Class-7 Science Chapter-10 Respiration in Organisms, Additional Exercises in line with NCERT book / CBSE Syllabus


Chapter 10
Respiration in Organisms
Exercises from textbook
Additional Exercises
Activities/Projects
Additional Exercises

Choose the correct answer:
1-    Which of the following activity damages lungs and is linked to cancer
a.    Breathing
b.    Running
c.     Smoking (√)
d.    Yoga
2-    What is the percentage of Oxygen and Carbon dioxide in inhaled air
a.    21% oxygen & 0.04 % carbon dioxide (√)
b.    100 % Oxygen & No carbon dioxide
c.     50% oxygen  & 50% carbon dioxide
d.    16.4% oxygen & 4.4% carbon
3-    What is the percentage of Oxygen and Carbon dioxide in exhaled air
a.    21% oxygen & 0.04 % carbon dioxide
b.    100 % carbon dioxide & No oxygen
c.     50% oxygen  & 50% carbon dioxide
d.    16.4% oxygen & 4.4% carbon (√)
4-    Which of the following organism does not have lungs in its chest cavity?
a.    Lizard
b.    Birds
c.     Snake
d.    None of the above (√)
5-    Which of the following organ is present in the chest cavity
a.    Lunch (√)
b.    Stomach
c.     Kidney
d.    Gallbladder
6-    The number of times a person breathes in a minute is termed as
a.    Heart rate
b.    Pulse beat
c.     Breathing rate (√)
d.    None of the above
7-    A breath means
a.    one inhalation plus two exhalation.
b.    one inhalation plus one exhalation. (√)
c.     Two inhalations plus one exhalation.
d.    one inhalation only
8-    Which of these animal has trachea or air tubes for exchange of gases
a.    Cockroach (√)
b.    birds
c.     frogs
d.    lizards
9-    Which of the following statement is true about frogs?
a.    They have a pair of lungs
b.    They breathe through their skin
c.     Both a and b
d.    All the above

Fill in the blanks with suitable words:
1-    A cell is the smallest structural and functional unit of an organism.
2-    All living organisms respire to get energy from food.
3-    Breathing rate of an adult human being is 15-18 times per minute at rest.
4-    Our breathing rate changes according to the requirement of oxygen by the body.
5 
 Match the column:
A
B
Cutting
A part of stem/branch at which leaf arises
Node
A short stem around whihch immature overlapping leaves are folded.
Axil
A piece of branch with a node
Bud
Point os attachment of leaf at node.

Ans
A
B
Cutting
A piece of branch with a node
Node
A part of stem/branch at which leaf arises
Axil
Point os attachment of leaf at node.
Bud
A short stem around whihch immature overlapping leaves are folded.


State whether the following statements are True or False:

1-    Cellular respiration takes place in the cells of all organisms.            (True)
2-    During heavy exercise, the breathing rate can increase upto 25 times per minute. (True)
3-    During breathing inhalation and exhalation take place alternately (True)
4-    Air tubes or trachea are found in all groups of animals. (False)
5-   

Give one word for the following:

(a)  The production of new individual from their parents.
Reproduction
(b)  Mode of reproduction in which plants give rise to new plants without seeds.
Asexual Reproduction
(c)   Slimy green patches found in ponds or in other stagnetent water bodies.
Algae
(d)  The cell which results after fusion of the gamets.
Zygote

Encircle the Odd one:
1-    Nasal cavity, lungs, ribs, kidney, diaphragm (Organs involved in respiration)
2-    Elephant, lion, frog, cockroach, snake (lungs in chest cavity)
3-     

Differentiate between
(a)  Aerobic respiration and anaerobic respiration


Aerobic Respiration
Anaerobic Respiration
Aerobic respiration occurs in presence of oxygen.
An aerobic respiration occurs in absence of oxygen.
Aerobic respiration occurs in the mitochondria of cell.
Anaerobic respiration occurs in the cytoplasm of cell.
It produces high amount of energy.
It produces less amount of energy.
In aerobic respiration, glucose breaks down into carbon dioxide and water.
In anaerobic respiration, glucose breaks down alcohol and carbon dioxide.


Answer the following questions:

Q. What is cellular respiration? Why is it needed?
Ans- The air we breathe in is transported to all parts of the body and ultimately to each cell. In the cells, oxygen in the air helps in the breakdown of food. The whole process of breakdown of food in the cell with the release of energy is called cellular respiration.
Cellular respiration is needed to release energy from food.

Q. How does anaerobic respiration takes place in our muscles during heavy exercise, fast running, heavy weight lifting or cycling?
Ans- During heavy exercise, fast running, heavy weight lifting or cycling, the demand of energy in the body is high, but the supply of oxygen to produce the energy is limited. Then aerobic respiration takes place in the muscle cells to fulfill the demand of energy.


Q. How will you prove that the air we breathe out contains carbon dioxide?
Ans- Limewater Test-

 We will pour pour freshly prepared limewater in a test tube. Now we will blow air with the help of a straw. The change in the appearance of limewater (it turns cloudy) indicates that carbon dioxide is send in the air that we breathe out.

Q. Why do you sneeze? How does it help you get clean air?
Ans- We sneeze when some unwanted particles gets past the hair in the nasal cavity and it irritates the lining of the cavity.
Sneezing expel particles from the inhaled air and a dust free, air enters our body.

Q. How does the movement of ribs and diaphragm help in breathing?
Ans- Breathing involves the movement of diaphragm and Rib cage.
1-    During inhalation move up and outwards and diaphragm moves down. This increases space in our chest cavity and air crashes into the lungs.
2-    During exhalation, ribs move down and inwards, while diaphragm moves up to its former position. This reduces the size of the chest cavity and air is pushed out of the lungs.

Q. What is meant by breathing? Define breathing rate.
Ans- Breathing- Breathing means taken in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs.
Breathing rate- The number of times a person breathes in a minute is termed as breathing rate.
Q. Explain the breathing mechanism in insects.
Ans-
Insects have small openings called spiracles on the sides of their body. They have a network of tubes called trachea for exchange of gases. Oxygen rich air rushes through spiracles into tracheal tubes, diffuse into the body tissue and reaches every cell of the body.
Similarly, carbon dioxide from cells goes into the tracheal tubes and moves out through spiracles.

Q. How do fish breathe under water?
Ans- Fish have gills, which are feathery organs full of blood vessels.

Fish breaths by taking water into its mouth and forcing it out through the gill passages. As water passes through the thin walls of gills, dissolved oxygen moves into the blood and travels to fish’s cells.

Q. Do plants also respire? If yes, how do they respire?
 Ans- Yes, plants also respire to generate energy.

They have tiny pores called stomata for exchange of oxygen and carbon dioxide. Each part of plant can independently take in oxygen from the air and give out carbon dioxide. Roots of plants take up air from the air spaces present between the soil particles. plant cells use oxygen for breakdown of glucose into carbon dioxide and water like other organisms.

Give reason. Why?

Q. You get muscle cramps after heavy exercises.
Ans- After exercise, the cramps occur because during exercise our muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps.

Q. We get relief from cramps after a hot water bath or massage.
Ans- Hot water bath or massage improves circulation of blood. As a result, the supply of oxygen to the muscle cells increases. The increase in the supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water.

Q. You should cover while sneezing.
Ans- While Sneezing, we should cover our nose so that foreign particles we expel are not inhaled by other persons.

Q. You feel hungry after a physical activity.
Ans- During a physical activity, a person needs extra energy and he or she breathes faster. As a result, more oxygen is supplied to our cells. This speeds up the breakdown of food and more energy is released. Therefore, we feel hungry after a physical activity.

Exercises from Textbook
Q. Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans- During the race, there is need of more energy but the supply of oxygen is limited, so anaerobic respiration takes place in the body

After the race , an athlete breathe faster and deeper than usual to fulfill the demand of oxygen for the complete breakdown of lactic acid into carbon dioxide and water.

Q. List the similarities and differences between aerobic and anaerobic respiration.
Ans- Similarities
1-    Both are cellular respiration.
2-    Breakdown of glucose takes place in both.
3-    Both produce energy.
4-    Both consume oxygen.
5-    Both give out carbon dioxide..
Differences
Aerobic Respiration
Anaerobic Respiration
Aerobic respiration occurs in presence of oxygen.
An aerobic respiration occurs in absence of oxygen.
Aerobic respiration occurs in the mitochondria of cell.
Anaerobic respiration occurs in the cytoplasm of cell.
It produces high amount of energy.
It produces less amount of energy.
In aerobic respiration, glucose breaks down into carbon dioxide and water.
In anaerobic respiration, glucose breaks down alcohol and carbon dioxide.

Q. Why do we often sneeze when we inhale a lot of dust Laden air?
Ans- While we inhale, some unwanted particles such as smoke, dust, pollens etc. present in air are trapped by the hairs present in the nasal cavity.
Sometimes, these particles get past hair in the nasal cavity. There, they irritate the lining of nasal cavity, as a result we sneeze to get rid of these foreign particles.

Q. Take three test tubes. Fill three fourth of each with water. Label them A, B and C. Keep a snail in test tube A, a water plant in test tube B and in C keep snail and plant both. Which test tube would have the highest concentration of CO2?
Ans- Test tube A will have highest concentration of CO2 as the snail will release carbon dioxide as a byproduct of respiration.

Test tube B has water plant, which will release oxygen as a byproduct of photosynthesis.

Test tube C has both a snail and a plant of which one will release CO2 and the other will consume it.

Tick (√) the correct answer

1-    In cockroaches air enters the body through
a.    Lungs
b.    Gills
c.     Spiracles(√)
d.    Skin

2-    During heavy exercise, we get cramps in the legs due to the accumulation of
a.    Carbon dioxide
b.    Lactic acid(√)
c.     Alcohol
d.    Water

3-    Normal range of breathing rate per minute in an average adult person at rest is
a.    9-12
b.    15-18(√)
c.     21-24
d.    30-33

4-    During exhalation, the ribs
a.    Move outwards
b.    Movie downwards (√)
c.     Move upwards
d.    Do not move at all

Match the items in column 1 with those in column 2

Column 1
 Column 2
Yeast
 Earthworm
Diaphragm
 Gills
Skin
 Alcohol
Leaves
 Chest cavity
Fish
 Stomata
Frog
 Lungs and skin
  
 Trachea
Ans-
Column 1
 Column 2
Yeast
 Alcohol
Diaphragm
 Chest cavity
Skin
 Earthworm
Leaves
 Stomata
Fish
 Gills
Frog
 Lungs and skin
Cockroach
 Trachea

Mark T if the statement is true and F if it is false:
1-    During heavy exercise, the breathing rate of a person slows down. (F)
2-    Plants carry out photosynthesis only during the day and respiration only at night. (F)
3-    Frogs breathe through their skin as well as their lungs. (T)
4-    The fish have lungs for respiration. (F)
5-    The size of the chest cavity increases during inhalation. (T)

Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction - upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.


1) The air tubes of insects
2) Skeletal structures surrounding chest cavity
3) Muscular foot of chest cavity
4) Tiny on the surface of the leaves
5) Small openings on the sides of the body of an insect.
6) The respiratory organs of human beings
7) The openings through which we inhale
8) An anaerobic organism
9) An organism with tracheal system
Ans-


The mountaineers carry oxygen with them because
a.    At an altitude of more than 5 km there is no air
b.    The amount of air available to a person is less than that available on the ground (√)
c.     The temperature of air is higher than that in the ground
d.    The pressure of air is higher than that on the ground

Extended Learning - Activities and Projects

1 - Observe fish in an aquarium. You find flap like structures on both sides of their heads. These are flaps, which cover the gills. These flaps open and close alternately. On the basis of these observations explain the process of respiration in the fish.

2- Visit a local doctor. Learn about the harmful effects of smoking. You can also collect materials on this topic from other sources. You can take help of your teacher or parents. Find the percentage of people of your area who smoke. If you have a smoker in your family, confront him with the material that you have collected.
3- Visit a doctor . Find about artificial respiration. Ask the doctor
(a)  When does a person need artificial respiration?
(b)  Does the person need to be kept on artificial respiration temporarily or permanently?
(c)   From where can the person get supply of oxygen for artificial respiration?

4- Measure the breathing rate of the members of your family and some of your friends. Investigate:
(a)  If the breathing rate of children is different from that of adults.
(b)  If the breathing rate of males is different from that of females.
(c)   If there is a difference in any of these cases try to find the reason.

Did you know?
For us oxygen is essential but for those organisms, which do not use it oxygen is toxic. In fact for humans and other organisms, it may be dangerous to breathe pure air for long.



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