Questions
Q1.
Many scientists think there is a link between global warming and increased levels of carbon dioxide and methane in the upper atmosphere. Most organisms are found in regions where the temperature range is between 0 ºC and 40 ºC at the Earth's surface.
(a) (i) Suggest why temperatures below 0 ºC or above 40 ºC would be unsuitable for most organisms. (2) ... ... ... ... ... ...
(ii) Explain how this range of temperatures has been maintained by the presence of carbon dioxide and methane in the upper atmosphere.
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(iii) Place a tick in the box in each row to indicate whether each technique could provide evidence of climate change having occurred in the past.
*(b) It has been suggested that a reduction in the use of fossil fuels is necessary if further global warming is to be prevented. Some scientists disagree with this suggestion.
Suggest why these scientists do not agree that a reduction in the use of fossil fuels will prevent further global warming.
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Q2.
The mean global temperature is expected to increase as a result of climate change. The graph below shows the predicted changes in mean temperature in New Zealand, during the 21st century. A higher and lower estimate of these changes have been made.
(a) (i) Explain how increases in carbon dioxide and methane, released into the atmosphere, may be contributing towards the estimated changes in mean temperature shown in the graph.
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(ii) Suggest why a higher estimate and a lower estimate were made.
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(b) Tuataras are reptiles found only on a group of small islands off the coast of mainland New Zealand. Adult tuataras grow to approximately 65 cm in length. They feed on small mammals, bird chicks and invertebrates such as insects and worms.
Tuataras build nests in which their eggs are laid. The gender (sex) of the tuatara, that hatches from an egg, is determined by the incubation temperature in the nest. A temperature of 22 ºC or above will mean that a male tuatara will hatch. Female tuataras only hatch from eggs incubated below 22 ºC.
During the breeding season in 2000, the temperature of the nests ranged between 18 ºC and 24 ºC.
(i) Suggest how the changes in the mean temperature, shown in the graph on page 6, might affect the tuataras on the islands off the coast of New Zealand.
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(ii) Suggest how other animal populations on these islands might be affected by changes in the tuatara population. (2) ... ... ... ... ... ...
(Total for question = 10 marks)
Q3.
If a tree trunk is cut across horizontally, growth rings can be seen in the cut surface. The most significant factor that affects the formation of growth rings is environmental temperature. In regions where there is an annual cycle of seasonal temperature changes, it is possible to estimate the year in which a particular ring was formed.
In Nepal, there is an annual seasonal cycle of three distinct periods that is shown in the table below.
Data from growth ring studies and other sources have been used to estimate the changes in environmental temperature in Nepal during the past 400 years.
(a) Place a cross in the box next to the term used to describe the scientific study of tree growth rings.
(1)
A climatology
B dendrochronology
C ecology
D ethnobiology
(b) Compare the changes in mean environmental temperature between the pre-monsoon and the post-monsoon periods from 1600 to 2000.
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(c) (i) Suggest how scientists could use these data to predict future climate change.
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(ii) Suggest why some scientists may not be convinced that these data can be used to predict future climate change.
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(Total for question = 11 marks)
Q4.
Frogs are ectothermic animals. This means that their body temperature will vary as the environmental temperature varies.
(a) Explain why body temperature affects the rate of development of animals.
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(b) Several species of the frog genus, Rana, can be found in North America. Many of these species inhabit areas within a range of latitudes from the colder north to the warmer south.
The table below shows data for four of these species, R. clamitans, R. palustris, R. pipiens and R.
sylvatica.
latitudes inhabited by each species of frog. (2) ... ... ... ... ... ...
(c) Complete the species names in the diagram below to show the most likely distribution of
Rana from north to south.
(2)
(d) Populations of the different species overlap on the boundaries of each latitude range.
Suggest why interbreeding does not take place between these populations.
(e) Suggest how global warming may affect the distribution of these species of Rana in North America. (3) ... ... ... ... ... ... ... ... ...
(Total for question = 13 marks)
Q5.
Filamentous algae are simple photosynthetic organisms that consist of long strands of very similar eukaryotic cells. Each of the cells in the strand is enclosed within a cellulose cell wall. The strand increases in length as the cells divide and elongate.
The photographs below show some cells in strands of a filamentous alga, as seen using a light microscope.
(a) (i) Put a cross in the box next to the term that describes the process involved in the cell divisions in a filamentous alga.
(1)
A exocytosis
C mitosis
D osmosis
(ii) Put a cross in the box next to the structure that would not be found in a cell from the strand of a filamentous alga.
(1)
A lysosome
B mitochondrion
C plasmid
D ribosome
(b) An investigation was carried out into the effect of temperature on the rate of growth of a filamentous alga. Several short strands of the alga were placed into culture solutions which were kept at five different temperatures and at a high light intensity.
The number of cells in the strands, in each culture solution, was counted at the beginning of the time period and again after 18 days. The rate of growth was then calculated.
The results of this investigation are shown in the graph below.
(i) Name the independent variable in this investigation.
(1)
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(iii) Suggest why it was important that this investigation was carried out at a high light intensity.
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(iv) Suggest two abiotic factors, other than light intensity, that would need to be controlled in this investigation. (2) 1 ... 2 ...
Q6.
Plant growth involves mitosis, cell division and cell differentiation and is influenced by environmental factors such as temperature.
(a) The diagram below shows the stages in the growth of a root in a plant seedling.
(i) Place a cross in the box next to the correct sequence of stages in mitosis.
(1)
A Metaphase, anaphase, prophase, telophase
B Prophase, anaphase, metaphase, telophase
C Prophase, metaphase, anaphase, telophase
D Telophase, metaphase, anaphase, prophase
ii) Place a cross in the box next to the material that would be synthesised to form the cell wall of the seedlings.
(1)
A Cellulose
B Cholesterol
C Glycogen
D Thrombin
(iii) Place a cross in the box next to the tissue that would form the vessels in a root, following differentiation.
(1)
A Chorion
B Endothelium
C Sclerenchyma
D Xylem
(b) A student carried out an investigation into the effect of temperature on the growth of plant seedlings. The two species that she chose for the study were sea plantain, Plantago maritima
Sets of seeds from each of these species of plant were germinated at 18 ºC. As soon as they germinated, the seedlings were placed in three temperature-controlled rooms at 10 ºC, 14 ºC and 18 ºC. They were allowed to grow for 50 days. Samples of seedlings were taken at 5-day intervals and their mean dry masses were recorded.
The results of this investigation are shown in the tables below.
(i) Suggest how these results could be displayed in order to compare the effect of temperature on the growth of seedlings of these two species.
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(ii) Suggest why all of the seeds were germinated at 18 ºC before being placed in the temperature-controlled rooms. (2) ... ... ... ... ... ...
(iii) Use the data in the tables to suggest which of the two species is better adapted for growth at a wide range of latitudes (distance from the equator). Give reasons for your choice.
(Total for question = 12 marks)
Q7.
(i) Describe and explain how global warming could affect plant species.
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(ii) Explain how the effects on plant species could affect animal species.
The soils in wet, marshy lands usually have anaerobic conditions that inhibit decomposition. As a result of this, dense layers of semi-decayed organic matter, known as marshland peat, build up.
The table below shows some of the components of marshland peat.
(a) Describe the chemical nature of cellulose.
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(b) Name a plant tissue that could be the main source of the lignin found in marshland peat.
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(c) All of the components shown in the table are organic carbon compounds. Describe the role of microorganisms in the recycling of the carbon from these compounds.
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(d) Landscapes rich in peat act as carbon sinks. However, during recent decades, some countries have been draining and clearing marshy peatlands to grow crops, such as palms, to produce biofuels. During this clearance and drainage, the rate of decomposition in the peat increases and the organic debris is burnt. This change of use of the peatlands has turned carbon sinks into carbon sources.
(i) Suggest one reason why some countries may decide to drain their marshy peatlands for the production of biofuels.
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*(ii) Biofuels are considered to be carbon neutral.
Suggest why the continued draining and clearance of peatlands may contribute towards global warming even though they may be used to produce biofuels.
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(Total for question = 13 marks)
Q9. Global warming is a worldwide problem that affects climate and the environment.
(a) The graph below shows the number of forest fires in five regions of Brazil, for 2003 to 2007.
(i) Place a cross in the box next to the best conclusion that can be drawn from these results about the number of forest fires in Brazil.
(1)
A The number of forest fires has generally decreased
B The number of forest fires has generally increased
C The number of forest fires in Mato Grosso each year is always higher than in other areas
D There are no clear trends
*(ii) Explain how forest fires may lead to global warming.
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(b) (i) Explain why the use of biofuels may help to reduce global warming.
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(ii) Explain one disadvantage of using biofuels to reduce global warming.
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Q10. The carbon cycle describes the movement of carbon within an ecosystem.
In this cycle, carbon neutral processes do not change the concentration of carbon dioxide in the atmosphere.
The table below shows the main sources and combustion products of some fuels.
(a) Place a cross in the box next to the names of the four fuels, shown in the table, that could be considered to be biofuels.
(1)
A biodiesel, ethanol, hydrogen, methane
B biodiesel, ethanol, hydrogen, propane
C biodiesel, ethanol, methane, propane
D biodiesel, hydrogen, methane, propane
*(b) Large areas of land may need to be cleared in order to produce biofuels. This might involve deforestation.
Discuss why the production of biofuels may not be carbon neutral.
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(c) Explain how the combustion products, from the burning of fuels, may lead to global warming.
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(Total for Question = 10 marks)
Q11.
The decomposition of leaves depends on the content of the leaves, the presence of certain microorganisms and a number of abiotic factors.
Leaves consist of a number of organic molecules, including lignin and cellulose.
(a) Place a cross in the box next to the groups of microorganisms that all cause decomposition.
A bacteria and fungi
B bacteria and viruses
C fungi and viruses
D bacteria, fungi and viruses
(b) An investigation was carried out into the effect of lignin content on the decomposition of leaves from different types of tree.
The lignin content of leaves from an ash tree was determined. A pile of ash leaves was collected and weighed. The leaves were left for 40 days and reweighed. The mean daily loss in mass was calculated.
This was repeated for leaves from five other species of tree. All six piles of leaves had the same starting mass.
The results of this investigation are shown in the graph below.
(i) A student made the following conclusions from the data.
Place a cross in the box next to the number of correct conclusions made by the student.
(1)
A none
C two
D three
(ii) Place a cross in the box next to the term that completes the following statement.
Each pile of leaves had the same mass to ensure the investigation was
(1)
A accurate
B precise
C reliable
D valid
(iii) Suggest what happens to the cellulose in these leaves during decomposition.
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(iv) The student repeated this investigation on sycamore leaves.
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(Total for question = 11 marks)
