Chapter No. 1 - Gaseous Exchange - Short Question Answers

 

Biology For Class X - Chapter No. 1 - Gaseous Exchange - Short Question Answers

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CHAPTER 1: GASEOUS EXCHANGE
B. Short Questions Answers

i) Why the stomata generally open during day-time?
Ans: The stomata control gas exchange in the leaf. Each stoma is surrounded by two guard cells . The stomata can be opened or closed, depending on how turgid its guard cells are. In the light, during the on going process of Photosynthesis the guard cells absorb water by osmosis , become turgid and thus the stoma opens. In the dark, the guard cells lose water, become flaccid and the stoma closes.

ii) Which parts of the plant intake CO₂ and give out O₂ , take in O₂ oxygen and give out CO₂ during day-time?
Ans: Plants take in CO₂ and give out O₂ during the process of Photosynthesis in the day time . Photosynthesis occurs because of the green parts of the plant ,mainly leaves. Therefore leaves are responsible for taking in CO₂ and giving out O₂. While on the other hand the taking in of O2 and giving out CO₂ happens during the process of respiration in the night time. Exchange of gases during respiration involves roots and stem of the plant.

 
iii) Why do we have to breathe through nostrils rather than oral cavity?
Ans: It is better to breathe through nostrils rather than oral cavity because the entire passage of nasal sacs through which air passes is lined by mucous secreting ciliated cells. The hairs in nasal sacs as well as ciliated epithelial lining and mucous keep the air clean by trapping and removing dust and germs. This ensures clean air to approach the respiratory surface. On the other hand oral cavity has no medium to filter air and it also makes the mouth dry.

iv) Why do we deep breathe during or immediately after exercise?
Ans: We deep breathe during and immediately after exercise because Exercise increases the rate of breathing due to the increased consumption of oxygen by muscles. It gradually increases the concentration of carbon dioxide in blood and will cause an increase in breathing rate. If the exercise condition persists, the muscle cells will start breaking down Glucose without oxygen. As a result of this, lactic acid is formed in the muscles rather than carbon dioxide. The breaking down of lactic acid requires additional amount of oxygen. The extra amount of oxygen is obtained through deep breathes. 

 

iv) Differentiate between breathing, gaseous exchange and respiration.
Ans: Difference Between Gaseous Exchange, Breathing And Respiration

S.NO.	Gaseous Exchange	Breathing	Respiration
1.	Gas exchange is the physical process by which gases move passively by diffusion across a surface.	Breathing involves inhaling oxygen and exhaling carbon dioxide.	Respiration involves the process wherein the oxygen is used to break the glucose into energy to be later used by the cells of the body.
2.	Gaseous exchange in plants is done through photosynthesis.	Breathing happens (occurs) in the lungs.	Respiration takes place in the cells of the body.
3.	The gaseous exchange in animals involves breathing.	Breathing is a physical process.	Respiration is basically a chemical process.
4.	It involves the movement of gases from a surface of higher concentration to a surface of lower concentration.	During breathing, there is no energy production.	Energy is produced during the respiration process in the form of ATP
5.	Aquatic organisms exchange gases with water while terrestrial ones with air.	It is an extracellular process as it takes place outside the cells.	This is basically an intracellular process that takes place in the cells.
6.	In plants gaseous exchange is done through stomata in the leaves.	Enzymes are not in use at the time of breathing.	Enzymes are used in large numbers.
7.	In animals gaseous exchange is done through alveoli in lungs.	Breathing occurs due to the nose, lungs, etc.	Cells, mitochondria- cell organelles carry out the process of respiration.

v) Why do we deep breathe during or immediately after exercise?
Ans: We deep breathe during and immediately after exercise because Exercise increases the rate of breathing due to the increased consumption of oxygen by muscles. It gradually increases the concentration of carbon dioxide in blood and will cause an increase in breathing rate. If the exercise condition persists, the muscle cells will start breaking down Glucose without oxygen. As a result of this, lactic acid is formed in the muscles rather than carbon dioxide. The breaking down of lactic acid requires additional amount of oxygen. The extra amount of oxygen is obtained through deep breathes.

vi) What is "oxygen debt"?
Ans: During exercise condition the muscle cells start breaking down Glucose without oxygen. As a result of this , lactic acid is formed in the muscles rather than carbon dioxide. The breaking down of lactic acid requires additional amount of oxygen. That extra amount is called oxygen debt and is obtained through deep breathes.

vii) Distinguish between inspiration and expiration.
Ans: Difference Between Inspiration And Expiration

S.NO.	INSPIRATION	EXPIRATION
1.	Inspiration is the intake of the air into the lungs.	Expiration is the expulsion of the air out of the lungs.
2.	Inspiration is an active process.	Expiration is a passive process.
3.	In inspiration, the external intercostals muscles are contracted and internal intercostals muscles are relaxed.	In expiration, the external intercostals muscles are relaxed and internal intercostals muscles are contracted.
4.	In inspiration, rib cage moves forward and outward.	In expiration, the rib cage moves downward and inward.
5.	In inspiration, the diaphragm contracts and flattens.	In expiration, the diaphragm relaxes and becomes original dome shaped.
6.	In inspiration, the size of the thoracic cavity increases.	In expiration, the size of the thoracic cavity decreases.
7.	In inspiration, the air pressure in lungs is less than the atmospheric pressure.	In expiration, the air pressure in the lungs is higher than the atmospheric pressure.

viii) What is lung cancer?
Ans: LUNG CANCER:
Lung cancer is a respiratory disease, more common in men than women.

Causes:

1. Smoking
2. Industrial carcinogens
3. Air pollution

Main cause of any cancer is a carcinogen, ionizing radiation, and viral infection. Smoking is the main contributor to lung cancer. Cigarette smoke contains over 69 known carcinogens. Due to smoke or air pollution, abnormal cells appear in lungs which may spread to other tissues.

Symptoms:

1. Cough with sputum
2. Breathlessness (shortness of breath)
3. Pleural chest pain
4. Repeated Lung infections
5. Weight loss
6. Bone ache
7. Hoarseness
8. Weakness
9. Fatigue etc.

In the early stages, lung cancer does not show any symptoms. However, in the advanced stage when it has fully spread, it is very painful and incurable and becomes fatal.

Treatment:
The patient of lung cancer is given one or more treatments, including:

• surgery
• chemotherapy and
• radiation therapy

ix) How the asthma is characterized?
Ans: Asthma is an inflammatory condition of air-ways of lungs. It is characterized by:

1. shortness of breath
2. chest pain
3. fever
4. wheezing sound during expiration and cough.

Asthma is actually an allergic response to pollens, dust, smoke, fur, feathers and number of other substances. It may obstruct the air-ways making it difficult to breath for its patient.

x) Name five animals which use their body surface for gaseous exchange.
Ans: The animals which use their body surface for gaseous exchange are:

1. Flat worms
2. Earthworms
3. Leech
4. Sabella
5. Tapeworm