09 Gep Sb 3 Resp

Maris Stella High School GCE O Level Science Biology GEP LESSON 3

Name: ___________________ Class (Index No.): Sec 4__ ( ) Date: ________________

Respiration 1.

The diagram below shows an experiment that measures the volume of air he breathed out. The volume of the exhaled air can be measured by means of the markings on the plastic bottle.

A sample of the exhaled air was taken out and analyzed. The results are shown in the table shown below. Volume of sample taken out for analysis Volume of sample after the absorption of carbon dioxide Volume of sample after the absorption of both carbon dioxide and oxygen

10.0 cm3 9.6 cm3 8.0 cm3

a.

Name the gas that occupies a large proportion of the volume of the exhaled air.

b.

Suggest a chemical substance that could be used in the above analysis for the absorbing of carbon dioxide. [1]

c.

In the sample of exhaled air taken out for anaylsis, what was the percentage of

d.

i. carbon dioxide, and

[1]

ii. oxygen?

[1]

[1]

If the person were to perform the above experiment again shortly after vigorous exercise, state the change in the volume of the exhaled air. [1]

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2.

The two graphs (figure 2) show the oxygen uptake and the lactic acid concentration in the blood of a man before, during and after a short period of physical exercise.

Figure 2 (a)(i) Explain the increase in lactic acid concentration in the blood at the beginning of exercise. [2]

(ii)

Write a word equation for the production of this lactic acid. [1]

(b)(i) State the biological term used to represent the shaded area on graph A. [1] (ii) Explain why the volume of oxygen in the shaded region is related to the amount of lactic acid in the blood. [2]

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(c)(i) Describe the effect of lactic acid during exercise. [1]

(ii) Suggest why this lactic acid is not excreted out of the body? [1]

(d)

3.

Name another organism, besides the human being, which produces lactic acid and explain why the organism produces it. [1]

The diagram (figure 3.1) shows an alveolus.

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Figure 3.1 (a)

Describe 2 adaptive features of the alveolus and explain how they are related to the efficient diffusion and transport of oxygen. [2] 1.

2.

The graph (figure 3.2) shows some of the changes that take place in a man during breathing.

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Figure 3.2 (b) (i) Use the information in the graph to calculate this man’s rate of breathing in breaths per minute. Show your working. [1]

Answer ............................................................. (ii) The volume of air in the man’s lungs after he had exhaled was 2400 cm3. What is the volume of air in his lungs immediately after he had inhaled? [1]

(c) Not all the air that a person breathes out has been in the alveoli. Explain why. [1]

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Respiration GEP lesson 3 1(a) (b) (c) (d)

Answer Scheme

Nitrogen (1) gas calcium/ sodium/ potassium hydroxide (1) i. (10 – 9.6)/10 = 4% (1) ii. (9.6 – 8)/10 = 16% (1) The volume of exhaled air increases (1).

2(a) (i) Oxygen cannot be delivered to the muscles fast enough to keep pace with the need. Cells respire anaerobically producing lactic acid which accumulates and diffuses into the blood stream. (ii) Glucose  lactic acid + small amounts of energy (absence of oxygen) (b) (i) Oxygen debt (ii) Lactic acid is toxic to the body cells and needs to be oxidised to glucose. The required volume of oxygen shown by the shaded region to oxidised lactate (c) (i) It causes muscle fatigue (ii) It contains a large amount of unutilised energy which would be lost if excreted. (d) Any ONE situation there is absence of oxygen in muscles. e.g. Animals living in stagnant water (worms); Parasites in our gut (tapeworm); mammals which dive for long periods (whales, seals); muscles of any named mammal during strenuous activity. 3(a) 1. Walls are one-celled thick so that gases can diffuse across easily/quickly. 2. Alveoli are surrounded by a network of capillaries to transport oxygen and carbon dioxide. 3. Presence of a thin film of moisture on the alveolus for diffusion of gases (b)

(i) From 60/3.5 to 60/3 = 17-20 breaths per minute (working/units must be shown) (ii) 2880cm3

(c) Some air has been in the trachea/bronchi and will never reach the alveoli.

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