Discussion questions
1. Table 1 shows percentages by volume of some gases in inspired air, expired
air and alveolar air, in a resting human being.
Gas
Oxygen
Nitrogen
Carbondioxide
Water vapour
Inspired air
20.90
78.60
0.03
0.47
Percentage Volume (%)
Expired air
Alveolar air
15.30
13.90
74.90
No data
3.60
4.90
6.20
No data
Figure 1 a and b show effects of increased carbondioxide concentrations in
inspired air, on the volume of air breathed in and out per minute and on the
breathing rate respectively.
(a) Explain why
(b)
(i)
the percentage volume of oxygen in expired air is intermediate
between the inspired and alveolar values.
04 marks)
(ii)
there is a difference in the percentage volume of nitrogen
between inspired and expired air.
(i)
(04 marks)
using the information in figure 1, calculate the mean volumes of a
single breath in and out, at different carbondioxide concentrations in
inspired air, indicated in Table 2. (3 marks)
Table 2
1
Compiled by Milton Chebet. 2009 Gayaza High School
Percentage
concentration of
CO2 in inspired air
(ii)
(c)
0
1
2
3
4
+5
6
Plot a graph showing the mean volume of a single breath against
percentage concentration of carbondioxide in inspired air. (5½marks)
Describe the effect of the increase in carbondioxide concentration in inspired
air on the
(03 marks)
(i)
(ii)
(iii)
volume of air breathed in and out per minute
breathing rate
mean volume of a single breath in and out
(03 marks)
(03 marks)
(03 marks)
(d)
Explain the effect of the increase in carbondioxide concentration in inspired
air on the
(i)
volume of air breathed in and out per minute
(02 marks)
(ii)
breathing rate
(02 marks)
(iii) mean volume of a single breath in and out
(02 marks)
(e)
Outline the physiological effects in the body, of breathing in excess
(i)
carbondioxide
(04 marks)
(ii)
oxygen
(04 marks)
2. Two groups of maize seeds were germinated and grown in different culture
solutions. Group A were provided with a complete nutrient solution while
Group B were provided with a solution lacking magnesium. An extract of
photosynthetic pigments was made from leaves of each group of seedlings at
the end of three weeks. Figure 1 is the absorption spectra obtained from the
extracts.
2
Compiled by Milton Chebet. 2009 Gayaza High School
In another experiment, six identical shoots of pond weed were placed in
separate test tubes of pond water in which a dilute solution of sodium
hydrogen carbonate had been added. Each test tube was then exposed to light
which had passed through a different coloured filter. The light in all cases was
from a 40 watt bulb, placed 40 cm from the test tube. The time taken for 20
bubbles to leave the cut end of each shoot was recorded three times and the
average results are recorded in Table 1.
Table 1
Colour of filter
Violet
Blue
Blue-green
Green
Yellow
Orange-red
3
Average time taken to release
20 bubbles in seconds
58
40
62
132
96
70
Number of bubbles
released per minute.
Compiled by Milton Chebet. 2009 Gayaza High School
Use the information to answer the questions that follow:
(a)
Compare the light absorption by extract from Group A and that from Group
B across the light spectrum.
(8 marks)
(b)
(c)
Explain the light absorption across the light spectrum for each extract.
(9 marks)
How does a coloured filter affect light passing through it.
(1 marks)
(d)
(i)
Copy and complete Table 1, by calculating the number of bubbles
released by each shoot per minute.
(3 marks)
(ii)
Plot a graph to show the relationship between the colour of the filter
and the rate at which bubbles are released.
(6 marks)
(i)
Compare your graph with that in figure 1, and state the relationship
between the two;
(2 marks)
What conclusion can you draw from the relationship?
(2 marks)
(e)
(ii)
(f)
State what would be observed if the distance between the bulb and the test
tubes was gradually reduced. Explain your answer.
(4 marks)
(g)
Explain why
(i)
the type of bulb and the distance of the bulb from the test tubes were
kept constant.
(1 mark)
(ii)
a dilute solution of sodium hydrogen carbonate was added to pond
water in the test tubes.
(2 marks)
(iii) There were three measurements made on each shoot rather than a
single one.
(1 mark)
(iv)
Measuring the rate of photosynthesis by counting bubbles is not an
accurate method.
(1 mark)
3. Figures 1, 2 and 3 show the immigration and extinction of species on different
categories of virgin islands.
Figure 1 shows the rate of immigration of new species on an island nearby the
shore and one that is far from the shore.
Figure 2 shows the rate of extinction of species on a large island and on a
small island.
Figure 3 shows the rate of immigration and extinction of species on an island.
4
Compiled by Milton Chebet. 2009 Gayaza High School
Study the information and use it to answer the questions that follow.
Number of species
Rate of extinction of
species on island
Fig. 1
large island
Number of species
Fig. 2
5
Compiled by Milton Chebet. 2009 Gayaza High School
Rate of immigration and
extinction on an island
Number of species
Fig. 3
(a) Explain the rate of
(i)
immigration of new species on an island that is near to the shore and one that is
far from the shore ( figure 1 ).
(10 marks)
(ii)
extinction of species on a small island and on a large island
( figure 2 )
( 09 marks)
(iii)
immigration and extinction of species on an island.
( figure 3 )
( 07 marks)
(b)
From figures 1, 2 and 3 what conclusions can you draw about what determines the
number of species on an island?
( 05 marks)
(c)
Describe how factors other than those depicted in the information provided, may affect
the immigration of new species on an island.
(04 marks)
(d)
Suggest the factors that would cause immigration of new species to a virgin island.
( 05 marks)
6
Compiled by Milton Chebet. 2009 Gayaza High School
Solutions
1.
7
Compiled by Milton Chebet. 2009 Gayaza High School