EOY Answers

REMARKS : PLS WRITE IN BIGGER FONT SIZE!!! 


Section A (13 marks)

1		A group of students wanted to investigate weather conditions in Changi Beach. Study Fig.1 which shows the data that they have collected on 1st July 2017. Air pressure (mb) Relative Humidity (%) Temperature (°C) 8am 1001 39 27.3 9am 1000 37 28.6 10am 1000 36 28.5 11am 998 31 29.0 12pm 996 30 25.5 1pm 997 30 32.8 2pm 999 32 32.4 3pm 1006 33 31.5 4pm 1008 35 30.8 5pm 1010 38 30.1 Fig. 1
	(a)	Name the instruments that the students can use to measure air pressure and relative humidity.                                                                                                                           [2]
		-        Barometer, Sling Psychrometer (1 person spelling mistake!)
	(b)	The teacher pointed out that there is an error made by the students in the collection of temperature data at 12pm. Suggest reasons that could account for the inaccuracies in the data collected.                                                                                                                                             [3]
		-        Mistakes made in recording of data (Human error)/ Parallax error (SPELLING!) -        The students held the thermometer too close to their body which affected the results collected -        The students held the bulb of the thermometer which affected the temperature results Note : Sling psychrometer doesnt measure temperature!!
	(c)	Suggest improvements students could make if they were to carry out the investigations again to achieve more accurate data.                                                                            [3]
		-        Have 2 set of data collected, take the average to get more accuracy -        Increase the frequency in the time intervals eg every half an hour -        Use different set of instruments to confirm readings eg sixes thermometer and digital thermometer -     Get another student to record to ensure more accuracy -  Sling psychrometer should be held one arm's length away from the body to ensure that body heat does not affect the temperature -     Sling psychrometer should be swung consistently / at a steady pace for accurate data. NOT ACCEPT : Remain at the same spot / move to an open area(Beach is already an OPEN area!) /
	(d)	State a suitable hypothesis which could link air pressure to temperature.                     [1]
		Air pressure increases when temperature decreases / Air pressure decreases when temperature increases [2m for hypothesis]
	(e)	One of the students observed that ‘temperature and pressure increases at the same time’. How much does the data collected support the guiding question above? Explain why this is so.                                                                                                                 [4]
		-        No -        From 8am – 1pm, air pressure decreases from 1001 mb to 997 mb, at the same time the temperature increases from 27.3°C to 32.8°C. [2] -        From 1pm – 5pm, air pressure increases from 997mb to 1010mb, at the same time the temperature decreases from 32.8°C to 30.1°C [2] -     Yes: From 12-1pm, both temperature and air pressure increases from 996 to 997mb and 25.5 to 32.8.

Section B (12 marks)

2		Study Fig. 2 below which shows the relationship b Temperature °C                  Altitude (meters) Fig. 2
	(a)	With reference to Fig. 2, describe the relationship of temperature and altitude. Explain why temperature changes with altitude.                                                                                               [3]
		-        Temperature decreases with the increase in altitude. -        At higher up in the atmosphere, the distance to the surface of the earth increases. The earth’s surface is heated by the sun and traps solar energy at low altitude. -        Air that is nearer to the earth’s surface absorbs more heat from longwave radiation than air at higher altitudes. -        Air is also less dense at higher altitudes, therefore it results in lower temperatures as it has less ability to absorb heat than the denser air at sea level. Accept any 3 possible answers. Good answers : Jon, Kaiwan, Chikin

	(b)	Explain how relief rain is formed.                                                                                                   [3]
		-        Warm moist air passes over the sea and is forced to rise over landforms such as a mountain range -        At the windward side, air cools as it rises. At dew point temperature, condensation occurs and falls as rain when the water droplets are heavy enough. -        By the time the air moves to the leeward side, air is dry and no rain falls.

Note: Majority answered it very well. A few students only write about convectional rainfall 

	(c)	‘Deforestation is the main human cause of global warming.’ How far do you agree with this statement? Explain your answer with relevant examples.                                        [6]
		Introduction : Take a stand (Agree/Disagree) Compulsory factor: Deforestation Other factors: Burning fossil fuels, Changing land use Factor Description Examples Deforestation is the loss of forests due to the removal or clearance of trees in forested areas. Deforestation cause increase in levels of carbon dioxide as fewer trees absorb carbon dioxide. When soil is exposes to sunlight, the carbon in soil reacts with oxygen to produce carbon dioxide, resulting in higher temperatures. Australia lost more than 2,500,000 hectares of forest between 2005 and 2010. Burning of fossil fuel will release huge amount of carbon dioxide when burnt. The burning of petroleum, coal and natural gas is necessary to power energy for the world. However this contributes to greenhouse gases in the atmosphere. Large consumers of fossil fuels include China, the USA, Canada and the United Kingdom. In Singapore, most of our electricity is generated by fossil fuels. Agriculture which is the practice of cultivating land, producing crops and raising livestock, is the third highest contributor of greenhouse gases. Organic matter such as dead leaves and manure releases methane during decomposition. The use of inorganic fertilizers increase the amount of nitrous oxide in the soil. In Argentina, methane from cow accounts for more than 30% of the country’s total greenhouse emissions. Industrialization produces goods and services which involves burning of fossil fuels. Greenhouse gases are released as a by-product when goods are produced. The largest carbon dioxide emissions from industrial processes are found in North and Central America, Europe and Asia. In conclusion, there are other human causes of global warming besides deforestation. Various factors adds up together and contributes to the production of greenhouse gases. Therefore humans must use more environmentally friendly method in their development to reduce the amount of greenhouse gases. Level 1 (0 - 2 marks) At this level answers will be generalized or with minimal support if any stand were given at all. Reasoning rather weak and expression may be unclear. A basic answer that has little development. Award L1/1 for answer limited to simple listing of one or two factors. Award L1/2 for answer with description of one or two factors. Level 2 (3 - 4 marks) Disagreement and agreement will be supported by appropriate detail. Or, both agreement and disagreement are considered, but support is patchy so that the answer is not full.  Good reasoning and logic in parts of the answer with good expression in places. Award L2/3 for answer with explanation of at least two factors. Award L2/4 for answer with explanation of at least two factors with at least ONE example given. Level 3 (5 - 6 marks) At this level answers will be supported by sound knowledge. Both agreement and disagreement are considered and well supported.  Reasoning is clear and logical with good expression of language. Award L3/5 for answer with explanation of at least two factors, with at least TWO examples given. Award L3/6 for answer with explanation of at least two factors, with a good conclusion stated.

Section C (25 marks)

3		Fig. 3 below shows the cross section of a volcano that has recently erupted. C   B B A                                                                        Fig. 3
	(a)	Label the parts below and describe its features in the volcano.                                       [3]
		(i)	Label part A : Vent Description : An opening exposed on the earth's surface where volcanic material is emitted.
		(ii)	Label part B : Layers of ash and lava Description : Formed when magma cools and solidifies. New layer forms above it with every successive eruption.
		(iii)	Label part C : Crater Description : A large bowl shape depression formed during a volcanic eruption when the top is blown off. 0.5m each Note : Many wrote 'hole' ' opening'. Try to use the right terms.
	(b)	Describe the differences between the characteristics of a shield and a stratovolcano. [3]
		Slope -        The shield volcano has gently sloping sides and has a broad summit whereas the stratovolcano has steep sloping sides and has a small summit. Explosivity -        The shield volcano is less explosive compared with the stratovolcano that is more explosive during an eruption. Viscoscity of lava -        The shield volcano has less viscous lava with lower silica content whereas the stratovolcano has more viscous lava with higher silica content. (1m each) Note : Accept if height comparision is used. Some cannot spell SHIELD! Please write point by point in comparision. Markers look for points that are the same in the comparision.
	(c)	Describe and explain two life threatening risks experienced by people staying near a volcano.                                                                                                                               [4]
		Destruction by volcanic materials -        Lava is released during an eruption with a temperature of 500°C to 1400 °C. -        Pyroclasts (ash, rock fragments and volcanic bombs) are produced which are life threatening. -        Breathing in such hot gases would burn the lungs of victims, leading to instant death. (Any 2 points) Landslides -        Occurs due to the structural collapse of a volcanic cone. -        This obstructs the flow of rivers which causes floods, block roads, bury villages and farmlands. -        People may be trapped under buildings or buried under soil and may die of starvation or asphyxiation. (Any 2 points) Note : Must explain how it THREATENS PEOPLE and not just the impact. eg flight cancellation / air pollution. Perfect answer : Nadia, Sharifah, Xingyi, Tasmin
	(d)	Study Fig. 4 which shows a map of Hilo, a town in Hawaii. Fig. 4
		Using evidence from Fig. 4, explain how the tectonically active region of Hilo provides economic opportunities for its residents.                                                                         [4]
		-        The volcano farmers market in Fig. 4 shows that farmers stay near volcanoes as there are fertile soil in the area. [1] The lava and ash from the volcanic eruptions break down to form fertile soil which is favorable for agriculture. [1] -        The presence of gift shop, rainforest retreat and village lodge [1] reflects that tourists are attracted to the place. Therefore people would want to stay near volcanoes so that they can earn money from tourists. [1] Note : Xuan Chan and Wai Teng wrote both points with data from fig. 4. RETREAT is NOT FOR EVACUATION!!!!
	(e)	State and describe two factors that determine the severity of damages resulting from an earthquake. Support your answer with an example.                                                                             [5]
		Factor (Any 2) Elaboration Examples Population density The greater number of people staying in an area, the higher likelihood of damages incurred. Earthquake in Anchorage, Alaska in 1964 has a magnitude 9.2 on the Richter Scale. But only 115 people died as the area had a small and sparse population. Time of occurrence The time of the day that the earthquake occurs would affect whether people are more ready to evacuate compared with night when they are asleep. More than 2400 people died when an earthquake occurred a couple of hours after midnight in the Sun Moon Lake Region in Taiwan in 1999. NOTE : MANY CREATED THEIR OWN YEAR THAT THE EQ OCCURED!! Level of preparedness The education and training of the population would help to evacuate residents to safe grounds. In Japan, students are taught how to react when the earthquake warning signal goes off. They are to crouch under the nearest table, so as to prevent falling objects from injuring them Distance from epicenter The point on earth’s surface that earthquake occurs affects the number of casualties. Closer to epicentre results in greater fatality. During the 2011 Christchurch earthquake in New Zealand, the epicentre was in a town a few km away from the city centre. Thus, the city centre suffered more damages than areas further away from the city. Type of soil The soil with loose sediments would results in strong effects of seismic (earthquake) waves. In the 2011 Christchurch earthquake in New Zealand, many houses and buildings had to be abandoned. Due to liquefaction (soil turns to liquid like form because of pressure and stress) after the earthquake.
	(f)	‘Tsunamis pose the greatest risk to the population affected by an earthquake.’ Do you agree with this statement? Support your answer with examples and details.                 [6]

Introduction : Take a stand (Agree/Disagree)

Compulsory factor: Tsunamis

Other factor: Disruption of services, Fires, Landslides, Destruction of properties, Destruction of infrastructure, Loss of lives

Factor	Elaboration	Examples
Tsunami Threats	The movement of the sea floor during a large earthquake at subduction zones causes large amount of sea water to be displaced The waves rise in height towards the shore and crashes at the coast	In 2004, a 9.2 earthquake in Indian Ocean triggered a tsunami that damaged coastal communities in 12 countries. The tsunami waves were 4-39m high and went inland to 10km in western Sumatra.
Disruption of Services	Earthquakes can rupture gas and water pipes or electrical cables with the sudden force and jerk.	In 2004, an earthquake in Kobe, Japan disrupted electricity, gas and water supplies to the city’s 1.4 million residents.
Destruction of Properties	The shaking of the ground will loosen the soil and destabilize the foundation of the houses. This may cause properties to fall apart and destroyed many homes.	In 2011 Tohoku Earthquake in Japan, the tsunami travelled 10km inland and destroyed the houses and properties.
Loss of Lives	People may be killed by falling buildings and infrastructure. Many bodies were also found tapped under debris.	In 2010, Haiti Earthquake killed 300,000 people and left 1.3 million homeless.
Destruction of Infrastructure	Earthquakes may cause cracks to form in infrastructure such as roads and bridges. Transportation can be disrupted as it is unsafe to use the damaged roads.	In 1995, Kobe’s earthquake damaged many places in the city where it became inaccessible and difficult to reach.
Landslides occurrence	Landslides are rapid downslope movements of soil, rock and vegetation The earthquake destabilizes the slopes and cause the ground to give way	In 1970, an earthquake in Peru destabilised the slopes of Mount Huascaran and triggered a massive landslide. The landslide travelled at 160km/h and flatten the town within seconds. More than 18000 people died.
Fires breakout	Earthquakes may rupture gas pipes and this can provide fuel to start fires. This destroy houses and lives of people. Building and infrastructure are also burnt and damaged by the fires.	In 1995, an earthquake in Kobe, Japan caused extensive fires.

In conclusion, Tsunamis may not necessary be evident during all earthquakes as it depends if the earthquake occurs near to the sea, or if the affected area is in a coastal area. There are other more risky impact of an earthquake such as loss of lives, destruction of infrastructure and properties. Therefore countries lying in earthquake zones should be always prepared to evacuate in the event of a natural hazard.

Level 1 (0 - 2 marks)

At this level answers will be generalized or with minimal support if any stand were given at all.

Reasoning rather weak and expression may be unclear.

A basic answer that has little development.

Award L1/1 for answer limited to simple listing of one or two factor.

Award L1/2 for answer with description of one or two factor

Level 2 (3 - 4 marks)

Disagreement and agreement will be supported by appropriate detail.

Or, both agreement and disagreement are considered, but support is patchy so that the answer is not full. 

Good reasoning and logic in parts of the answer with good expression in places.

Award L2/3 for answer with explanation of at least two factors.

Award L2/4 for answer with explanation of at least two factors with at least ONE example given.

Level 3 (5 - 6 marks)

At this level answers will be supported by sound knowledge.

Both agreement and disagreement are considered and well supported. 

Reasoning is clear and logical with good expression of language.

Award L3/5 for answer with explanation of at least two factors, with at least TWO examples given.

Award L3/6 for answer with explanation of at least two factors, with a good conclusion stated.