Marking Scheme

Secondary

October - November, 2000

Subject : Science

Part -A

Maximum Marks 20

Q.No. Answers Q.No. Answers

Set A B C Set A B C

XXI/OS/O/2

21 28 30 A

22 27 29 B

23 26 28 B

24 25 27 C

25 24 26 B

26 23 25 A

27 22 24 C

28 21 23 C

29 30 22 B

30 19 21 A

31 18 40 D

32 17 39 D

33 40 38 A

34 39 37 D

35 38 36 B

36 37 35 B

37 36 34 C

38 35 33 D

39 34 32 C

40 33 31 B

1 16 10 C

2 15 9 C

3 14 8 C

4 13 7 D

5 12 6 A

6 11 5 B

7 10 4 C

8 9 3 B

9 8 2 C

10 7 1 D

11 6 20 B

12 5 19 A

13 4 18 A

14 3 17 A

15 2 16 D

16 1 15 C

17 32 14 D

18 31 13 B

19 30 12 B

20 29 11 B

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(½ mark for each correct answer)

PART -B

Maximum Marks : 65

Q. No Expected Value Points For dISTRIBUTION Total

A B C EAch Step OF MARKS

1 - - Liver 1 1

2 - - Root Crops 1 1

3 3 1 (i) Mass of the body (ii) Raised height , 1 4 2 5

1 1

5 1 4 Mica 1 1

6 - - Estimation, hearing, touching 1, 2

7 - -

1

= 5 m/s² 2

8 12 8 Photosynthesis is the process by which plants manufacture
their own food with the help of sunlight 1

Sunlight, chlorophyll, CO₂, H₂O 1 2

9 11 7 They provide energy for body processes 1

Fats 1 2

10 10 6 1. Easy to clean 2. Water and moisture proof 3. Protection
against variation in temperature and humidity 4. Safe from
possible sources of infection 5. Protection from entry of
rodents, birds etc. (Any four) 4×1/2 2

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11 9 14

Fig : 1

Labelling : 1

Fig. Silver Plating of spoon p.64/vol. 5 2

12 8 13 (i) : : (ii) 1,1 2

13 - - Benzene or phenol is converted into intermediate dye
by reaction with nitric and sulphuric acids. Finally dye is
obtained from its intermediate compund. 1

Alizanin 1 2

14 6 11 Computer conferencing enables participants to
communicate with one another by using computer
keyboard to transmit written messages. 1

Any two or more participants sit on their computer
terminals and exchange written messages between them. 1 2

15 - - Groups of stars forming patterns in the sky which can be
recognised are called Constellations 1

1

Great Bear/Big Dipper/Plouge 1 3

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16 - - Everybody continues in its state of rest or of uniform
motion in a staight line unless an unbalanced external
force acts on it. 1

Th feet in contact with the earth are suddently brought
to rest while the rest of the body due to inertia of motion
tends to move forward. Hence the man is thrown forward. 2 3

17 21 17

1

Oxygen tension becomes lower in tissues. Hence CO₂
dissociates from haemoglobin in RBC to diffuse in the
tissues. CO₂ tension is highest in the tissues and it diffuses
into the blood. CO₂ is carried to body parts. 1 3

18 - - (i) Ecosystm : The living organisam together with physical
environemnt of a region.

Example : Natural forest

(ii) Biome : All the ecosystems taken together in a
geographical area.

Example : pond, lake, grassland together making a forest
biomes.

(iii) Biosphere ; All the biomes world over taken together as
a bigger unit which is self sustaining biological system.

Example : life supporting regions of the earth. 3

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19 19 15 (a) Combustion is a chemical change in which heat and light
are produced at the same time 1

(b) Presence of combustible sustance, attainment of ignition
temperature, continous supply of supporter of combustion. 1

(c) (i) Burning of magnesium in nitrogen

(ii) Burning of sodium metal in chlorine 3

20 18 23 (a) Anaemia :

(i) Disease caused by deficiency of iron in the body

(ii) defeciency of haemoglobin in the red blood cells.

(iii) by eating food rich in iron and vitamine B₁₂. 3

(b) Goitre ;

(i) Abnormal enlargement of the thyroid gland situated in
our neck.

(ii) deficiency of iodine.

(iii) iodised salt with diet

21 17 22 (a) Oxidation is loss of electron while reduction is gain of
electrons. 1+1

(b) (i) Na is oxidised

(ii) Cl is reduced 3

22 16 21 Limestone, gypsum and clay. 1

The three chemicals are mixed in a definite ratio and
grinded to fine powder. The powder is mixed with water
to form a paste. This paste is heated in rotary kiln.
Gray coloured stone like chrinkers are found. This is
powdered and then 2-3% gypsum is added. 2 3

23 15 20 (a) (i) store the data (ii) control the sequence of operation
(iii) control, manage and coordinate the functions of all
units, (iv) data processing. 4×=2

(b) control unit. 1 3

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24 25 25

3

2

5

Fig . 20.4 Fertilization and Development p.71/vol.3

25 26 26

Fig. 31.7 page 86/vol. 5

(i) Labelled diagram 2

(ii) Construction : A rectangular loop of wire is wound on
an armature. The armature rotates around a spindle
between the poles of a magnet. The loop is connected to
split ring (commutator) 1

(iii) Working : When current is passed through the coil, the

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A B C EAch Step OF MARKS

magnetic field pushes loop down. This way a continuous 1
roration is produced.

(iv) Use : to convert electrical energy into mechanical energy. 1 5

26 - - (i) An optical instument used to see small objects by forming
their magnified images. 1

(ii) Erect and magnified virtual image 1

(iii) When the object is placed at a distance less than the
focal length of the convex lens an erect and magnifed 1
imeage is formed.

(iv)

2 5

Fig. 33.24 page 41/vol. (Image formation by simple
microscope)

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Part B

Note : New Questions for Set B

XXI/OS/O/2 B

Q. No Expected Value Points For dISTRIBUTION Total

B EAch Step OF MARKS

4 Auxin, Gibberellin, Cytokinin, Abscisic acid

(any one) 1 1

5 Persistalsis is movement of contraction by which food
moves down in stomach 1 1

7 F = ma

= 100 kg ×6m/s²

= 600 kg m/s² 1

= 600 N 2

13 In a paint the coloured powder is called a pigment, the
liquid that carries the pigment and makes it easy to spread
is known as binder +

Pigment : Titanium Dioxide

Binder : Varnish or latex 2

14 Order of magnitude of a number is the nearest power of 1
ten to which it is approximated. 2

or seven 1

20 Energy after being trapped by plants

(producers) is passed on the animals (consumer)of next
trophic level in the from of food. The amount of energy
available goes on decreasing during its transfer from one
trophic level to the next. At the level when decomposer
energy is relesed it is not availble for retrapping by the
plants. So the flow of energy through various trophic
levels is one way. 2

Example 1 3

22 i) Momentum of a moveing body is the product of its mass
and velocity. 1

ii) kg m/s² 1

iii) Rate of change of momentum = Force 1 3

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23 A star is a giant size mass of very hot glowing gases while
a planet is a heavently body revolving about a star. 2

Mercury, Venus, Earth, Mars, Jupiter, Sturan, Uranus,
Neptune, Pluto 1 3

a) a telescope is an optical instrument used to view the
distant objects 1

b) Two. Astronomical and Reflecting telescopes +

c) Reflecting telescope consists of a concave mirror as
objective whereas refracting telescope (astronomical)
consists of a convex lens as objective. 1

d) Refelecting telescope 1

1+1

e) Fig 33.26 Reflecting Telescope page 42 vol.6 5

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Part B

Note : New Questions for Set C

XXI/OS/O/2 C

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2 Fibre crops 1 1

3 Mitochondrial Cells 1 1

9 a = 1

1

2

10 A thermocouple is an instrument used to measure very
high and very low tepperatures or a thermocouple is made
of two. different metal wires connected to an ammeter. 1

Adventage : can measure very high and very low
temperatures. 2
Disadvantage : very expensive

12 Fertilizers are the chemicals used by farmers to get better
crop. 1
a) Urea, ammonium sulphate, ammonium nitrate.(any one)

b) super phosphate 2

l6 A food Chain is the repersentation of a single energy
pathway.

Grass------------Deer------------ Lion 1

A Food web is a network of species relationship formed
by interconnected food chains

Fig 21.2 page 5 1 3

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18 a) A body is said to move with uniform velocity if its
magnitude as well as direction both do not change with
time. 1

Example :

A Horse moving with a constant speed one direction.

b)

on multiplying (1) by (2)

2 as = (v - u) ( v + u)
2 as = v² - u²
2or v² - u² = 2 as 3

19

Fig. 11.5 page 34/vol.2 Luner Eclipse 1

Fig. 11.6 Page 34/vol. 2 Solar Eclipse 1

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Luner Eclipse occurs when the shadow of the earth fals
on the moon.

Solar Eclipse occurs when the shadow of the moon falls
on the earth masking the sun. 3

24 Labelled diagram

Fig. 32.21 Electric bell 2

Construction : The two ends of the winding of the
electromegnet are connected to the power supply through
make and break arrangement and push button. 1

Working : When the bell push is pressed, soft iron core
of the electromagnet and the hammer hits the gong. As
soon as the armature is attracted the current circuit breaks
and the armature is pulled back because of the spring
action. 1

i) Electromagnet : attracts the armature which hits the gong.

ii) Armature : performs make and break functions of the
electric current because of spring action. 5

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