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IB Biology C4.1: Pop. & Commu. — Practice Questions & Answers
IB Biology C4.1 Populations and communities study notes: estimating population size, carrying capacity, sigmoid growth, and species interactions.
Here are 10 practice questions with full answers and explanations.
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Practice questions with answers
1
Multiple choice
What is a population?
Interacting groups of organisms of the same species living in an area.
All organisms living in an area.
All species living in an ecosystem.
A group of different species interacting.
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Why A population is a group of interbreeding organisms of one species living together in an area.
2
Multiple choice
What is reproductive isolation used for?
Distinguishing one population of a species from another.
Estimating population size.
Determining carrying capacity.
Modelling population growth.
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Why Reproductive isolation prevents interbreeding, distinguishing one population or species from another.
3
Multiple choice
Why is random sampling used to estimate population size?
To avoid counting every individual.
To increase accuracy.
To count every individual quickly.
To avoid sampling error.
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Why Random sampling estimates population size without the impracticality of counting every individual.
4
Multiple choice
What is sampling error?
The difference between the estimate of population size and the true size of the whole population.
Errors in data collection.
Errors in data analysis.
Errors in experimental design.
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Why Sampling error is the difference between the sample-based estimate and the true population size.
5
Multiple choice
What type of organisms is random quadrat sampling used for?
Sessile organisms.
Motile organisms.
Microorganisms.
Aquatic organisms.
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Why Random quadrat sampling suits sessile, non-motile organisms like plants that stay within the frame.
6
Multiple choice
What does the standard deviation of a mean indicate?
The variation and how evenly the population is spread.
The average population size.
The total number of species.
The carrying capacity.
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Why Standard deviation measures the spread of data around the mean, indicating variability in the population.
7
Multiple choice
What method is used to estimate population size for motile organisms?
Capture–mark–release–recapture.
Random quadrat sampling.
Direct counting.
Remote sensing.
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Why Capture-mark-release-recapture estimates the size of mobile animal populations.
8
Multiple choice
What is the Lincoln index used for?
Estimating population size.
Measuring species diversity.
Determining carrying capacity.
Modelling population growth.
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Why The Lincoln index uses mark-recapture ratios to estimate the total size of a mobile population.
9
Multiple choice
What is carrying capacity?
The maximum population size that an environment can support.
The minimum population size.
The rate of population growth.
The rate of population decline.
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Why Carrying capacity is the maximum population size the environment can sustain given its resources.
10
Multiple choice
What are density-dependent factors?
Factors that influence population size based on population density.
Factors independent of population density.
Factors that cause exponential growth.
Factors that cause random fluctuations.
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Why Density-dependent factors have effects that intensify as population density increases.
Key terms in Pop. & Commu.
Population: All the organisms of the same species living in the same area at the same time and able to interbreed.
Community: All the populations of different species living and interacting together in the same area.
Carrying capacity: The maximum population size that an environment can support sustainably over the long term.
Sigmoid growth curve: The S-shaped curve of population size against time, with exponential, transitional and plateau phases.
Intraspecific competition: Competition for resources between members of the same species; the main factor limiting a population near its carrying capacity.
Interspecific competition: Competition for shared resources between members of different species whose needs overlap.
Mutualism: A symbiotic interaction in which both participating species benefit, such as <em>Rhizobium</em> and a legume.
Parasitism: An interaction in which the parasite benefits at the expense of the host, which is harmed.
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