SPM Biology 2019

Question

9. (a) Diagram 9.1 shows two quadrat samplings, P and Q. This study has been carried out to estimate the distribution of Pleurococcus sp. population on a tree trunk and a rock.

Rajah 9.1 menunjukkan dua persampelan kuadrat, P dan Q. Kajian ini dijalankan untuk menganggarkan taburan populasi Pleurococcus sp. pada batang pokok dan batu.

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Determin the population distribution of Pleurococcus sp. in Quadrat P and Quadrat Q. Explain the factors that affect the population distribution of Pleurococcus sp. in Quadrat P or Quadrat Q.

Tentukan taburan populaso Pleurococcus sp. dalam Kuadrat P dan Kuadrat Q. Terangkan faktor-faktor yang mempengaruhi taburan populasi Pleurococcus sp. dalam Kuadrat P atau Kuadrat Q.

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(b) Diagram 9.2 shows two modern technologies that help sustain a balanced ecosystem.

Rajah 9.2 menunjukkan dua teknologu moden yang membantu mengekalkan keseimbangan ekosistem.

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Discuss how these modern technologies in Diagram 9.2 perform in helping to sustain a balanced ecosystem.

Bincangkan bagaimana teknologi moden dalam Rajah 9.2 berperanan dalam membantu mengekalkan keseimbangan ekosistem.

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Answer ( 1 )

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    2020-12-18T09:26:06+08:00

    9. a)

    Population distribution: 

    using percentage frequency,

    Quadrat P:

    41%

     

    Quadrat Q:

    15%

     

    Take into account only quadrats which are half and more filled. Divided by the total number of quadrats. Then multiply by a 100%

     

    Factors: 

    Temperature

    Light intensity

    Humidity 

    There are actually other factors like pH, however pH is not really relevant for this question as they have not provided the pH ranges for the quadrats.

     

    One factor that can affect population distribution is temperature, Pleurococcus sp. cannot survive in extreme high temperatures. They prefer milder temperatures. Therefore, there is a higher population distribution in Quadrat P as shade is provided by the tree compared to Quadrat Q where the sun is directly shining on the surface on the rock creating a hotter temperature. 

     

    Furthermore, light intensity also affects the population distribution. A moderate light intensity is preferred as seen with the higher population density in Quadrat P where the light intensity is lower than direct exposure of sunlight on Quadrat Q. 

     

    This is because high temperatures and light intensities tend to dehydrate the cells of the organism.

    At Quadrat P the moderate degree of light intensity and temperature is able to maximize the rate of photosynthesis.

     

    Moreover, higher humidity can also result in a higher population density. At Quadrat P, it is most likely more humid, there’s more water vapour and moisture compared to Quadrat Q. 

    Since in Section B you actually get to choose which questions to answer (pick two), I would actually recommend answering question types like the one below about the environment. There’s a lot of points you can think up of for these type of questions.

    b) These modern technologies are environment friendly. Solar energy is a renewable source of energy which means it will not be depleted and there’s a continuous supply of it. Solar energy doesn’t pollute the environment and it can be harnessed via the use of solar panels. The harnessed solar energy can be converted to electrical energy which can then be used to power the house in terms of electricity and heating. 

     

    The combustion of fossil fuels like coal can lead to an increase in the production of carbon dioxide (CO2). CO2 is a greenhouse gas which can contribute to the greenhouse effect, more heat gets trapped within the atmosphere which increases the temperature on Earth resulting in global warming.

     

    Furthermore the combustion of coal may lead to air pollution. Sulphur dioxide and oxides of nitrogen may be produced from the combustion of coal. When they combine with water vapour it may lead to the formation of sulphuric and nitric acid causing acid rain. Acid rain can cause buildings to corrode and kills phytoplankton as pH in aquatic waters get more acidic, this could then lead to a disruption in the food chain. 

     

    Thus, the use of electric trains which replaces charcoal can help to sustain a balanced ecosystem as there is a reduction in the amount of CO2 produced, reducing global warming. Air pollution and acid rain formation can be prevented as well.

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