(a) When sneezing, you should cover your nose so that the particles expelled by you would not be inhaled by others.
(b) Yes.
(c) No, it is process to remove/clear the particles harmful for us resulting in clean, fresh air to enter the lungs.
(d) Cleanliness and hygiene maintenance.

Releasing breathe after holding it for sometime results in rapid breathing. It occurs to maintain a healthy balance between intake of O2 and release of carbon dioxide.

Frog breathe by their moist skin and through lungs also. So, they do not have any, respiratory issue.
When frog enters into water, the skin of frog helps in respiration.
The oxygen rich air enters through the skin. When the frog is on land, a pair of lungs helps in respiration.
The lungs take the oxygen-rich air through the nostrils from where the oxygen is absorbed by the blood and carried throughout the body. The carbon dioxide from the blood is diffused back through the skin and lungs into the atmosphere.

When we inhale dust-laden air, dirt-particles are captured within the nostrils. Sometimes, they get past the nostril hair in the nasal cavity and irritate the lining of the cavity, as a result, we sneeze. Sneezing expels these foreign particles from the inhaled air and a dust free, clean air enters in our body

Our body needs energy for all activitie, while doing heavy exercises like running and there is a larger demand of energy to perform these activities. Hence, more oxygen is required to meet extra demand of energy. Therefore, an athlete breathes faster and deeper than usual after finishing the race

Move downwards During exhalation the ribs moves downwards causing a decrease in area of chest cavity forcing the air out.

Spiracles In cockroaches, air for respiration enters through small tubes/holes present on then body called spiracles.

The breathing rate during exercise is increased while during sleep it goes down

Frogs respire through their moist skin as well as through a pair of lungs

The various organs in the respiratory system of human are nostrils, nasal passage, nasal cavity, windpipe and lungs.

The end product formed during anaerobic respiration in yeast are
(i) Ethyl alcohol
(ii) Carbon dioxide
(iii) Energy

During aerobic respiration, carbon dioxide and water are released along with a large amount of energy.
\(glucose\overset { { O }_{ 2 } }{ \longrightarrow } { O }_{ 2 }+water+Energy\)

(a) Smoking is very injurious for the respiratory system. It harms lungs.
(i) It causes blockage in the respiratory tract.
(ii) It leads to lung cancer.
(iii) It can cause disease like asthma and heart diseases.
(b) Yes, smoking affects people who are passive smokers, i.e. those present nearby smokers.
(c) Yes, the people should bot smoke in public areas as it can cause discomfort to others. The values we understand are obedience, respect elders and healthy habits.

(a) Paheli had cramps in her leg muscles after running. She felt pain in her legs because of accumulation of lactic acid in the leg muscles. Lactic acid is formed due to anaerobic respiration in the muscle cells after heavy exercise or running. After heavy exercise, we require large amount of energy.
To produce more energy to meet the oxygen requirement of muscles, muscle cells perform anaerobic respiration for a short duration. Lactic acid is formed due to partial breakup of glucose. It gets accumulated in the muscle cells and causes pain and muscle cramps.
(b) The massage or hot water bath gives the relief from muscle cramp or pain, because it improves the circulation of blood leading to increase supply of oxygen to the muscle cells . It helps in complete breakdown of lactic acid into carbon dioxide and water