What do understand by i) respiration ii) fermentation iii) breathing iv) gaseous exchange? Describe the mechanism by which oxygen is taken into the lungs and carried to the muscles of the leg. Describe an experiment to show that carbon dioxide is produced during the respiration of germinating seeds.

Here are the answers to the questions from SECTION IV: RESPIRATION, GASEOUS EXCHANGE AND BREATHING.

1a) What do understand by i) respiration ii) fermentation iii) breathing iv) gaseous exchange?

• i) Respiration: This is the biochemical process within living cells where organic substances, primarily glucose, are broken down to release chemical energy, which is then stored in ATP molecules. It can occur with (aerobic) or without (anaerobic) oxygen.
• ii) Fermentation: This is an anaerobic metabolic process that converts sugars into acids, gases, or alcohol. It occurs in the absence of oxygen, typically in microorganisms like yeast and some bacteria, and also in animal muscle cells during intense activity.
• iii) Breathing: This is the physical process of moving air into and out of the lungs. It involves the mechanical actions of inhalation (taking air in) and exhalation (expelling air), driven by the contraction and relaxation of respiratory muscles like the diaphragm and intercostals.
• iv) Gaseous exchange: This is the process by which gases, specifically oxygen and carbon dioxide, move across a respiratory surface (like the alveolar-capillary membrane in the lungs) by diffusion, from an area of higher partial pressure to an area of lower partial pressure.

1b) Describe the mechanism by which oxygen is i) taken into the lungs and ii) carried to the muscles of the leg.

• i) Oxygen taken into the lungs (Inhalation):