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Science 2 Marks Questions

Respiration in Organisms · Gujarat Board (GSEB) STD 7 (GSEB - English Medium). 26 questions.

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26 questions · timed · auto-graded

Question 12 Marks
Boojho has seen in television programmes that whales and dolphins often come up to the water surface. They even release a fountain of water sometimes while moving upwards. Why do they do so?
Answer
Whales and dolphins come up to the water surface and release a fountain of water sometimes while moving upwards. This is because they tend to breathe the fresh air and eject carbon dioxide along with the water. The hole that ejects water is called a 'blow hole'. When they expell the air out of it, it appears like a fountain of water.
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Question 22 Marks
Given below is a model showing mechanism of breathing?
Image
(a) Did you see any changes in the balloons?
(b) What do the balloons in this model represent?
(c) What does the rubber sheet represent?
Answer
(a) Yes, balloons deflate when we push the rubber sheet up.
(b) Balloons in this model represent lungs.
(c) Rubber sheet represents diaphragm.
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Question 32 Marks
Can you say in which activity the rate of breathing will be the slowest and in which it will be the fastest?
Image
Answer
While sleeping, the rate of breathing will be the slowest and while doing strenuous physical activity like dancing the rate of breathing will be fastest.
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Question 42 Marks
Paheli wants to know why we yawn when we are sleepy or drowsy?
Answer
We yawn when we feel sleepy or drowsy to increase oxygen intake and promote alertness. Yawning helps to bring in more oxygen and expel carbon dioxide.
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Question 52 Marks
When you feel drowsy, does your breathing rate slow down? Does your body receive sufficient oxygen?
Answer
When we feel drowsy, sleepy or tired, we yawn (i.e., open our mouth wide to take a long and deep breathe) because our breathing rate slows down and our body does not receive sufficient oxygen.
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Question 62 Marks
Boojho noticed that when he released his breathe after holding it for some time, he had to breathe heavily. Can you tell him why it was so?
Answer
When Boojho released his breathe after holding it for some time, he had to breathe heavily in order to supply extra oxygen to his body to make up for the oxygen which was unavailable during the time when he held his breathe.
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Question 72 Marks
We get relief from cramps after a hot water bath or a massage. Can you guess why it is so?
Answer
Accumulation of excess lactic acid in the muscles causes pain and leads to muscles fatigue (cramp). We can get relief from muscle cramps by taking a hot water bath or massage.
This improves the circulation of blood and therefore, oxygen supply to the muscle cells of affected area increases. The increased supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water, thereby giving relief from cramps.
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Question 82 Marks
Have you even wondered why you get muscle cramps after heavy exercise?
Answer
In human body, when muscles are overworked, e.g. during exercise, the oxygen demand is not met through aerobic respiration. Thus, muscle cells begin to respire anaerobically in low oxygen conditions due to which glucose gets converted into lactic acid.
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Question 92 Marks
Observe the figures carefully and answer the following questions.
Image
(i) Which process is being tested in the activity?
(ii) What is the result of the activity? Give reasons.
Answer
(i) Exhalation process of respiration is being tested in the activity.
(ii) The lime water in test tube B turns milky but water in test tube A remains unchanged. This is because CO2 is present in the exhaled air, which mixes with lime water in test tube B and turns it milky.
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Question 102 Marks
Observe the given figures labelled as A and B and answer the following questions.
Image
(i) Among both figures identify which $A$ or $B$ indicates the process of inhalation and which shows the process of exhalation?
(ii) In the figure label the arrows and Indicate the direction of
(i) movement of air
(ii) movement of diaphragm
(iii) movement of ribs
Answer
(i) Figure A indicates inhalation and figure B indicates exhalation.
(ii) Movement of air, diaphragm and ribs are indicated in below figure
Image
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Question 112 Marks
Pick the odd one out from each of the groups given below on the basis of respiratory organs. Give reason for your answer.
(a) Cockroach, grasshopper, snail, ant
(b) Lizard, cow, earthworm, snake
(c) Crocodile, whale, dolphin, fish
(d) Snake, tadpole, crow, goat
Answer
(a) Snail, as it does not breathe by means of trachea.
(b) Earthworm, because it breathes through its skin and it does not have lungs.
(c) Fish, as most fishes breathe through their gills and do not have lungs.
(d) Tadpole, as it breathes through gills and do not have lungs.
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Question 122 Marks
All organisms breathe in $O _2$ and breathe out $CO _2$.
Should not there be less $O _2$ and excess of $CO _2$ in our environment.
Answer
All organisms breathe in $O _2$ and breathe out $CO _2$. The $CO _2$ released by us is used by plants during the process of photosynthesis and they release $O _2$. This maintains a balance between $O _2$ and $CO _2$ in the atmosphere.
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Question 132 Marks
Respiration can occur in two different manners. Briefly explain the process of aerobic respiration. How does it differ from anaerobic respiration?
Answer
Aerobic respiration is the process in which glucose is completely broken down in the presence of oxygen to produce carbon dioxide, water, and a large amount of energy.
It differs from anaerobic respiration because anaerobic respiration occurs without oxygen, produces less energy, and forms substances like alcohol or lactic acid instead of carbon dioxide and water.
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Question 142 Marks
Whenever we feel drowsy or sleepy, we start yawning. Does yawning help us in anyway?
Answer
Yes, yawning helps us by increasing the intake of oxygen and removing excess carbon dioxide from the blood.
It also helps to refresh the brain and make us more alert.
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Question 152 Marks
Name one organism which respires anaerobically. How does this organism help in beverage and baking industry?
Answer
Yeast is an organism that respires anaerobically.
It helps in the beverage and baking industry by producing alcohol and carbon dioxide during anaerobic respiration, which is used in making alcoholic drinks and to make bread rise
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Question 162 Marks
Insects and leaves of plant have pores through which they exchange gases with the atmosphere. Can you write two points of difference between these pores with respect to their position, number and extension into the body?
Answer
Pores present on the sides of insects are called spiracles while pores present on the surface of leaves are called stomata. These structures are responsible for the exchange of gases with the atmosphere.
Differences between these two are as follows
(i) Spiracles are fewer in number as compared to stomata.
(ii) Spiracles lead to an extensive network of tracheal system which is absent in the leaves.
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Question 172 Marks
Whales and dolphins are seen many times releasing a fountain of water at the surface of water. Why do they do so?
Answer
Animals like dolphins and whales live in sea water, but unlike fishes, they do not possess gills for respiration. They have nostrils which are called blow holes. These blow holes are located on the upper parts of their heads. These animals breathe in through their nostrils and lungs.
Dolphins and whales come to the surface of sea water at intervals to breathe in air. Sometimes whales release a fountain of water that moves upwards like a spray.
It can be seen from many miles away. Blow holes are surrounded by muscles that keep the holes closed when the animal is under water and opens them when the animal is at the surface and needs to breathe.
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Question 182 Marks
There are three animals named A, B and C. Among them A can stay on land as well as in water. When it stays at land it respires through lungs, but when it goes into water, it respires through its moist skin. Animal B has specific organs to respire in the water which is not found in any other water animal. While animal C is a water animal which respires through nostrils and lungs. Now give the names of animal A, B and C.
Answer
Animal A can live on land as well as in water and can respire through lungs as well as moist skin. The animal is frog.
Animal B lives in water and respires through a specific organ called gills. The animal is fish.
Animal C is also an aquatic animal which lives in water and respires through nostrils and lungs, but not by the gills. The animal is whale.
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Question 192 Marks
On a very cold morning, Boojho and Paheli were talking with each other as they walked down to their school. They observed that the air coming out of their mouth looked like smoke. They were amazed and wondered how it happened. Help them to find the answer.
Answer
On a cold day, the warm and moist air exhaled by us condenses into mist when it comes in contact with the cold air of the atmosphere. This look like white smoke.
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Question 202 Marks
Observe the given diagram of human respiratory system. List the organs from A to G.
Image
Answer
The human respiratory system has the following organs
A - Ribs
B - Trachea
C - Pharynx
D - Diaphragm
E - Lungs
F - Nasal passage
G - Oral cavity
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Question 212 Marks
After we work hard or perform physical activity, we feel hungry. Explain why?
Answer
When we work hard or perform a physical activity (like running, swimming, cycling), we need more energy. To fulfill the energy requirement, we breathe faster. Fast breathing helps in the supply of more oxygen to our cells. Due to this, rate of breakdown of food increases and more energy is released. The rapid breakdown of food makes us feel more hungry.
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Question 222 Marks
What happens when breathe is released after holding for a few minutes? Give reason for its occurrence.
Answer
Releasing breathe after holding it for some time results in rapid breathing. It occurs to maintain a healthy balance between intake of $O _2$ and release of carbon dioxide.
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Question 232 Marks
List the similarities and differences between aerobic and anaerobic respiration.
Answer
Similarities between aerobic and anaerobic respiration are as follows
(i) Both processes involve the breakdown of glucose.
(ii) Release of energy takes place in both processes.
(iii) $\text{CO}_{2}$ is the common product in both processes.
Differences between aerobic and anaerobic respiration:
Aerobic respirationAnaerobic respiration
It occurs in the presence of oxygen.It takes place in the absence of oxygen.
Complete breakdown of food takes place in aerobic respiration.Partial breakdown of food occurs in anaerobic respiration.
End products of aerobic respiration are $\text{CO} _2$ and water.End products of anaerobic respiration are alcohol and $\text{CO} _2$ or lactic acid.
Large amount of energy is produced during aerobic respiration.
e.g. humans, dogs, etc.		Less amount of energy is produced during anaerobic respiration.
e.g. yeast.
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Question 242 Marks
Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer
Our body needs energy to perform all activities. While doing heavy exercises like running, demand for energy increases. Hence, more oxygen is required to meet this requirement. Therefore, an athlete breathes faster and deeper than usual after finishing the race.
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Question 252 Marks
What is the difference between breathing and respiration?
Answer
Breathing is the process of inhaling oxygen and exhaling carbon dioxide through the lungs. Respiration is the chemical process in cells in which glucose is broken down to release energy.
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Question 262 Marks
Respiration can be classified into two types. Name them and explain in brief.
Answer
In aerobic respiration, oxygen is used to break down glucose into carbon dioxide and water, releasing energy.
In anaerobic respiration, glucose is broken down without oxygen, producing less energy along with substances like alcohol or lactic acid.
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