The city School
PECHS Junior Boys
Revision Worksheet # 1
Science Grade: 7
Topics: Forces, Microorganisms
Q1. Encircle the correct answer.
i)
___________________ attacks on bacteria.
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a. Fungi
b. Influenza virus
c. Bacteriophage
ii)
Hosts provide ___________ to their parasites.
a. nutrients
b. microorganisms
c. warmth
iii)
_______________ is the microorganism that keeps on changing its shape.
a. Amoeba
b. Rotifer
c. Paramecium
iv)
The air resistance acts in the opposite direction to the _____________.
a. frictional force
b. weight
c. upthrust
v)
The weight of an object is the _________________ acting on it.
a. lift
b. gravitational force
c. air resistance
Q2. Identify the force acting in each case.
i)
ii)
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A moving ball stops. __________________________
A ball falls towards the ground when thrown upwards. ________________
iii)
Compass needle points at north. ______________________
iv)
A parachutist falls slowly to the ground. ______________________
v)
An object weighs less in water than in air. _____________________
Q3. Differentiate between weight and mass.
Weight
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Mass
Q4. Identify the causative agent of the following diseases.
i)
Athlete’s foot diseases. _______________________
ii)
Malaria. _________________________________
iii)
Gum diseases. _____________________________
iv)
Dengue fever. _____________________________
Q5. Give scientific reason as to why;
a) food stored in refrigerator takes long to rot or spoil.
________________________________________________________________
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________________________________________________________________
b) a dead animal and its waste seem to disappear over time.
________________________________________________________________
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c) adding yeast to dough makes the bread rise.
________________________________________________________________
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________________________________________________________________
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Q5. Mr. Ahmed applied force on a toy truck and get the following result.
a)
Why do you think truck stays still?
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_________________________________________________________________
_________________________________________________________________
b) What should he do to move it to the right?
/1
_______________________________________________________________
_______________________________________________________________
Q6. Human intestines are habitats for different microorganisms. Give two benefits
of the microorganisms in our body.
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Ans. _____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Q7. It is said that microorganisms are friends of us, with the help of following figures
state how are they beneficial for us?
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a)
b)
a. ________________________________________________________________
b. ________________________________________________________________
Q8. Write any two preventive measures against infectious diseases.
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Ans: 1._____________________________________________________________
2.______________________________________________________________