The figure below shows an example of a tool that can be used to help ecologists identify the organisms present within an ecosystem.
State the name of this tool.
Use the tool in part (a) to identify the organism shown in the figure below.
Did this page help you?
Distinguish between species richness and species diversity.
Did this page help you?
1 markSome ecologists captured a random sample of 100 deer and marked them with ear tags.
They then release the marked deer back into the population and allowed them to mix with the unmarked deer.
After a set period of time, the ecologists recaptured a random sample of 50 deer and found that 10 of them were marked.
Using the Lincoln Index, estimate the population size of the deer.
Outline one limitation of using the capture-mark-recapture method.
Did this page help you?
List three abiotic factors that can be measured in an aquatic ecosystem.
Did this page help you?
The figure below shows the data for a wolf population and the amount of suitable habitat that is available to the wolves.
Suggest one possible method for estimating the wolf population size.
Outline two reasons why collecting this type of data on wolves might be challenging.
Did this page help you?
Lichens are organisms that grow well on stone walls in unpolluted air. Lichens grow less well in polluted air.
Car exhaust fumes contain sulfur dioxide that pollutes air.
A scientist investigates the effect of pollution by cars in a city.
This is their method:
Measure the percentage area of a stone wall in the city centre covered by lichen
Repeat this measurement at different distances from the city centre
The table shows their results.
DIstance from city centre in km | Percentage area covered by lichen (%) |
0 | 0 |
2 | 6 |
4 | 20 |
6 | 30 |
8 | 50 |
10 | 64 |
12 | 70 |
Explain the results shown in the table.
Describe a method to measure the percentage of a stone wall covered by lichen.
Did this page help you?
Use the dichotomous key provided to identify the organisms below.
KEY | ||
1 (a) | Body is completely or partly covered in a shell | Go to 2 |
(b) | Body is not completely or partly covered in a shell | Limax flavus |
2 (a) | Shell is attached to rocks by thin threads | Mytilus edulis |
(b) | Shell is not attached to rocks by thin threads | Go to 3 |
3 (a) | Shell is a spire that comes to a point | Buccinum undatum |
(b) | Shell is not a spire that comes to a point | Go to 4 |
4 (a) | Animal has tentacles | Nautilus pompilius |
(b) | Animal has 2 tentacles | Planorbis planorbis |
Identify three limitations of using dichotomous keys for identifying organisms.
Did this page help you?
A group of students compares the distribution of plant species in two fields using the following method:
Use random sampling
Use a 0.5 m × 0.5 m quadrat
Count the number of each species in a quadrat
Repeat this method for five quadrats in each field
The tables below show the students’ results.
Species | Field A | ||||||
Number of plants in each quadrat | Number of plants per m2 | ||||||
First | Second | Third | Forth | Fifth | Mean | ||
Dandelion | 7 | 0 | 6 | 3 | 4 | 4 | 16 |
Buttercup | 2 | 1 | 0 | 3 | 2 | 2 | 6 |
Violet | 1 | 0 | 2 | 1 | 2 | 1 | 5 |
Heather | 2 | 3 | 1 | 2 | 1 | 2 | 7 |
Species | Field B | ||||||
Number of plants in each quadrat | Number of plants per m2 | ||||||
First | Second | Third | Forth | Fifth | Mean | ||
Dandelion | 7 | 3 | 2 | 1 | 2 |
|
|
Buttercup | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Violet | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
Heather | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
i)
Describe how the students would obtain random samples from each field.
[2]
ii)
Calculate the mean number of dandelions per quadrat in field B.
[1]
iii)
Calculate the number of dandelions per m2 in field B.
[1]
Describe the differences in species distribution in field A and field B.
Did this page help you?
Explain how a variety of ecological data collection methods could be used to show how an ecosystem changes as a result of human activity.
Did this page help you?
Evaluate methods for estimating biomass and energy at different trophic levels in ecosystems.
Did this page help you?