(a) (i) What is respiration?
(ii) In a tabular form, state four differences between gaseous exchange and aerobic respiration
(b)(i) Explain the term residual air.
(ii) What is the importance of residula air to mammals?
(c) State four characteristic features associated with respiratory structures.
(d)(i) What is oxygen debt?
(ii) Outline three activities that can result in oxygen debt.
Explanation
(a) (i) Respiration: Respiration is the process by which living things breakdown/oxidise food/nutrients/glucose/ organic substances; to release energy/ATP for metabolic activities of the body; with or without the use of oxygen.
| Gaseous exchange | Aerobic respiration |
| oxygen is used to oxidise glucose | organism and CO² moves out |
| process takes place outside the cell | process occurs inside the cell |
| physical process | chemical process |
| No energy is released | energy is released |
| No enzymes involved | enzymes involved |
(b) (I) Residual Air: During breathing out/expiration/exhalation; not all the air is removed from the lungs; the air left inside the lungs during breathing out is residual air.
(ii) Importance of Residual Air: Air is left in the lungs so that the lungs do not collapse; air is always left inside the lungs so that more oxygen can be removed (diffuse) into the blood stream.
(c) Characteristic features of respiratory structures: -
- They have wide/large surface area
- they are moist
- thin walled membranes
- they are highly vascularised/ richly supplied with blood
- highly permeable to gases.
(d)(i) Oxygen debt: The build up of lactic acid; during strenuous exercise is poisonous and makes the muscles ache; oxygen is needed to break down/ get rid of the lactic acid, that is why athletes continue breathing heavily even after the exercise is over; the oxygen needed to get rid of the lactic acid is known as oxygen debt.
(ii) Activities that can result in oxygen debt: Running; boxing; swimming /any correct example of strenuous activities.