Science questions, chapter 9
Earth
44 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.
Section A: objective questions
12 marksChoose the best answer for each question.
1
Which component of the Earth system is the life zone, made up of humans, animals, plants and microorganisms?
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B
The biosphere is the life zone. The geosphere is rock and soil, the hydrosphere is water and the atmosphere is air.
2
In which layer of the atmosphere is the ozone layer found?
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D
The ozone layer is in the stratosphere (13 – 50 km). It absorbs harmful ultraviolet rays from sunlight.
3
Diagram 1 shows the layers of the atmosphere. In which layer do meteorites burn up and get destroyed?
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A
Meteorites burn up in the mesosphere (50 – 80 km), which is layer R. Q is the stratosphere, S the thermosphere and T the exosphere.
4
Why is it difficult for plants to live in the midnight zone of the ocean?
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C
Plants need light. The midnight zone has little or no light. Only the surface zone receives enough light for plants.
5
Earth is the only planet in our Solar System that is suitable for life. Which statement explains this?
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D
Earth is not too near and not too far from the Sun, so its temperature is suitable. It also has water and oxygen.
6
A rock has many layers and contains fossils. What type of rock is it most likely to be?
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B
Sedimentary rocks form from compressed layers of deposited material, so they are layered and may contain fossils. Igneous rocks form from hot magma and have no fossils.
7
Diagram 2 shows lava flowing out of a volcano. What type of rock will form at P?
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A
When lava cools and freezes it forms igneous rock (textbook Summative Practice 9, Q5).
8
Which of the following is an endogenic process?
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C
Endogenic processes are caused by forces from within the Earth, e.g. mantle convection, magma activity and plate tectonics. The other three happen on the surface (exogenic).
9
Diagram 3 shows a device placed on the slope of a hill. It has an acoustic sensor. What does it give an early warning of?
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B
This is the landslide detector. When the slope moves, the gravel makes sound that the acoustic sensor detects. A different device, placed at the shoreline, gives tsunami warnings via satellite.
10
Diagram 4 shows when some organisms first appeared on Earth. How many million years after the Earth was formed did seaweed first appear?
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D
Earth formed 4500 million years ago and seaweed appeared 1000 million years ago: 4500 − 1000 = 3500 million years later.
11
Which of the following is a metallic mineral?
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A
Iron ore, tin and gold are metallic minerals. Coal and petroleum are non-metallic minerals.
12
The water at the hot spring in Sungai Klah, Perak is hot even at night. Which statement explains this?
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C
This is the hydrothermal process: underground water (an aquifer) is heated by heat from the Earth (magma).
Section B: structured questions
32 marksAnswer all questions. Write your answers in the spaces provided.
13
Diagram 5 shows the layers of the Earth. Name the layers P, Q, R and S.
[1 mark]
(a)Layer P
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Crust
P is the thin outermost layer.
[1 mark]
(b)Layer Q
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Mantle
Q is the thick layer under the crust.
[1 mark]
(c)Layer R
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Outer core
[1 mark]
(d)Layer S
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Inner core
S is at the centre of the Earth.
14
Diagram 6 shows the layers of the atmosphere.
[1 mark]
(a)In which layer does the aurora occur?
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S
The aurora occurs in the thermosphere (80 – 480 km).
[1 mark]
(b)Communication satellites orbit the Earth in which layer?
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T
Satellites orbit in the exosphere (480 km and above).
[2 marks]
(c)Layer Q contains the ozone layer. Explain why the ozone layer is important to living things.
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- The ozone layer absorbs (harmful) ultraviolet rays from sunlight1
- So less ultraviolet rays reach living things / protects living things from the harmful effects of UV rays1
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15
Diagram 7 shows the air pressure at different altitudes.
[1 mark]
(a)What is the air pressure at an altitude of 10 km?
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- 26 kPa (accept 25 – 27 kPa)1
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[1 mark]
(b)Describe the relationship between altitude and air pressure.
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- The higher the altitude, the lower the air pressure1
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[1 mark]
(c)Calculate the fall in air pressure from sea level (0 km) to 5 km.
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- Readings about 101 kPa and 54 kPa; fall = 101 − 54 = 47 kPa (accept 45 – 48 kPa from the student's readings)1
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[1 mark]
(d)Explain why mountain climbers find it difficult to breathe near the top of a high mountain.
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- Air pressure is low / air is thinner at high altitude, so there is less oxygen in each breath1
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16
Diagram 8 shows the rock cycle. Some labels have been replaced by X and Y.
[1 mark]
(a)Name process X, which changes magma into igneous rock.
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- Cooling and freezing (of magma / lava)1
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[2 marks]
(b)Process Y changes sedimentary rock into metamorphic rock. State two factors needed for process Y.
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- (Very) high pressure1
- (Very) high temperature / heat1
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[1 mark]
(c)Salina found a rock at the mouth of a river. It is hollow, layered and contains fossils. What type of rock is it?
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Sedimentary rock
Layers, hollows and fossils are features of sedimentary rock (textbook Summative Practice 9, Q6).
17
Classify each process as exogenic or endogenic.
[1 mark]
(a)Rocks break up because of changes in temperature and rainwater.
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Exogenic
Weathering happens on the surface.
[1 mark]
(b)Two plates of the Earth's crust move apart.
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Endogenic
Plate tectonics is caused by forces inside the Earth.
[1 mark]
(c)Soil moves down a slope because of gravity.
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Exogenic
Mass and land depletion happens on the surface.
[1 mark]
(d)Name two agents that cause erosion.
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- Any two: water, wind, waves [both needed for 1 mark]1
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18
Diagram 9 shows when some organisms first appeared on Earth.
[1 mark]
(a)When did fish first appear on Earth?
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- 500 million years ago1
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[1 mark]
(b)How many million years after the first fish did flowering plants appear?
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- 500 − 130 = 370 million years1
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[1 mark]
(c)The age of the Earth is about 4.5 billion years. What did scientists use to estimate this?
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- Meteorites1
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[1 mark]
(d)State one importance of fossils to scientists today.
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Any 1 points
- Show how plant and animal species have evolved over millions of years1
- Give information about species that have become extinct1
Tick each point you got.
19
Read the news report.
Bauxite pollution in Kuantan
Residents complain about bauxite pollution near Bukit Goh, Gebeng and Kuantan Port. Uncontrolled mining has dirtied the main road, bauxite dust pollutes the air and the river is polluted. Bauxite is red soil rich in aluminium.
Residents complain about bauxite pollution near Bukit Goh, Gebeng and Kuantan Port. Uncontrolled mining has dirtied the main road, bauxite dust pollutes the air and the river is polluted. Bauxite is red soil rich in aluminium.
[3 marks]
(a)A company says the mining should continue without any control because aluminium is valuable to the economy. Do you agree? Give your opinion and two reasons.
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Any 3 points
- Opinion: disagree — mining should continue only if it is controlled / planned [1 mark, must have a reason to score]1
- Bauxite dust pollutes the air and causes health problems (e.g. breathing problems)1
- Rivers are polluted, harming aquatic life and the water supply1
- Soil is exposed, causing erosion / flash floods / dirty roads1
- Mineral supply is limited, so it must be used wisely1
Tick each point you got.
[1 mark]
(b)Uncle Yatim is a farmer. His son advises him not to spray pesticides excessively. Why?
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- Excess pesticide pollutes surface water (rivers) / leaches into underground water and pollutes it1
Tick each point you got.
20
Cameron Highlands often has landslides on its steep hill slopes. Diagram 10 shows a slope after a landslide.
[3 marks]
(a)Suggest a device that could warn the villagers before a landslide happens. Explain how it works and where it should be placed.
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Any 3 points
- Device: landslide detector with an acoustic sensor (or a tilt / movement sensor, or a rain gauge linked to an alarm)1
- Placement: buried in / on the slope of the hill above the houses or road1
- How it works: when the slope starts to move, the gravel rubs and makes sound / movement that the sensor detects1
- It sends a signal / sounds an alarm or SMS so people can move away early1
Tick each point you got.
[1 mark]
(b)Suggest one other step (not a device) to reduce the risk of landslides on the slope.
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- Plant trees / grass on the slope; avoid clearing forest on steep slopes; build retaining walls or proper drains1
Tick each point you got.