Answers

Chapter : Respiration

STRUCTURED QUESTIONS

1.  X :        C₆ H₁₂ O₆   +  6 O₂                      6 CO₂  + 6 H₂O  +  Energy

     Y :        C₆ H₁₂ O₆                          2 C₂ H₅ OH  +  2 CO₂  +  Energy

The equation X and Y above  shows the reaction that occurs in the respiratory process.

a) State the type of respiration represented by equation

i)                    X: Aerobic respiration.

ii)                  Y: Anaerobic respiration in plants.

b)   i)  Define the process X   

                Aerobic respiration is the oxidation of glucose to release energy in the presence

                of oxygen.

ii) Define the process Y

                 Anaerobic respiration is the process where by glucose is broken down to

                 release energy in the absence of (without using) oxygen).

c)      Anaerobic respiration  yields less energy compared with aerobic respiration.

      State  the reason for this.

      Glucose is broken down completely in aerobic respiration. In anaerobic  

      respiration glucose is not broken down completely but partially to give lactic acid

      or ethanol and carbon dioxide. Some of the energy is still stored in the lactic

      molecule and ethanol molecule.     

d)     A person who does strenuous exercise experiences “ oxygen debt”. Explain what is meant by “ oxygen debt”.

The condition known as oxygen debt arises when the lactic acid accumulates in the muscle tissue as a result of an anaerobic respiration. This causes the person to feel tired because of muscle fatigue. Inhalation of oxygen when resting oxidizes the lactic acid to release energy, water and carbon dioxide. When this occurs the oxygen debt is said to have been paid.

e)      Write an equation for (d).

C₆ H₁₂ O₆        →      2C₃ H₆ O₃   +  Energy


7.3 Gaseous Exchange

1. Alveolus

2. The concentration of oxygen in the structure X is higher than that in the blood.

3. a) Its spherical shape provides a large surface area

    b) The alveolus wall is only one cell thick so that diffusion of gases can occur easily.

    c) The moist surface of the alveolus makes the gases dissolve in this fluid and diffuse

        across the walls easily

    d) It is covered with blood capillaries that makes the transport of gases to and from the

        alveoli more efficient.

       (Any two)

4. Gas A = oxygen

    Gas B = carbon dioxide

5. Diffusion

6. Hemoglobin

7. Oxyhaemoglobin

8. A) Bicarbonate ions

    b) Carbaminohaemoglobin

    c) Carbonic acid

9. Bicarbonate ions

10. It is higher in the alveolus.