Question
(a) Fig. 5.1 shows a graph of the human population from 1800 to 2010.
The human population before 1800 had remained fairly constant.
(i) Suggest three reasons for the increase in the human population since 1800.
(ii) State three social implications if the human population continues to increase at the
current rate.
(b) Many human activities cause pollution of the environment.
Describe the undesirable effects of the following pollutants.
Answer/Explanation
Ans:
Question
(a) Increasing human population is linked to a change in carbon dioxide concentration in the
atmosphere. Fig. 4.1 shows the carbon dioxide concentration between 1958 and 2010
measured at Mauna Loa, Hawaii.
Describe how the carbon dioxide concentration has changed between 1958 and 2010.
You will gain credit for using data from Fig. 4.1 [3]
(b) (i) Carbon dioxide is a greenhouse gas.
Name one other greenhouse gas. [1]
(ii) Explain how carbon dioxide enhances the greenhouse effect. [3]
(c) Mineral ions are needed for plant growth.
Complete Table 4.1 to show the function and effect of the lack of some mineral ions on plants.
One has been done for you.
(d) Fertilizers can cause pollution to aquatic systems. Overuse of fertilizers may cause
eutrophication. Lake Udai Sagar in India is an example of an aquatic system that shows high
levels of eutrophication.
Explain what happens in aquatic environments, such as Lake Udai Sagar, when eutrophication
occurs. [6]
[Total: 17]
Answer/Explanation
Ans
4 (a) 1 overall carbon dioxide concentration increases ;
2 at a steady rate ;
3 there are minor fluctuations in carbon dioxide concentration ;
4 the fluctuations occur, regularly / yearly / seasonally ;
5 use of comparative figures with year and concentration with units ;
(b) (i) methane ;
(ii) 1 radiation/ light from the Sun hits, Earth/ atmosphere ;
2 (named) short-wave radiation passes through carbon dioxide layer ;
3 re-radiated/reflected, from the ground as long-wave radiation/ infrared/ heat
energy ;
4 long-wave radiation/ infrared/ heat energy, trapped/ prevented from escaping
from atmosphere by carbon dioxide ;
(c) 
(d) 1 fertiliser/ nutrients, leached into/enter, rivers / streams / lakes ;
2 causing algal bloom/ algae growth ;
3 algae block sunlight from entering water ;
4 so rooted plants unable to photosynthesise ;
5 so plants die ;
6 bacteria, decompose/feed, on dead plants ;
7 so bacterial population increase ;
8 bacteria respire aerobically ;
9 bacteria use up the oxygen in the water ;
10 organisms / fish/ creatures, die/ suffocate/ migrate, due to lack of oxygen ;