S4 Analytical Questions


  1. The table below shows how the concentration of carbon dioxide ( CO2) in savannah grassland varies over a period of fourteen hours.
Carbon dioxide concentration (%) 0.055 0.045 0.03 0.03 0.03 0.035 0.05 0.06
Time (Hours) 8:00am 10:00am 12:00pm 2:00pm 4:00pm 6:00pm 8:00pm 10:00pm

(a) Using an appropriate scale use the data in the table above to plot a graph

(b) Using the graph estimate the concentration of carbon dioxide at 9:00am, 3:00pm and 7:00pm 1 1/2marks

9:00am                                                  3:00pm                                                 7:00pm

(c)Describe the trend of the graph plotted above;

(d)Explain the shape of the graph;

(e) State one process that increases and reduces the rate of carbon dioxide in the atmosphere

(f) State the changes in the concentration of oxygen in savannah grass land over the period of 14 hours.

2. The table below shows the changes in the dry weight of seedlings during the first 6 week of germination.

Time(weeks) 0 1 2 3 4 5 6
Dry weight(g) 75 50 38 25 40 80 150

a ) Plot this information as a graph in the space below.(8 marks)

b) With reference to the graph describe the change in dry weight over the period of 6 weeks. (2 marks)

c) Explain the change in dry weight. ( 2 marks)

c)On the same graph draw another graph if fresh weight was considered.Label the two graphs to differentiate them.( 1 mark).

d) Explain why the graph appears as it is shown.(1 mark)

e) Why is it advantageous to measure growth of an organism using fresh weight instead of dry weight?(1 mark)

c)Why is it disadvantageous to measure growth of an organism using fresh weight instead of dry weight?(1 mark)

e) What other two methods apart from use of weight can be used to measure the growth of a plant?(1 mark)

f) Suggest three factors that can affect the growth of a plant.(1 ½ Marks)

g) For each of the factors mentioned, state one of its roles in the growth of a plant. .(1 ½ Marks)

3.In an investigation, two persons A and B drank the same amount of a glucose solution. Their blood sugar levels were determined immediately and thereafter at intervals of one hour for the next six hours. The results were as shown in the following table.

  Blood glucose level (mg/100ml)
Time (hours) Person A Person B
0 90 120
1 220 360
2 160 370
3 100 380
4 90 240
5 90 200
6 90 160


  • Use same axes to present the information in the table graphically.
  • Give reasons(s) for each of the following observations.
  • Blood sugar level increased in person A between O and 1 hour
  • The blood sugar level decreased in person A between 1 and 4 hours
  • From the graph, what is the normal blood sugar level for human being?
  • Suggest a reason for the high sugar level in person B.
  • How can the high blood sugar level in person B be controlled?
  • What is the biological significance of maintaining a relatively constant sugar level in the human body?
  • Give reason for the decrease in the blood sugar level of person B after 4 hours.

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