Biology Unit 4 Flashcards - Populations

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What is 'Ecology?'
The study of the inter-relationships between organisms and their enviroment
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What are 'Biotic factors?'
Living - eg; competition and predation
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What are 'Abiotic factors?'
Non living - eg; temperature
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What is an 'Ecosystem' made up of?
All of the interacting biotic and abiotic features in a specific area
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What are the two major processes to consider within Ecosystems?
The flow of energy through the system and the cycling of the elements within the system
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What makes up a 'Population?'
Many species made up of many groups of individuals
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What is a 'Population?'
A group of interbreeding organisms of one species in a habitat
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What forms a 'Community?'
Populations of different species
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What is a 'Community?'
All the populations of different organisms living and interacting in a particular place at the same time
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What is a 'Habitat?'
The place where a community of organisms live, within an ecosystems there are many habitats
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What is a 'Microhabitat?'
Smaller units within each habitat, each with their own microclimate
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What is an 'Ecological niche?'
How an organism fits into the enviroment, where an organism lives and what it does there
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What does a 'Niche' include?
All the biotic and abiotic conditions required for an organism to survive, reproduce and maintain a viable population
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What is an important factor about 'Niches?'
No two species occupy the same niche
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What is 'Abundance?'
A study of habitats where it is neccessary to count the number of individuals of a species in a given space
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Name the 3 factors to consider when using 'Quadrats?'
The size of quadrat to use, the number of sample quadrats to record within the study area, the position of each quadrat within the study area
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Why is 'Random sampling' important?
To avoid bias in collecting data, to make sure the data is valid
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What's the best way to pick the coordinates for sampling?
Randomly generate them on a computer
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How do you use a 'Quadrat?'
Either randomly assign coordinates on a computer or randomly throw the quadrat in the sample area and record the number of species and individuals within it
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How is a 'Transect' carried out?
A line transect comprises of a string streched across the ground in a straight line, any organism over which the line passes is recorded
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What is used to measure 'Abundance?'
Random sampling with quadrats and counting along transects
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Explain how frequency can be used to measure 'Abundance'
Frequency is the likelihood of a particular species occuring in a quadrat, this is useful where a species such a grass is hard to count but does not provide information for the distribution of a species
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Explain how % cover can be used to measure 'Abundance'
% is the estimate of the area within a quadrat that a particular plant species covers, useful when a species is difficult to count
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What an advantage of using % cover?
Data can be collected rapidly and individual plants don't need to be counted, less useful where several species overlap
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What's the best way to obtain 'Reliable results?'
Ensure the sample size is large and many quadrats are used, the larger number of samples the more representative of the community as a whole will be the results
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Describe the 'Mark-release-recapture technique'
1) A known number of animals are caught 2) Marked in a way that doesn't harm them (eg; doesn't make them vulnerable to predators) 3) Release the organism back at place found 4) Recapture samples and count how many have been recaptured
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How do you calculate the 'Estimated popualtion size?'
Total number of individuals in the first sample X the total number of individuals in the second sample DIVIDED by the number of the marked individuals recaptured
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What assumptions does the 'Mark-release-recapture' rely on?
The captured individuals must have time to distribute amongst the other individuals, must not be during breeding season, few dealths within population, method of marking must not be toxic
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Name the 'Ethics' involved in fieldwork?
Organism must not be harmed, if it dies it must still be placed back in habitat, damage to habitat should be avioded, an amount of time should pass between the two capturings
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What makes up the 'Population size?'
The number of individuals in a population
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How many phases does a usual pattern of growth for a natural population show?
3
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What does a period of 'Slow growth' mean?
This is where initially small number of individuals reproduce to slowly build up their numbers
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What does a period of 'Rapid growth' mean?
Where the ever-increasing number of individuals continue to reproduce, the population size doubles during each interval of time
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What does a period of 'Stable growth' mean?
Where the population growth declines until its size remains stable
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What may the decline of a population be down to?
A decrease in food supply, disease, predation
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Describe how the abiotic factor of 'Temperature' effects a population?
Each species has a different optimum temperature which is best for it to survive in eg; enzymes in plants
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Describe how the abiotic factor of 'Light' effects a population?
It's the ulimate source for ecosystems as light is the basic necessity of life. For plants the rate of photosynthesis is determined by light intensity
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Describe how the abiotic factor of 'pH' effects a population?
Effects the actions of enzymes as each enzyme has an optimum temperature
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Describe how the abiotic factor of 'Water and humidity' effects a population?
Humidity affects the transpiration rates in plants and the evapouration of water from the bodies of animals
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What is competition between members of the same species called?
Intraspecific competition
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What is competition between members of different species called
Interspecific competition
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What could competition be for?
Resources for food, water, breeding sites, territory
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What determines the size of a population?
The availability of resources
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What is the competition exclusion principle?
If two populations are in competition for resources then one species will normally have the advantage and will begin reducing the size of the other, if this continues it will lead to a complete wipeout of the species
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What is the main reason for variation in populations?
Competition
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What is a 'Predator?'
Organism that feeds on another organism, known as prey
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What is 'Predation?'
Predation occurs when one organism is comsumed by another
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Describe the relationship between predator and prey and how it affects their populations
The predator consumes prey - reduces prey's population, the predator's population is reduced if not enough prey is consumed which increases the prey population so the cycle continues
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What 2 major events have led to an explosion in human population?
The development of agriculture and the industrial revolution
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What has caused a decrease in human population?
War, disease, famine
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What is 'Immigration?'
Where individuals join a population from outside
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What is 'Emigration?'
Where individuals leave a population
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How do you work out 'Population growth?'
(Births + Immigration) - (Deaths + Emigration)
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How do you work out 'Percentage population growth rate (in a given period)'
Population change during the period DIVIDED by population at the start of the period X 100
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What are 'Birth rates' affected by?
Economic conditions, Cultural and religious backgrounds, Social pressures and conditions, Birth control and political factors
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How do you work out the 'Birth rate?'
Number of births per year DIVIDED by total population in the same year X 1000
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What are the factor affecting 'Death rates?'
Age profile, Life expectancy at birth, Food supply, Safe drinking water and effective sanitation, medical care, natural disasters, war
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How do you work out the 'Death rate?'
Number of deaths per year DIVIDED by total population in the same year X 1000
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What is a 'Demographic transition?'
Where life expectancy is short and birth rates are high to where life expectancy is long and birth rates are low such as Europe
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What population type is 'Where birth rate and death rate are in balance so there is no increase or decrease in population?'
Stable population
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What population type is 'A high birth rate, giving a wider base to the population pyramid and fewer older people'
Increasing population
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What type of countries would you typically see a 'increasing population?'
Economically less developed countries
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What is the population type where there is 'a lower birth rate and a lower mortality rate leading to more elderly people'
Decreasing population
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Other cards in this set

Card 2

Front

What are 'Biotic factors?'

Back

Living - eg; competition and predation

Card 3

Front

What are 'Abiotic factors?'

Back

Preview of the front of card 3

Card 4

Front

What is an 'Ecosystem' made up of?

Back

Preview of the front of card 4

Card 5

Front

What are the two major processes to consider within Ecosystems?

Back

Preview of the front of card 5
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