CLASS :- 7
SUBJECT :- SCIENCE
CHAPTER: - NUTRATION IN PLANT (NCERT Solutions)
Question
1.
Why do organisms need to take food?
Solution:
Food
is needed by all living organisms for the following purposes :
1. It is meant for the
general growth and development of an organism. If it is not an insufficient
amount, then it shows insufficient growth and development, along with hunger
signs.
2. It is meant to provide
energy. We need energy for movements such as running, walking, or raising our
arms.
3. It is also needed by
living beings for repairing of their damaged parts.
4. It gives us resistance
against diseases and protects us from infections.
Question
2.
Distinguish between a parasite and a saprotroph.
Solution:
|
Parasite |
Saprotroph |
|
(i) Parasite derives nutrients from living organisms.
|
They derive nutrients
from dead and decaying organisms |
|
(ii) Parasites mostly
live on or in the host |
They live on dead and
decaying stuff. |
Question
3.
How would you test the presence of starch in leaves?
Solution:
1. Take two healthy green
potted plants of the same kind in order to remove all the starch from the
leaves.
2. Keep one in the
darkroom (or in a black box) for 72 hours and the other in the sunlight.
3. Now, take one leaf
from each of the plants.
4. Put few drops of iodine
solution on each of the leaves.
5. The leaf kept in
the sunlight will turn blue-black due to the presence of starch.
6. The leaf kept in the dark
will not turn blue-black because of the absence of starch.
Question
4.
Give a brief description of the process of synthesis of food in green plants.
Solution:
In green plants, the synthesis of food occurs by a process called
photosynthesis. During photosynthesis, chlorophyll-containing cells of the
leaves, use carbon dioxide and water to synthesis carbohydrates in the presence
of sunlight. The process can be represented by an equation.
During this process, oxygen is released. The carbohydrates formed ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis. Starch is also a carbohydrate.
Question
5.
Show with the help of a sketch that the plants are the ultimate source of food.
Solution:
Question
6.
Fill in the blanks:
1. Green plants are called
………………. since they synthesize their own food.
2. The food synthesized by
the plants is stored as ……………….
3. In photosynthesis, solar
energy is captured by the pigment called ……………….
4. During photosynthesis
plants take in ………………. and release.
Solution:
1. autotrophs
2. starch
3. chlorophyll
4. carbon dioxide, oxygen.
Question
7.
Name the following:
1. A parasitic plant with
a yellow, slender, and tubular stem.
2. A plant that has
both autotrophic and heterotrophic modes of nutrition.
3. The pores through which
leaves exchange gases.
Solution:
1. Cuscuta
2. Pitcher plant
3. Stomata.
Question
8.
Tick the correct answer:
(a) Amarbel is an example of :
1. autotroph 2. parasite
3. saprotroph 4. host
(b) The plant which traps and
feeds on insects is :
1. Cuscuta 2. china rose
3. pitcher plant 4. rose
Solution:
(a)-2 parasite
(b)-3 pitcher plant
Question
9.
Match the items given in Column I with those in Column
II :
|
COLUMN :- I |
COLUMN :-
II |
|
Chlorophyll |
Bacteria |
|
Nitrogen |
Heterotrophs |
|
Amarbel |
Pitcher plant |
|
Animals |
Leaf |
|
Insects |
Parasite |
SOLUTION
|
COLUMN : -
I |
COLUMN :-II |
|
Chlorophyll |
Leaf |
|
Nitrogen |
Bacteria |
|
Amarbel |
Parasite |
|
Animals |
Heterotrophs |
|
Insects |
Pitcher plant |
Question
10.
Mark ‘T’ if the statement is true and ‘F’ if
it is false :
1. Carbon dioxide is
released during photosynthesis. (T/F)
2. Plants which
synthesise their food themselves are called saprotrophs. (T/F)
3. The product of photosynthesis
is not a protein. (T/F)
4. Solar energy is
converted into chemical energy during photosynthesis. (T/F)
Solution:
1. F
2. F
3. T
4. T
Question
11.
Choose the correct option from the following :
Which part of the plant takes in carbon dioxide from the air for
photosynthesis?
1. Root hair
2. Stomata
3. Leaf veins
4. Sepals
Solution:
2. Stomata
Question
12.
Choose the correct option from the following:
Plants take carbon dioxide from the atmosphere mainly through their:
1. roots
2. stem
3. flowers
4. leaves
Solution:
4. leaves
Class 7
Science
Chapter 6 Physical and Chemical Changes (NCERT
Solutions)
1 Classify
the changes involved in the following processes as physical or chemical
changes:
(a) Photosynthesis
Answer-chemical
changes
(b)
Dissolving sugar in water
Answer Physical
change
(c) Burning of coal
Answer chemical
changes
(d) Melting
of wax
Answer Physical
change
(e) Beating aluminum
to make aluminum foil
Answer Physical
change
(f )
Digestion of food
Answer chemical
changes
2. State
whether the following statements are true or false. In case a statement is
false, write the corrected statement in your notebook.
(a) Cutting
a log of wood into pieces is a chemical change. (True/False)
Answer false
(b)
Formation of manure from leaves is a physical change. (True/False)
Answer :-
false
(c) Iron
pipes coated with zinc do not get rusted easily. (True/False)
Answer :-
true
(d) Iron and
rust are the same substances. (True/False)
Answer:-
false
(e)
Condensation of steam is not a chemical change. (True/False)
Answer :-
true
3 Fill in
the blanks in the following statements:
(a) When
carbon dioxide is passed through lime water, it turns milky due to the
formation of ……calcium carbonate(CaCO3)….
. (b) The chemical
name of baking soda is ...........Sodium hydrogen carbonat
(c) Two
methods by which rusting of iron can be prevented are ………….painting ……. and ……….galvanisation…………
(d) Changes
in which only __.....physical……_____
properties of a substance change are called physical changes.
(e) Changes in which new substances are formed
are called _...chemical……__ changes.
4. When
baking soda is mixed with lemon juice, bubbles are formed with the evolution of
a gas. What type of change is it? Explain.
Answer :-
When baking soda is mixed with lemon juice, bubbles are formed with the
evolution of carbon di oxide (CO2)gas. This is chemical change .
Lemon
juice + baking soda → chemical substance + carbon di oxide
5. When a candle burns, both physical and
chemical changes take place. Identify these changes. Give another example of a
familiar process in which both the chemical and physical changes take place.
Answer : -When a candle burns, both physical
and chemical changes occur:
(i) Physical change: melting and
vapourisation of melted wax.
(ii) Chemical change: Burning of vapours of wax
to give a carbon dioxide
LPG is another example in which physical change
occurs
when LPG comes out of cylinderin the form of
liquid at high pressure and low temperature and when it used its converted from
liquid to gaseous state and a chemical change occurs when gas burns in air with
formation of carbon di oxide and water
6. How would
you show that setting of curd is a chemical change?
Answer :- We can say that setting of curd (sour
in test) from milk (sweet in test) is a chemical change because we can not get
the original substance, i.e., milk (sweet
in test )back and a new substance is formed with different taste, smell and
other chemical properties
7. Explain why burning of wood and cutting it
into small pieces are considered as two different types of changes
Answer :- Burning of wood in the presence of
air is a chemical change because in burning new substances are formed as
Wood + Oxygen ———–> Carbon dioxide + energy
But cutting it into small pieces is physical
change because no new substance is formed. We can only reduce the size of wood.
. 8. Describe
how crystals of copper sulphate are prepared.
Take a water(H2O) in a beaker and add some drops of dilute sulphuric acid (dil.H2SO4) and Heat the Solution . When it starts boiling, add copper sulphate(CuSO4) powder slowly. Continue to add copper sulphate (CuSO4) powder till no more powder can be dissolved. .During this process continuously stir the solution. After filtration Leave it for cooling. Look it after some time, you can see the blue colour crystals of copper sulphate (image with courtesy )
9. Explain
how painting of an iron gate prevents it from rusting.
Rusting of iron is a chemical process in the
presence of air and moisture . Painting stop rusting process because the iron gate from coming in contact with
oxygen and moisture.
10. Explain
why rusting of iron objects is faster in coastal areas than in deserts.
In the coastal
area moisture always in the air higher
than in the air in deserts. So, the process of rusting is faster in coastal
areas because air and moisture both responsible for rusting process .
11. The gas
we use in the kitchen is called liquified petroleum gas (LPG). In the cylinder
it exist as a liquid. When it comes out from the cylinder it becomes a gas
(Change – A) then it burns (Change – B). The following statements pertain to
these changes. Choose the correct one.
(i) Process – A is a chemical change.
(ii) Process
– B is a chemical change.
(iii) Both
processes A and B are chemical changes.
(iv) None of these processes is a chemical
change.
Answer (ii)
Process – B is a chemical change.
(Because
during burning process new substance formed)
12.
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The
biogas is then burnt as fuel (Change – B). The following statements pertain to
these changes. Choose the correct one.
(i) Process – A is a chemical change.
(ii) Process – B is a chemical change.
(iii) Both
processes A and B are chemical changes.
(iv) None of these processes is a chemical change
Answer (iii) Both processes A and B are chemical
changes.