energy at each level.
5. 23. Draw the diagram showing the germination
of pollen on stigma and label the pollen tube.
Germination of pollen on stigma.
27. Explain the significant function of each structure in human male
reproductive system. OR Explain the structure and important role of placenta
during gestation period of woman.
Ans. : i) Testis : They produce sperms and testosterone hormone
which is responsible for male characters.
ii) Scrotum : They regulate temperature necessary for
production of sperms.
iii) Urethra and vas deferens
: Transport sperm from testis.
iv) Prostate gland and seminal
vesicle : They add their secretion to
make the sperm transport easier and provide nutrition.
v) Penis : Delivers the sperms to the site of
ferliziation.
OR
1. During pregnancy period the embryo gets
nutrition from the mother’s blood with help of disc shaped special tissue
embeded in the uterine wall is called placenta.
2. It
contains villi on the developing side of the tissue.
3. Villi provide glucose and oxygen to pass from
mother to embryo.
4. Removes the wastes generated from the embryo.
29. “Building crescent shaped
earthen embankment in level terrain is better than the construction of large
dams across the river to store water.” Analyse this statement with their
effects.
Ans. : 1. Social problems : Effects of the construction
of large dams across the rivers
2. Economic problems : Swallop up huge
amount of public money.
1
Environmental problems : They contribute
enormously to deforestation and loss of biological diversity.
Advantages of building crescent shaped earthen
embankement in level terrain :
1. They recharge the ground water beneath.
2. Water does not evaporate, but spreads out
recharge wells and provide moisture for vegetation
3. It does not provide breeding grounds
for mosquitoes like stagnant water collected in ponds ( OR ) lakes.
34. Name the given structure. What is its
general function ? Mention the function of the parts labelled as A and B. These
structures in animals are said to be efficient ways to give quick responses.
Why ?
Ans. :
1. Reflex arc
2. It
gives sudden action in response to the event happening in the environment.
A) Sensory neuron : It conducts the impulse of stimulus from receptor
to the spinal cord.
B)
Effectors : Which shows the sudden visible response.
Reflex arcs have evolved in animals because the
thinking process of brain is not fast enough in many animals. Mean while many
animals have very little of the complex neuron network needed for thinking. So
it can function in the absence of true thought process and increase the chance
of survival.
37. The plant bearing round yellow coloured (
RrYy ) seed are self pollinated with the same plant. Represent the result
obtained in the 2 F generation of dihybrid cross with the help of a checker
board. Mention the varieties of plants obtained in 2 F generation. OR What is
evolution ? Explain the three evidences for evolution.
Phenomenon
of gradual change of organisms from simple form into complex form in a long
period is called evolution. 1 Three evidences are : i) Homologous organs : The organs which have same basic structures
but modified to perform different functions are called homologous organs.
Provide the information that organisms of
different species might be evolved from common ancestor.
ii) Analogous organs : The organs which have different basic
structures but they perform similar function are called analogous organs.
Provide the information that though the
organs of different organisms perform same function, they may not have same
function but they may not be evolved from common ancestor. 2 1
iii) Fossils :
1. The dead remains of past organism under the rocks/deep earthen layers
are called fossils. 2. They help to study evidence and missing link
between different species.
3 They help
to understand the sequence of evolution and help in classification of organisms.
( Any one point )
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