iGCSE Biology (0610)-19.4 Populations – iGCSE Style Questions Paper 4

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 ;

Question

A researcher investigated the population growth of fish for fish farming. The researcher stocked a
    farmer’s lake with a small number of these fish and recorded the number of fish over the next five
    years. The researcher’s results showed that the population of fish had increased exponentially.

(a)  (i) Use the axes to show the exponential growth in the population of fish.
              Label the axes and draw a suitable curve.  

                 

      (ii) Explain why the population of fish increased exponentially.

Fig. 5.1 shows the total mass of wild fish caught worldwide between 1950 and 2012 and the mass
of farmed fish produced worldwide over the same period.

         

(b)  Describe the changes in the mass of wild fish caught between 1950 and 2012.
        You will gain credit if you use data from Fig. 5.1.

(c)  It is predicted that wild fish stocks will decrease and become depleted because of overfishing.
       Suggest ways in which governments can try to maintain the stocks of wild fish.

(d)  Like fish stocks, forests can be a sustainable resource.
        Discuss what is meant by the term sustainable resource, using forests as an example.

Answer/Explanation

Ans

5 (a) (i) vertical axis – numbers / population ;
               horizontal axis – time/ years ;
               curve showing exponential increase/ log phase ;

         (ii) idea that ‘birth’/reproduction/ breeding, rate is greater than death rate ;
                no limiting factors ;
                no/little, competition ;
                plenty, of food/nutrients / space/mates / oxygen/resources ;
                no/ few, predators ;
                no/ few, parasites / pathogens / disease ;
                AVP ; e.g. no / little, pollution/waste products / toxins

    (b) between 1950 and 2012
           mass of fish caught increased and levels off ;
           17 to 90 million tonnes / increase = 73 million tonnes ;
           fluctuations / increases and decreases / described ;
           e.g. around 1970/ any time after 1990 ;
           maximum catch, 94 million tonnes / in 1996 ;
           steep increase between, 1950–1970/ 1973–1989 ;

     (c) answers can refer to seas, lakes and
           /or rivers
            international, agreements /treaties ;
            quotas / permits / licenses ;
            fines / sanctions, for, overfishing/illegal/ unauthorised, fishing ;
            fishery protection vessels /wardens /patrols /AW ;
            restrictions on times when fishing can occur ;
            exclusion zones /nursery zones /‘no take’ zones /reserves ;
            total ban for some species ;
            regulations on method of fishing ;
            e.g. mesh size of nets / ban nets / use of lines instead/ size of
            fishing vessel/ ‘fishing effort’
            education/raise awareness / any example ;
            monitoring fish stocks ;
           captive breeding (of wild fish) ;
           re-stocking (of wild stocks) ;
           encourage farmed fish ; e.g. provide subsidies
           AVP ; e.g. tax on wild fish/ increase the cost of wild fish

   (d) definition of sustainable resource
          renewable/ self-renewing/regenerates / described ;
          e.g. produced as rapidly as it is removed
          resource, does not/will not, run out/ become exhausted ;
          replanting/reseeding/regrowing ;
          AVP ; e.g. pollarding/ coppicing/ leaving mature trees

Question

Carp are a type of fish. Researchers in Brazil measured the body lengths of a population of carp in
a river in 1998 and again in 2008.
Histograms of their results are shown in Fig. 2.1.

(a) Define the term population.
…………………………………………………………………………………………………………………………………
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(b) Describe the variation in body length of the carp population in 1998. Use the data in Fig. 2.1
to support your answer.
…………………………………………………………………………………………………………………………………
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(c) The total population of carp in 1998 was 43000 fish.
(i) Calculate the total population of carp in 2008.
Show your working.

(ii) The decrease in the carp population by 2008 was caused by overfishing.
Explain how fish stocks can be sustained.

………………………………………………………………………………………………………………………….
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(d) Body length is an example of continuous variation.
(i) Suggest what causes the variation in body length in a population of fish.

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………………………………………………………………………………………………………………………[2]

(ii) Continuous variation is shown with a histogram.
Name the type of graph that should be used to show discontinuous variation.
………………………………………………………………………………………………………………………[1]

Answer/Explanation

Ans:

Question

A study estimated the number of people with chronic obstructive pulmonary disease (COPD) in
    India. Data were collected from two groups of people, those who lived in cities and those who
    lived in villages.
    Fig. 2.1 shows the results.

     

(a) Compare the number of people with COPD in cities with the number of people with COPD in
       villages and suggest reasons for the differences.
       Use the data in Fig. 2.1 to support your answer.

(b) (i) Explain how the body prevents particles in inspired air from reaching the gas exchange
            surfaces.

      (ii) State two ways in which the composition of inspired air differs from the composition of
            expired air.
                   1 
                   2                                                                                                                                  [2]
(c) Alveoli are well-ventilated to provide efficient gas exchange.
      (i) State the name of the muscles that cause the ribs to move during ventilation.       [1]
     (ii) During inspiration the pressure and volume in the thorax changes.
            State these changes.
            pressure 
            volume                                                                                                                                      [1]
                                                                                                                                                  [Total: 14]

Answer/Explanation

Ans

2 (a) describe and compare
          1 COPD higher in villages than cities ; ora
          2 COPD increasing in both areas ;
          3 increasing more rapidly in villages ;
          4 fluctuation / COPD decreases, in cities in 2001 ;
          5 data quote comparing villages and cities including year and million ;
              suggest
          6 lack of healthcare in villages ;
          7 more people smoke in villages / passive smoking ;
          8 lack of awareness / education, in villages ;
          9 pollution in villages ;
          10 poor quality housing in villages ;
          11 differences in diet ;
          12 AVP ; e.g. lack of physical activity ;
2 (b) (i) 1 nasal hairs, trap particles / AW ;
               2 goblet cells secrete mucus ;
               3 particles trapped in the mucus ;
               4 cilia moving the mucus ;
               5 mucus (containing particles) moved, away from the gas exchange surface
                  / towards the throat / AW ;
               6 mucus, swallowed / AW ;
               7 AVP ; phagocytes / sneezing
2 (b) (ii) more oxygen ;
                less carbon dioxide ;
                less water vapour ;
2 (c) (i) intercostal ; 1
2 (c) (ii) (pressure) decreases and (volume) increases ;

Question

(a) A small population of rabbits was introduced to an island where rabbits had never lived
            before.
            Fig. 7.1 shows the change in the size of the rabbit population over a few years.

               

                 Complete Fig. 7.1 by labelling the four phases of this population growth.
                  • death                                  (use letter D)
                  • exponential (log)             (use letter E)
                  • lag                                       (use letter L)
                  • stationary                          (use letter S)
                                               Write the letters D, E, L and S on Fig. 7.1 in the spaces provided.            [3]
      (b) State three factors that could affect the rate of growth of this rabbit population.

           

Answer/Explanation

Ans:

 

Question

(a) Table 4.1 shows some of the top ten causes of death in parts of the world during 2010.

             

               (i) Draw the bars for the adult females on Fig. 4.1.                                                                                                                [1]
              (ii) Calculate the percentage of males dying from causes other than those in
                       Table 4.1.
                       Show your working.

                                                                                                                                                                   

              (iii) State the type of cancer, listed in Table 4.1, that occurs only in males.

                     

    (b) The lifestyles of people can affect their risk of dying from some diseases.
          (i) Suggest three actions that humans could take to lower their risk of dying from
                 coronary heart disease.

             

       (ii) In 2010 2% of adult male deaths were due to liver disease.
               Suggest one aspect of their life style that could have caused this.

             

Answer/Explanation

Ans:

 

Question

Some animals were introduced into a new habitat.

Fig. 10.1 shows how the number of animals in the population changed with time.

(a)   Name phase A and phase B of the population growth curve shown in Fig. 10.1.

(b)   Fig. 10.2 shows the human population growth curve since the year 1 A.D.

(i)     State and explain how the human population growth curve is different to the growth curve in Fig. 10.1.

(ii)   Suggest one social implication that might arise from the current size of the human population.

Answer/Explanation

Ans:

A  : log / exponential (phase) ;

B  : stationary (phase) ;

(b)    (i)       difference:

no stationary phase or exponential / log, phase has

continued / AW ;

explanation:

development of farming / improved food supplies / AW ;

ref. to sanitation / hygiene / AW ;

ref. to medical treatments / care ;

use of technology / AW ;

AVP ;

(ii)     lack of (named) resource leading to:

• idea of conflict / war / social unrest / riots

• starvation food shortages /

• people encouraged to have small families /

• spread of disease or overcrowding /

• unequal distribution of resources /

• poverty /

• migration /

• AVP;

Question

Fig. 8.1 shows a woodland food web.

(a) (i) Name one organism in this food web which can trap light energy to produce sugars.
           ……………………………………………………………………………………………………………………..

       (ii) Complete this food chain from the food web shown in Fig. 8.1. Write the name of one organism in each box.

(b) (i) Define the term population.
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(ii) Define the term trophic level, using an example from Fig. 8.1.
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(c) Some of the leaves and fruit from the oak tree are not eaten by organisms shown in the food web. The leaves and fruit fall to the ground where they are slowly broken down.

(i) Name one kind of organism responsible for this break down.
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(ii) Explain how this break down is helpful to the oak trees.
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Answer/Explanation

Ans:

(a) (i) (oak) tree/primrose;

     (ii) (oak) tree flies; (spiders) blue tits owl;

(b) (i) group of organisms of the same species;
            living in the same area (at the same time);

      (ii) position of an organism in a food chain/food web;
            example from food web in Fig. 8.1;

(c) (i) decomposer/ bacteria/ fungi;

      (ii) releases minerals from leaves;
            minerals absorbed (into plant) from soil;
            releases carbon dioxide;
            carbon dioxide absorbed by leaves for photosynthesis;
            AVP;

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