Interactions between organismsIB MYP Sciences: Topic test

20 questions, 54 marks

IB MYP Sciences

Interactions between organisms topic test

Total 54 marks

Name

Class

Date

1
On the Arctic tundra of northern Russia, willow shrubs are eaten by arctic hares and by lemmings. Arctic foxes eat both hares and lemmings, and snowy owls eat lemmings. Bacteria and fungi break down the remains of dead plants and animals.
(a)
What is the role of the willow shrubs in this community?
[1 mark]
AConsumer
BProducer
CDecomposer
DPredator
(b)
A disease kills most of the arctic foxes. What is the most likely short-term effect on the community?
[1 mark]
AThe snowy owls die out
BThe number of willow shrubs increases
CThe number of lemmings falls
DThe number of arctic hares rises
(c)
Write a food chain of three organisms from this community, and state what the arrows in a food chain show.
[2 marks]
Total for question 1: 4 marks
2
In a grassland in Patagonia, grass stores 40 000 kJ of energy from the Sun in each square metre every year. Guanacos, which are herbivores, eat the grass, and pumas eat the guanacos. Of the 40 000 kJ stored in the grass in each square metre, 3600 kJ is passed to the guanacos each year.
(a)
What is the original source of the energy in this food chain?
[1 mark]
AThe grass
BThe guanacos
CThe Sun
DThe soil
(b)
Which is a way in which energy is lost between the grass and the guanacos?
[1 mark]
ASome energy is transferred to the surroundings as heat by the guanacos' respiration
BSome energy is destroyed
CSome energy is returned to the Sun
DSome energy is changed into carbon dioxide
(c)
Calculate the percentage of the energy stored in the grass that is passed to the guanacos. Show your working.
[2 marks]
Total for question 2: 4 marks
3
On a dairy farm in Iowa, USA, maize is grown to feed the cows. Tractors on the farm burn diesel, and the farm buildings are heated with gas.
(a)
Describe how a carbon atom in a molecule of carbon dioxide in the air can become part of a cow, and how it can later return to the air.
[3 marks]
(b)
Explain how burning fuels such as diesel and gas has changed the carbon cycle, and what effect this has on the climate.
[4 marks]
Total for question 3: 7 marks
4
A marine science class in Cornwall, UK, studies a rocky shore where barnacles and seaweeds live between the high-tide line and the low-tide line. Visitors collect shellfish and walk over rock pools, and the local council is considering making part of the shore a protected conservation zone in which collecting is banned.
(a)
Design an investigation using a transect and quadrats to find out how the number of barnacles changes from the high-tide line to the low-tide line. Include a hypothesis with a reason, the variables, the method and a safety precaution.
[6 marks]
(b)
Evaluate the council's proposal to ban collecting and protect part of the shore, and reach a justified conclusion.
[6 marks]
Total for question 4: 12 marks
5
In the 1800s many trees in the industrial town of Manchester, England, were covered in black soot from factories. Moths of one species rest on tree trunks during the day, where birds hunt them. Before the soot, most of the moths were pale and speckled. Within fifty years most of the moths in the town were dark.
(a)
What type of variation is shown by the colour (pale or dark) of the moths?
[1 mark]
ADiscontinuous variation
BContinuous variation
CVariation caused only by the soot
DNo variation
(b)
Which of these is needed for natural selection to take place?
[1 mark]
AAll the individuals are identical
BPlenty of food for every individual
CInherited variation between individuals
DA change in an individual's genes because it needs to survive
(c)
Explain why dark moths became more common in Manchester.
[2 marks]
Total for question 5: 4 marks
6
Off the coast of Newfoundland, Canada, huge fishing boats caught so many cod each year during the 1980s that the number of cod fell to a tiny fraction of what it had been. Cod eat smaller fish and are eaten by seals.
(a)
What is meant by overfishing?
[1 mark]
AFishing only in the winter
BCatching only the largest fish
CUsing nets with large holes
DCatching fish faster than the population can reproduce
(b)
Which measure would best help the cod population to recover?
[1 mark]
AUsing bigger boats
BSetting a limit on the number of cod that can be caught
CIntroducing a new fish species to the area
DCatching only the young cod
(c)
Explain how the fall in the number of cod could affect the seals and the smaller fish that cod eat.
[2 marks]
Total for question 6: 4 marks
7
A single oak tree in an English wood supports about 20 000 caterpillars. The caterpillars are eaten by about 40 blue tits, and one sparrowhawk feeds on the blue tits.
(a)
Explain why a pyramid of numbers for this food chain is not a pyramid shape, but a pyramid of biomass would be.
[3 marks]
(b)
Explain why food chains rarely have more than four or five trophic levels.
[4 marks]
Total for question 7: 7 marks
8
A conservation team in Scotland surveys a nature reserve of heather moorland that covers 2000 m². Heather provides food and shelter for red grouse, and sheep also graze on the moorland. Some people want to plant trees on part of the moorland to store carbon and restore woodland, but this would reduce the area available for grouse and sheep, which provide income for local farmers.
(a)
The team counts the heather plants in five randomly placed quadrats, each of area 0.5 m². The counts are 12, 8, 15, 10 and 5. Calculate an estimate of the total number of heather plants on the reserve, showing your working, and evaluate how reliable your estimate is.
[6 marks]
(b)
Evaluate the proposal to plant trees on part of the moorland, and reach a justified conclusion.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).