1. Give one main difference between: (1X2=2)
a. Breathing and respiration
b. Aerobic and anaerobic respiration.
2. Explain the mechanism of breathing in humans. (3)
Give reason for the following statements:
a. Our body cells require oxygen. (1)
b. Fish die when kept outside water, even though there is oxygen in the surrounding air. (1)
5. How do frogs breathe on land and in water? (2)
6. a. State one main difference between respiration in humans and respiration in plants. (1) b. Mention any one similarity common to respiration in humans and respiration in plants (1)
Answers
1.
a) Breathing and respiration are two completely different but interrelated body processes that assist body organs to function properly. Breathing is the physical process of exchanging gases whilst respiration is a chemical process that takes place at a cellular level and produces energy.
b) Aerobic respiration takes place in presence of oxygen; whereas anaerobic respiration takes place in absence of oxygen. Carbon dioxide and water are the end products of aerobic respiration, while alcohol is the end product of anaerobic respiration. Aerobic respiration releases more energy than anaerobic respiration.
2.
Breathing is the physical process of inhaling oxygen and exhaling carbon dioxide. The mechanism of breathing involves two main processes: inspiration and expiration. Inspiration occurs when the diaphragm and the external intercostal muscles contract. Expiration occurs when the diaphragm and the intercostal muscles relax. The contraction or relaxation of muscles around the lungs changes the entire volume of air inside the lungs, and so does the pressure. If the pressure inside the lungs is more than the outside, the air rushes out. If the opposite happens, the air rushes in. Due to the high elasticity of the lung tissue and low surface tension of moisture in the lungs, the lungs have higher compliance.
3.
a) Cells need oxygen to be able to carry out that process. As every cell in our body needs energy, every one of them needs oxygen. The energy released is stored in a chemical compound called adenosine triphosphate (ATP), which contains three phosphate groups.
b) When fishes are taken out of the water, the supply of oxygen to the fishes is cut as the fishes cannot absorb and breathe using the oxygen present in the atmosphere. Hence, they die after some time.
5.
In water, frogs exchange gases through its thin, moist and smooth skin which is richly supplied with blood capillaries. On land, frogs breathe through their lungs.
6.
a) In plants, respiration uses oxygen to release energy from stored sugar and produces carbon dioxide as a byproduct.
b) Both plants and humans produce energy from respiration.