Exam code: X807 75
Seals and dolphins compete for food.
Which row in the table describes the interaction between these organisms?
Type of competition | Type of factor | |
A | intraspecific | biotic |
B | intraspecific | abiotic |
C | interspecific | biotic |
D | interspecific | abiotic |
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The diagram shows part of a food web in a pine forest.
Complete the table by giving one example of each type of organism from the food web.
Type of organism | Example |
Producer | |
Predator |
Use the words ‘increases’, ‘decreases’, or ‘stays the same’ to suggest what might happen to the size of the squirrel population if all the foxes were removed.
Explain your answer.
Squirrel population.......................................................................
Explanation....................................................................................
State the term used to describe the role of an organism within its community.
The table shows some features of fungi commonly found in Scotland’s pine forests.
Fungus | Maximum cap size (cm) | Cap colour | Stem colour |
Velvet rollrim | 20 | mid brown | dark brown |
Sickener | 10 | bright scarlet | |
Earpick fungus | 2 | dark brown | dark brown |
Pelargonium bonnet | 1 | dark brown | dark brown |
Pinewood gingertail | 2 | bright brown | brown |
Use the information in the table to complete the key.
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The diagram represents part of a woodland food web.
Which statement is true for the organisms in the food web?
Owl and stoat are in intraspecific competition.
Bank vole and shrew are in interspecific competition.
Ladybird is both predator and prey.
Greenfly is a producer.
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1 markThe graph shows the changes in population size of a predator and its prey over 20 years.
The difference in the population sizes of the predator and its prey when each population was at its maximum is
6000
16 000
22 000
50 000
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In an ecosystem, a niche is defined as the
place where an organism lives
total number of one species living in a community
role an organism plays within a community
total number and variety of organisms.
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The food web represents a marine ecosystem in the west coast of Scotland.
Give an ecological term that describes the sea urchins.
Pollution from microplastics has led to a decline in the mussel population.
Predict the effect of a decrease in mussels on the sea otter population and explain your answer.
Effect on sea otter population................................................................
Explanation..............................................................................................
1 markMarine biologists investigated the effect of salt concentration on the number of microplastic particles in mussel body tissue.
The results are shown in the table.
Salt concentration (ppb) | Number of microplastic particles per 1 g of mussel body tissue |
31 | 4 |
33 | 8 |
36 | 20 |
A mussel with a mass of 5 g was found to contain 20 particles of microplastics in its body tissue.
Identify the salt concentration the mussel was found in.
................................ppb
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Some feeding relationships of organisms in a woodland ecosystem are shown in the food web.
Due to extreme weather conditions, the populations of tree-living and ground-living insects were greatly reduced.
This could lead to:
an increase in small birds and a decrease in spiders
an increase in squirrels and a decrease in spiders
a decrease in nuts and leaves and an increase in small birds
a decrease in weasels and an increase in owls
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3 marksA student set up four Petri dishes of equal size to investigate competition in cress seeds of the same species. The seeds were scattered on moist filter paper and left to germinate (grow) in the dark.
(i) Identify a variable, not already mentioned, that should have been kept the same for each dish.
[1]
(ii) The number of seeds germinating in each dish was counted.
The table shows the results.
Dish | Seeds per dish | Number of germinating seeds | Germinating seeds (%) |
A | 50 | 45 | 90 |
B | 100 | 80 | 80 |
C | 150 | 60 | |
D | 200 | 60 | 30 |
Complete the table by calculating the number of germinating seeds in dish C.
[1]
(iii) Competition was greatest in dish D.
Explain why this conclusion was drawn.
[1]
Name the type of competition that occurs among these germinating seeds.
Explain why competition in ecosystems occurs.
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