GR 11 LIFE SCIENCES

Assignment: Population Ecology & Human Impact on the Environment

August 2020

Name : __________________________________ marks : /80

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SECTION A

QUESTION 1

1.1 Read the passage below and answer the questions that follow.

1.1.1 Distinguish between the terms “prey” and “predator”.

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1.1.2 Refer to the passage and give the names of the organisms involved in each of the following:

a) intraspecific competition

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b) interspecific competition

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1.1.3 Explain why the impala population continued to decline after 80% died during the winter.

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1.4 Explain what is meant by each of the following in a population.

a) Carrying capacity

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b) Species

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1.1.5 Is predation a density-dependent factor or a density-independent factor? Give a reason for your answer.

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1.2 The table below shows the consumption of food by an elephant. Answer the questions that follow.

1.2.1 Use the formula C = P + R + (F + U) and calculate the amount of energy that is present in the waste products excreted by the elephant. ___________________________________________________________________ ____________________________________________________________________(4)

1.3 Study the representation of the life cycle of the parasitic flatworm, Schistosoma, and answer the questions that follow.

1.3.1 Name and explain what type of parasite Schistosoma is.

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1.3.2 Name the letters A to E.

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(7)

TOTAL QUESTION 1:25

QUESTION 2

2.1 Read the article below and study the graph.

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2.1.1 Use the information in the line graph to determine the relationship between the seasons and nitrate levels in the river from 2010 to 2012.

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2.1.2 State why the authorities of Des Moines could not be fined for the violation of the legal limit of nitrate levels in drinking water.

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2.1.3 Motivate why the drinking water of the city can still be considered unhealthy. ________________________________________________________________________

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2.1.4 Name the type of water pollution caused by run-off water that has an excess amount of nitrate.

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2.1.5 Describe the effect of the pollution mentioned in QUESTION 2.1.4 on aquatic life.

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(9)

2.2 A group of Grade 12 learners had the effect of water temperature on the solubility of oxygen tested. They took water samples from a river, which runs along numerous industries which uses water from the river for cooling.

The results are shown in the table below:

2.2.1 Formulate a hypothesis for this investigation.

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2.2.2 Describe the effect on the organisms that live in the water, if water with a higher temperature is pumped back into the river.

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2.2.3 Name each of the following for this experiment:

(a) Independent variable

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(b) Dependent variable

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2.2.4 Name TWO ways in which the learners can assess the reliability of their result increase.

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2.5 Draw a line graph to indicate the effect of elevated water temperature, from 0 °C to 60 ° C, on the solubility of oxygen.

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(14)

TOTAL QUESTION 2: 23

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QUESTION 3

3.1 Read the article below and answer the questions that follow.

3.1.1 Explain what is meant by “food insecurity” and use ONE word from the article to indicate that there is food insecurity in sub-Saharan Africa.

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3.1.2 Name TWO ways in which food security in Africa can be improved according to this extract.

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3.1.3 In addition to the ways mentioned in QUESTION 3.1.2, discuss TWO other poor farming methods that could cause crop production in Africa to decline.

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3.1.4 Give ONE reason, according to the article, why there is reduced availability of of water on farms in Africa.

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3.1.5 Explain how the use of fertilizer can lead to reduced water quality.

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(14)

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3.2 Study the passage below and answer the questions that follow.

3.2.1 Give the meaning of:

(a) Biodiversity

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(b) Foreign plants

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3.2.2 Give TWO factors, other than invasive plants, that can reduce biodiversity.

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3.2.3 Explain how biological control is applied to control invasive plants.

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3.2.4 List TWO criteria, based on the extract, that can be used to control alien plants.

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(10)

TOTAL QUESTION 3: 25

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QUESTION 4

4.1 Study the diagram below that shows the structure of a landfill site and answer the questions that follow.

4.1.1 Name the flammable gas that escapes through the chimney.

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4.1.2 Name ONE possible use of the gas in QUESTION 4.1.1

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4.1.3 Give ONE reason why the waste at landfill sites are regularly covered with sand during intervals.

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4.1.4 Give ONE visible reason why this landfill site will not be longer used.

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4.1.5 Name TWO ways by which the:

(a) landfill site can be used after rehabilitation.

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(b) amount of waste taken to the landfill site, can be reduced.

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(8)

TOTAL QUESTION 4: 8

GRAND TOTAL: 80

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