SCIENCE ANSWER TO REVISION BANK TERM 1

 

PODAR INTERNATIONAL SCHOOL

Revision Question Bank 1 (2021-22)

Std: VII 

Subject: Science

Section A
1. Neha added a few drops of red cabbage indicator to a test tube containing
vinegar.
Which of the following changes will be observed in the colour of the red
cabbage indicator?
1
(a) The red colour of the indicator changes to pink.
(b) The red colour of the indicator changes to green.
(c) The purple colour of the indicator changes to red.
(d) The purple colour of the indicator changes to green.
ans: (c) The purple colour of the indicator changes to red. 
Ch 5: Acids, Bases and Salts, Pg 75
2. Which of the following statement/s is/are true?
Statement 1: The formation of a precipitate is the indication of a chemical
reaction.
Statement 2: When a cake is baked it releases heat.
1
(a) Only statement 1 is true.
(b) Only statement 2 is true.
(c) Both statements 1 and 2 are true.
(d) Neither statement 1 and nor statement 2 are true.
ans: (a) Only statement 1 is true. 

Ch 6: Physical and Chemical Changes, Pg 91
3. The part labelled as ‘X’ in the given diagram of the respiratory system of a
grasshopper represents:
1
(a) trachea
(b) spiracle
(c) operculum
(d) nostril
ans: (b) spiracle R
Ch 9: Respiration in Organisms, Pg 143
X

4. Study the given passage and answer the following question. 1
A distance-time graph is a way of representing the motion of an object in
the form of a graph. The given distance-time graph illustrates how far a car
moved and how long it took to reach that far.
How much distance was covered by the car in 30 minutes?

(a) (b) (c) (d) ans:

48 km 54 km 40 km 60 km (b) 54 km

Ch 12: Motion and Time, Pg 206
CB/VII/2021-22 Revision Question Bank-1 Page 4 of 7
5. Study the given passage and answer the following question. 1
A distance-time graph is a way of representing the motion of an object in
the form of a graph. The given distance-time graph illustrates how far a car
moved and how long it took to reach that far.
Which of the given statement/s best describes this graph?
I. The car covered equal intervals of distance in equal intervals of time.
II. This graph is an example of a non-uniform motion.
(a) Only I
(b) Only II
(c) Both I and II
(d) Neither I and nor II
ans: (b) Only II 
Ch 12: Motion and Time, Pg 206

Section B

6. (a) For question number (i) and (ii), two statements are given- one
labelled Assertion (A) and the other labelled Reason (R). Select the
correct answer to these questions from the codes (I), (II), (III) and (IV)
as given below:

(I)	Both A and R are true, and R is correct explanation of the assertion. Both A and R are true, but R is not the correct explanation of the assertion.
(II)

(III) A is true, but R is false.
(IV) A is false, but R is true.

(i)	Assertion: Arteries have thick walls. Reason: Arteries contain blood flowing under high pressure.

1
ans: (I) Both A and R are true, and R is correct explanation of
the assertion.

Ch 10: Transportation in Plants and Animals, Pg-153
(ii) Assertion: A wasp’s sting can be neutralised with baking
soda.
Reason: A wasp’s sting is basic in nature.
1
ans: (IV) A is false, but R is true. 
Ch 5: Acids, Bases and Salts, Pg- 80
(b) (i) How many ATP molecules are released in aerobic respiration? 1
ans: 38 
Ch 9: Respiration in Organisms, Pg-141
(ii) Name any two metals that can be mixed with iron to make
stainless steel.
1
ans: carbon/ chromium/ nickel/ manganese (any two) 

Ch 6: Physical and Chemical Changes, Pg-95
(iii) Name the thick, vertical muscular wall that divides the heart
into two parts.
1
ans: Septum 
Ch 10: Transportation in Plants and Animals, Pg-154
7. A bus starts at 5 am. It travels with a speed of 30 kilometres for the first
hour, and then travels with a speed of 40 kilometres for the next hour. Find
its average speed.
2
ans: Given:
Total distance covered = 30 + 40 = 70 km
Total time taken = 1 + 1 = 2 hours
To find out: Average speed =?
Average speed = 1 mark
= = 35 km/h 1 mark
Average speed of the bus is 35 km/h

Ch 12: Motion and Time, Pg- 205
8. Give reason for the following statements: 3

(a)	The opening of the left atrium into the left ventricle is guarded by the bicuspid valves.

ans: The opening of the left atrium into the left ventricle is guarded
by the bicuspid valves to prevent the backflow of oxygenated
blood into the left atrium.
1 mark
Ch 10: Transportation in Plants and Animals, Pg-155

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
(b) White blood cells are called soldiers of the body.
ans: White blood cells are called soldiers of the body as they
encounter a pathogen, engulf the organism and destroyit.
1 mark
Ch 10: Transportation in Plants and Animals, Pg-152
(c) It is necessary to remove waste products from the body.
ans: It is necessary to remove waste products from the body so as to
help maintain internal chemical homeostasis and prevent
damage to the body.
1 mark
Ch 10: Transportation in Plants and Animals, Pg-158
9. (a) Define the following. 5
(i) Reactants R/U
ans: The original substances that take part in a chemical reaction and
change into new substances are known as reactants.
1 mark
Ch 6: Physical and Chemical Changes, Pg 90
(ii) Physical change
ans: A change in which a substance undergoes a change in its
physical properties without the formation of a new substance is
called a physical change.
1 mark
Ch 6: Physical and Chemical Changes, Pg 87
(b) State three ways used to prevent rusting.
ans:  Galvanisation
 Application of oil, grease or paint
 Alloying
3 marks
Ch 6: Physical and Chemical Changes, Pg 95