7 . G11 LifeSciences DigitalSupport web Environmental Studies Worksheets

Study & Master Support Pack | Grade 11 CAPS Life Sciences Environmental studies This support pack for the Environmental studies strand in the Life Sciences Grade 11 CAPS curriculum provides practice exercises. All exercises have the answers provided. Learners can work through these individually at home or these could form the basis of a catch-up class or online lesson. You have permission to print or photocopy this document or distribute it electronically via email or WhatsApp. Cambridge University Press Africa is a proudly South African publisher. For more information on our Study & Master CAPS-approved textbooks and valuable resource materials, visit www.cambridge.org Brighter thinking | Better learning www.cambridge.org

WORKSHEET 9: Population ecology 1. A group of students sampled an area of 10 m × 10 m, marked off on the school’s rugby field. Their aim was to determine the population size of dandelion weeds growing amongst the lawn grass. To do this, they made use of five quadrats, each measuring 1 m by 1 m, as shown in the diagram below. Quadrats in randomly chosen sites (each quadrat encloses one square metre) dandelion plant grass 1.1 Name the method that was used to determine the population size of dandelions on this section of the rugby field. 1.2 Calculate the area of the rugby field that was marked off for this investigation. 1.3 Estimate the total number of dandelions that occur in this marked- off area of 10 m × 10 m. Show all your calculations. 1.4 Mention an important precaution that should be taken in consideration when using this method to determine the size of a population. Give a reason for this precaution. 1.5 How can you improve on this method in order to obtain a more reliable assessment of the population size?

2. Study the population growth pattern shown in the graph below and then answer the questions that follow. E F Number of individuals – population size A B C D Time 2.1 What does the dotted line at E represent? 2.2 What do the arrows represent? 2.3 Why are some of the arrows longer than others? 2.4 With reference to the letters A, B, C and D, briefly describe the growth pattern of each one of these stages in the population growth pattern. 2.5 If this graph represents a sheep farm in the Karoo, what will happen to E if the farmer introduces another 200 sheep during stage D? 2.6 Name the type of growth pattern shown in this graph. 3. Your class is given the task of assessing the population density of a certain species of locust in a municipal park close to your school. A specific area has been marked off and you are expected to carry out the investigation within this area. You are provided with the following equipment and a formula: • A butterfly net • A marker with non-toxic paint • A clip board and note paper • The formula: N = M × C           R Where: N = the population size M = the number of locusts caught and marked during the first catch C = the total number of locusts caught during the second catch R = the number of marked locusts found in the second catch 3.1 Name the method that you will use to determine an estimate of the locust population. 3.2 Write up a step-by-step plan that you will use to assess the population density of locusts in the park. Also include the nature of calculations that will be required. 3.3 Mention and explain at least three precautions that should be considered to ensure that you obtain the most accurate assessment of the population size.

3.4 During the above practical investigation, the following data were recorded: Number of locusts caught and marked during the first catch = 15 (M) Total number of locusts caught during the second catch = 30 (C) Number of marked locusts found in the second catch = 9 (R) Calculate the estimated population size of the locusts. 3.5 Suggest the most appropriate method for assessing the size of a population in each of the following examples. i The population of humans in Gauteng. ii The population of white rhinos as shown on a series of aerial photographs taken over the Hluhluwe-Umfolozi game reserve complex. iii The population of African potato plants in a nature reserve. iv The population of ladybirds (flying insects) in a nursery that cultivates and sells rose plants. 4. Study the illustrations below and then answer the questions that follow. impala X Population size of predator and prey Y leopard Time A B C 4.1 What type of interaction is indicated at A? 4.2 Explain the interaction mentioned in Question 4.1. 4.3 What effect will this interaction have on the size of the impala population? 4.4 With reference to graph B, which of X or Y indicates: i The impala population? ii The leopard population? 4.5 Explain the pattern of the two growth curves in graph B. Make reference to X and Y as well as leopards and impala. 4.6 What type of interaction can be expected among the population shown at C, if their food sources suddenly decrease? 4.7 Define the interaction mentioned in Question 4.6.

5. The age-gender pyramids below represent the population distribution of two different countries, A and B. Age group in years Age group in years A 85+ B 85+ 80–84 80–84 75–79 75–79 70–74 70–74 65–69 65–69 60–64 60–64 55–59 55–59 50–54 50–54 45–49 45–49 40–44 40–44 35–39 35–39 30–34 30–34 25–29 25–29 20–24 20–24 15–19 15–19 10–14 10–14 5–9 5–9 0–4 0–4 4 2 0 0 2 4 8 6 4 2 0 0 2 4 6 8 Percentage Percentage Percentage Percentage of females of males of females of males 5.1 In pyramid A, which gender has the higher proportion living beyond the age of 65? 5.2 In pyramid B, which age group makes up exactly 4% of the male population? 5.3 Which pyramid represents the population of a developing country? 5.4 Give two reasons for your answer to Question 5.3.

MEMORANDUM FOR WORKSHEET 9 1.1 Quadrat method/sampling method 1.2 Area = length × breadth, thus area = 10 m × 10 m = 100 m2 1.3 Average number of dandelions per quadrat 9 + 7 + 1 + 3 + 10 total dandelions       5 quadrats = 6 average per quadrat Thus the estimated number of dandelions in the area marked off: = average number per quadrat × total area of sampling site = 6 × 100 = 600 dandelions per 100 m2 1.4 Position the 5 quadrats at random, e.g. wear a blindfold before throwing each one of the five quadrats in random directions on the area to be investigated. 1.5 Repeat the entire procedure a few times and calculate the average. 2.1 Carrying capacity 2.2 Environmental resistance 2.3 The thickness depicts the intensity of environmental resistance, i.e. the thicker the arrow, the greater the pressure to limit population growth. 2.4 A – Lag phase: The rate of growth is very slow because the population number is small. The population is probably newly introduced into the habitat and it takes time to settle down and acclimatise before they can reproduce. There is also a time lag before mature individuals can find mates and reproduce. B – Accelerating phase (also called the log or exponential phase): The population increases exponentially due to the abundance of resources and space available. Environmental resistance is low or absent. Birth rate exceeds the death rate. C – Decelerating phase: Growth rate slows down as the environmental resistance increases. Competition for resources increases. Birth rate is still higher than the death rate. D – Equilibrium phase (also called the stationary phase): The carrying capacity is reached and the birth rate and death rate go up and down, i.e. the population number fluctuates around a set carrying capacity. If environmental conditions remain the same, then the population will remain stable at this level. 2.5 This will lower the carrying capacity, because of habitat degradation due to overgrazing. The farm will no longer be able to support the same number of sheep. If the sheep are removed and the veld is left fallow for a long period, the grazing potential may be restored again. 2.6 Logistic growth (also called a sigmoid or S-curve).

3.1 Mark-recapture method 3.2 Step 1: Use the butterfly net to catch a number of locusts. Carefully mark each locust on the upper thorax. Record the number that you have marked. Step 2: Set the marked locusts free and allow at least two hours for the marked locusts to mingle with the rest of the population. Step 3: Catch another round of locusts. Ensure that this total is larger than the number in the first catch. Record this total and count the number of recaptured locusts (i.e. the marked individuals) and also record this. Set all these locusts free. Step 4: Calculate the population size by using the formula: N=M×C R In this formula: N = the population size estimate M = the number of locusts marked in the first catch C = total number of locusts caught in the second catch R = the number of marked locusts in the second catch 3.3 The catch and marking procedure should be as gentle and harmless as possible so that it does not jeopardise the chances of catching the insect again; enough time should be allowed between the two catches for the population to mix but not so long that it allows immigration and emigration; ensure that the second catch is larger than the first catch to arrive at a more reliable result; the method should not affect the free movement or behaviour of the insect. 3.4 N = M × C = 15 × 30 = 50 locusts    R 9 3.5 i Census (direct counting) ii Counting (on photographs) iii Quadrat (sampling) method iv Mark-recapture method 4.1 Predation 4.2 Predators (leopard) hunt and kill their prey (impala). 4.3 It will regulate the population size of impala so that it remains within the carrying capacity. 4.4 i X ii Y 4.5 The initial increase in the impala population as prey, shown in X, increased the number of prey available to the predators, i.e. the leopards (Y). So both curves show an upward trend. This is followed by a downward trend as soon as over-predation occurs, leading to a drop in population numbers for both predator and prey species. Once the population numbers have dropped to well below the carrying capacity of each, both populations will increase in number again. These two patterns of growth are synchronised (occur in harmony with each other). They will continue to repeat and fluctuate in a stable equilibrium unless other environmental conditions, such as a drought or emigration, disrupt the equilibrium. 4.6 Intraspecific competition 4.7 An interaction between members of the same species competing for the same limited resources.

5.1 Female 5.2 The age group of 25–29. 5.3 Pyramid B 5.4 The country maintains a high natality (birth) rate, and the life expectancy is low – fewer old people.

WORKSHEET 10: Human impact on the environment 1. Without the natural greenhouse effect, Earth’s average temperature will be approximately –18 °C. Explain how the natural greenhouse effect functions to protect us from such freezing temperatures. 2. Conservation scientists have come up with the phrase “carbon footprint”. 2.1 Explain what is meant by a carbon footprint. 2.2 Compare the carbon footprints in each of the following two examples: i A person who eats meat every day compared to a vegan (a person who follows a diet without any animal products). ii A motor car racing champion at Kyalami compared with a high school athlete in a rural area. Both practise their sport for eight hours every week. 2.3 Study the table below that represents the amount of carbon dioxide emissions from different countries in 2002. Countries Total annual CO2 emission in Proportion of world 2002 (million tonnes per year) total (%) USA 5 673 22 China 3 733 15 Russian Federation 1 477 6 India 1 106 5 South Africa 364 2 Other countries X 50 Total 24 706 100 i Which one of the named countries has the largest footprint? ii Calculate the total annual CO2 emission in the other countries (X) from the table. 2.4 The Kyoto Protocol was drafted by the United Nations (UN) in 1997 to provide a global action to reduce CO2 emissions by the year 2012. The United States of America (USA) did not agree to implement the Kyoto Protocol. i Explain the impact that this decision by the USA has on the rest of the world. ii If you were working for the United Nations, put forward an argument that you would use to persuade the USA to implement the Kyoto Protocol. iii South Africa has the highest annual emission of CO2 in Africa. Give three reasons for this. iv Draw a pie chart to show the proportion of CO2 emissions from all the countries shown on the table. Show your calculations.

3. A group of learners were concerned about the inflow of sewage into a river close to the school. They asked the question: “Does the sewage deplete the amount of oxygen in the river?” They decided to conduct a formal investigation by stating a hypothesis and then planning the procedure for the investigation. The learners collected water samples at different places (X, Y and Z) along this river. They used an oxygen meter to measure the level of dissolved oxygen and determined the solid mass of samples of sewage. They also collected aquatic animals at each of these three sample sites. The graph below shows the change in the amount of substances (oxygen and waste) in the water along the course of the river. The point at which sewage enters the river is indicated on the graph. Changes in the amount of oxygen and waste in a river entry of sewage oxygen Amount of substances waste X Y Z Direction of river flow They used the presence or absence of the following animal species as indicators of the degree of water pollution in a river, as shown in the table below. Organisms present Degree of water pollution Mayfly nymph Unpolluted and sufficient oxygen in the water Leeches Moderately polluted with reduced levels of oxygen in the water Sludge worms Severely polluted and the water has very little dissolved oxygen 3.1 Which organism listed in the table above would most probably have been present at: i X ii Y iii Z? 3.2 Name two factors that should be kept constant while collecting water samples. 3.3 Explain one precaution that the learners should take to ensure their own safety while collecting the samples. 3.4 Use the data in the graph to describe the relationship between the amount of oxygen and the amount of waste from the point at which the sewage enters the river. 3.5 i Give an example of a hypothesis that the learners may have stated at the start of the investigation. ii State the conclusion to the hypothesis that you formulated in Question 3.5 i.

4. The graph below shows the relationship between human population growth and the number of species that have become extinct over the past 200 years. Species extinction and human population 60 000 8 000 7 000 50 000 extinctions Extinction numbers Population (millions) 6 000 40 000 human population (millions) 5 000 30 000 4 000 3 000 20 000 2 000 10 000 1 000 0 0 1800 1830 1860 1890 1920 1950 1980 2010 Time 4.1 Name the dependent variable(s) illustrated in this graph. 4.2 Name the independent variable(s) illustrated in this graph. 4.3 Describe the relationship between human population growth and the number of species that have become extinct, as shown in this graph. 4.4 The current phase of species extinction is often called the sixth mass extinction. It has been established that this mass extinction is occurring at a much faster rate than the previous five mass extinctions. This is mainly due to human impact on the environment. For each of the following forms of human activities, explain how they contribute to extinction and the loss of biodiversity: i Monoculture as a farming strategy ii Overgrazing of livestock iii Mining iv Urbanisation 4.5 Suggest two strategies that can be used to restore biodiversity in each of the following: i On farms ii In cities

5. Answer the following questions on solid waste. 5.1 Solid waste is usually disposed of by being buried in a municipal landfill site. i State two ways in which landfill sites affect the environment. ii Suggest three ways in which the impacts mentioned in Question 5.1 i can be reduced. 5.2 The following table shows the total amount of solid waste and the recyclable content within this waste that was dumped in a landfill site near a South African city over a period of eight years. Year Total amount of waste Recyclable content (millions of (millions of tonnes) tonnes) 2006 1,49 0,78 2007 1,59 0,82 2008 1,80 1,20 2009 1,93 1,10 2010 1,95 0,91 2011 1,97 0,85 2012 1,99 0,73 2013 1,79 0,45 What percentage of recyclable material in the waste was dumped? i In 2006 ii In 2013? iii Describe the trend in the total amount of waste produced from 2006 to 2013. iv Describe the trend in the amount of recyclable materials that was dumped from 2006 to 2013. 5.3 A recycling facility was introduced during this period. i In which year was the recycling facility introduced in this city? ii Give a reason for your answer in Question 5.3 i above. 5.4 In 2013, the local municipality ran awareness and educational programmes to encourage more people to recycle their glass, paper, plastic, aluminium, other metals and organic waste. The slogan of this campaign was “reduce, reuse, recycle”. i Explain what is meant by each one of the terms reduce, reuse and recycle. ii How does recycling benefit the environment? iii Was this awareness campaign successful? Explain your answer.

MEMORANDUM FOR WORKSHEET 10 1. Solar radiation from the Sun is very hot, so it travels extremely fast through the atmosphere in the form of short wavelengths. Some of this is reflected back into the atmosphere but because the reflected rays are now cooler, it travels much slower in the form of longer wavelengths. Greenhouse gases are able to absorb these long waves and retain them in the form of heat, rather like a blanket in the Earth’s atmosphere. It is this retention of heat that prevents the Earth from freezing and enables the atmosphere to maintain a temperature that can support life on Earth. 2.1 A carbon footprint is a way of measuring the amount of CO2 that is released by a person’s activities and lifestyle. 2.2 i The vegan’s footprint is considerably smaller because it requires less fossil fuel input to harvest grain, fruit and vegetables. ii The high school athlete will have a considerably smaller footprint than the racing car driver who uses a great deal of fossil fuel (petrol and oil) to practise his sport. 2.3 i The United States of America ii  50 × 24 706 100 = 12 353 million tonnes of CO2 per year 2.4 i The USA is the largest CO2 emitter in the world and therefore contributes more to global warming than any other country. This has a negative effect on the welfare of other countries because it influences climates negatively in the rest of the world. It also sets a bad example to other countries. ii Excess CO2 in the atmosphere raises global temperatures, so the action of the USA by not reducing their carbon emissions will affect all countries including the USA. It is thus recommended that they observe the Kyoto Protocol aims. iii South Africa has more industries that emit CO2; more cars on the road; and more large cities that all emit CO2 compared to the other countries in Africa. We also have more coal-based power stations and, in many rural areas, wood burning contributes to the carbon load in the atmosphere. iv USA other countries China Russia India SA

3.1 i Mayfly nymphs ii Sludge worms iii Leeches 3.2 The volume of the samples collected should remain the same; samples must be taken at the same time in all the areas; water must be disturbed as little as possible; clean equipment must be used. 3.3 Wear rubber gloves and protective clothing to prevent any contamination with germs in the water. It is preferable to attach a bottle to a rod and string that can be dragged through the water, to prevent germ contamination. 3.4 As the amount of waste increases, the amount of oxygen decreases. When the concentration of waste levels off, the amount of oxygen increases until it levels off to the same level as before the waste was added. 3.5 i Sewage in the river depletes oxygen levels in the water. ii Conclusion: The hypothesis is accepted. 4.1 Extinction number and human population numbers. 4.2 Time 4.3 As the human population increased in number, the number of species that became extinct also increased, almost at the same rate. Both show an accelerated increase between 1920 and 1980. 4.4 i Monoculture destroys large areas of natural habitats, replacing it with only one kind of crop. It also replaces the natural variety of food webs with a few species of pest insects that are attracted by the crops. It requires large quantities of pesticides and herbicides that are harmful to indigenous animal and plant species on the farm as well as the surrounding area. ii Overgrazing of livestock depletes the vegetation to a point where it is no longer able to grow back at the same rate as it is being grazed. This accelerates soil erosion and the soil can no longer sustain the former habitat and biodiversity. iii Mining transforms natural habitats into wastelands. Natural biodiversity is replaced with rock rubble (in open cast mines), waste dumps and the chemical pollution from deep shaft mines. They cause air pollution, changes in the soil and water pH and dust pollution, which kills off plants and animals. iv Urbanisation replaces natural habitats with vast expanses of concrete and tarred roads. Wildlife is kept out by fences, electrical power lines kill off raptors and bright spotlights kill insects. The popular use of exotic plants in gardens also adds to the loss of natural biodiversity in cities. 4.5 Any two of: i On farms: replace monoculture by integrating crops with strips and sizable patches of indigenous vegetation; restore natural habitats such as wetlands and forests. ii In cities: plant indigenous vegetation in gardens, instead of exotics; create small gaps at the bottom of fences for animals such as frogs to migrate.

5.1 i Any two of: chemicals that leak from dump sites may pollute underground water stores; they are breeding grounds for germs and attract flies and rats that can cause diseases; they release methane that can cause fires and contribute to greenhouse gases. ii Any three of: line the landfill with impermeable material to prevent leakages; keep the public away from dump sites and cover layers with soil; convert the methane into electricity or pipe it to homesteads as a source of gas for cooking. 5.2 i 0,78 ÷ 1,49 × 100 = 52% ii 0,45 ÷ 1,78 × 100 = 25% iii The total waste increased from 2006 until 2012 when it started to decrease in 2013. iv There was an initial increase of recyclable waste from 2006 until 2008, but then it started to decrease from 2008 to 2013. 5.3 i In 2008. ii That is when the amount of recyclable material started to decrease. 5.4 i Reduce: Cut back on purchases and buy only what is really needed. Reuse: Find another use for unwanted items such as glass bottles for storage. Recycle: Take recyclable goods to recycling depots so that they may be used as a resource for making new items. ii It reduces the amount of raw materials, water and electricity required to make new items. This saves natural resources. Less processing is required in factories so it releases less pollutants into the environment and less CO2 that speeds up global warming. iii Yes. The recyclable waste decreased rapidly from 2012 to 2013.