Practice Sheet – 2 (2017-18) Grade: VII sub science ( solved)

PODAR INTERNATIONAL SCHOOL

Practice Sheet – 2 (2017-18)

Grade: VII

Subject: Science Answer Scheme Duration: 1 ½ hours

1 mark questions
1. Define the term wind current.
ans: Wind current is the movement of air from one place to another.
(Ch 10: Forces of Nature, pg 114)
2. Explain the term polyatomic molecules.
ans: Molecules containing more than two atoms of an element is known
as a polyatomic molecule.
(Ch 6: Inside matter, pg 67)
2 mark questions
3. Explain the role of small intestine and large intestine in the process of
digestion in human beings.
ans:  The main function of small intestine is of mixing and digesting
the chyme from the stomach, production of enzymes necessary
for digestion of food and absorption of nutrients.
 The main function of large intestine is to absorb excess water
and necessary salts from the contents received after digestion in
small intestine.
(Ch 3: How Animals get energy, pg 29)
4. Classify the following examples into the given categories- natural
acids and mineral acids
formic acid, hydrochloric acid, ascorbic acid, nitric acid
ans: natural acids mineral acids
ascorbic acid, formic acid hydrochloric acid, nitric acid
(Ch 7: The Chemical Rainbow, pg 81)
CB/VII/1718 Practice Sheet – 2 page 2 of 5
5. a. Define the natural calamity
shown in the picture.
ans: It is a kind of weather in which lightning and thunder are usually
accompanied by heavy rains.
b. Which place is the best to stay during the occurrence of the natural
calamity shown in the picture above?
ans: The best place to stay during a thunderstorm is indoors with all the
doors and windows shut.
(Ch 10: Forces of Nature, pg 115)
6. Give reasons for the following statements.
a. Regions with higher temperature have more humidity.
ans: When the air in a region gets heated, it expands and holds more
moisture. Therefore, the regions with higher temperature have more
humidity than cooler regions.
Chapter 9: Changes and Adaptation, pg 96)
b. Most animals in the rainforests are able to camouflage.
ans: Most animals in the rainforests are brightly coloured, this helps
them to hide or camouflage in the green forest.
(Chapter 9: Changes and Adaptation, pg 101)
3 mark questions
7. Distinguish between:
criteria physical change chemical change
ans: products
formed
no new products are
formed
new products are formed
changes
observed
there is no change in
the identity of the
substance (matter)
undergoing change
new product(s) formed
show(s) different
properties than the one
we started with
reversibility most physical changes
are reversible
most chemical changes
are irreversible
(Ch 9: Changes and Adaptation, pg 106)
CB/VII/1718 Practice Sheet – 2 page 3 of 5
8. Draw a neat labelled diagram of a typical prokaryotic cell. Label the
following in the diagram.
pilli, flagellum, ribosomes, DNA
ans:
(Ch 1: Cells- the Building Blocks of Life, pg 4)
9. Write the names of animals from which the following types of fibres
are obtained.
a. shahtoosh
ans: chiru antelope
b. angora wool
ans: angora rabbit
c. mohair
ans: angora goat
(Ch 4: Fibres from Animals, pg 35, 36)
10. Sameer started mixing a strong acid and strong base in a test tube
without the knowledge of the teacher. He was also not wearing the safety
gears to be used in the science laboratory. His friend Krish warned him
not to use the chemicals without the knowledge of the teacher, as this
might be risky.
a. Why is it risky to use strong acids or bases without caution?
ans: Strong acids and bases are corrosive in nature, they can cause
some serious problems if exposed directly to the human body
b. Which values did Krish exhibit?
ans: Alertness, care for fellow beings, obedience towards rules, etc.
(Ch 7: The Chemical Rainbow, pg 76)
pilli
ribosomes
flagellum
DNA
CB/VII/1718 Practice Sheet – 2 page 4 of 5
11. Match the actions given in column A with the appropriate
instruments given in column B:
column A column B
a. checking fever i. laboratory thermometer
b. checking the boiling point ii. six’s thermometer
c. Maximum and minimum
temperature of a city for the
weather report
iii. anemometer
iv. clinical thermometer
ans: a.- iv, b.- i, c.- ii
(Ch 5: Heat and its Transfer, pg 50)
5 mark questions
12. Observe the picture and answer the questions:
a. Explain the adaptation of the animal that helps it to survive in the extreme
climatic conditions of its habitat.
ans:  The polar bears are huge in size; this helps them to keep the
body warm in extreme cold climate.
 The hairs on its body are transparent, thus, helping it to
camouflage in the snow.
 The hair on the bear’s body are also hollow, thus they trap air.
This helps the animal to stay warm and provides the buoyancy
while swimming.
 It has a thick layer of fat called blubber under the skin, this layer
protects it from the extreme cold.
 The paws of a polar bear are covered with papillae that allow the
animal to walk on ice and snow without slipping.
(Ch 9: Changes and Adaptation, pg 103)
CB/VII/1718 Practice Sheet – 2 page 5 of 5
13. Write the steps involved in an experiment to show that chlorophyll is
necessary for photosynthesis.
ans:  Expose the plant to strong sunlight for a few hours.
 Remove a leaf and sketch the leaf mapping the distribution of
green parts.
 Extract the pigments by boiling the leaf in alcohol / ethanol.
 Pour some iodine solution on the leaf to check for the presence
of starch.
 Sketch the leaf again, outlining the areas showing a positive test
for starch.
(Ch 2: Plant Diet, pg 10)
2 mark questions (Practical skill based questions)
14. If the valency of calcium is 2 and chloride is 1. Write the chemical formula
for the compound formed by combining the two elements.
ans: CaCl2
(Ch 6: Inside matter, pg 68)
15. State the evidence of chemical reactions in the following.
a. small piece of sodium metal placed in cold water
ans: produces hydrogen with a hissing sound
b. burning of log of wood
ans: release of heat
(Chapter 8: The Science of Change, pg 87)
16. Identify the type of nutrition, if an organism has feeding habits as
stated below.
a. An association in which the organism derives all the nutrition from the
host and also harms the host.
ans: Parasitic type of nutrition
b. An association in which the organism derives nutrition from dead organic
matter.
ans: Saprotrophic nutrition
(Ch 3: How Animals get energy, pg 20, 21)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>