3.4.1 Populations Flashcards
What is an abiotic factor?
Non-living factors such as temperature and oxygen availability that affect the distribution of living organisms
What is an Ecological Community?
All the living organisms in a defined area
What is a Population?
The total number of a single species living in a defined area e.g. Bladder wrack
What is a habitat?
The abiotic part of an ecosystem; the place where an organism lives e.g. Rocky shores
What is an Ecological Niche?
The role of an organism in a community
What is a quadrat?
A square frame used to measure the distribution of organisms along a transect.
What is species frequency?
Number of samples found/total number of samples * 100
What is percentage cover?
The percentage of each quadrat sample that the organism covers
What is a transect
A technique for measuring the influence of an environmental gradient on organisms
What is a community?
All the living organisms in a defined area e.g. Rocky Shore community
What is an ecosystem?
A reasonably self contained functional unit
What is interspecific competition?
Competition for resources between species
What is intraspecific competition?
Competition for resources within a species
What is a biotic factor?
Living factors like predators and competition that affect the distribution of organisms in the ecosystem
How does temperature affect variation in population size?
Every species has optimal temperature, further away from that optimal temperature, the smaller number that can survive. Too high and enzymes denature, too low and enzymes slow down too much
How does light affect the variation of population size?
Light intensity affects the rat for photosynthesis. Faster photosynthesis means bigger populations for plants, so more food for animals, so bigger population for animals.
How does pH affect variation in population size?
Affects enzyme action. The closer to optimal pH, the bigger the population will be
How does water and humidity affect the variation in population size?
Only organisms adapted to dry conditions can survive where water is scarce and the air is dry. Humidity affects transpiration in plants and evaporation of water from the bodies of animals.
How does interspecific competition affect the variation in population size?
If two species are competing, the one with the advantage will grow in size, while the other will diminish
How does intraspecific competition affect variation in population size?
The higher the availability of resources, the larger the population because as they don’t have to compete
What is Random Sampling?
A method of sampling which reduces bias using random coordinates
What is Mark release recapture and how can it be used to investigate population size?
A method used in ecology used to estimate population size by capturing, marking releasing, and recapturing. Upon a random recapture the number of marked organisms can be used to calculate a Lincoln index to estimate the overall size
What is systematic sampling?
Sampling at regular intervals
Ethics of mark release recapture?
Can distress or harm the animal.
What can be used to analyse data to investigate populations?
Statistics and Kite a Diagrams
Describe how you could use the mark-release-recapture method to estimate the number of a species
Capture, mark and release
Method that does not harm the animal
Leave sufficient time for the animals to then randomly distribute
Population = number in the first sample x number in second sample divided by number of marked lizards recaptured
What is the formula for birth rate?
Number of births in a year x (1000/total population that year)
What is the formula for death rate?
Number of deaths in a year x (1000/total population that year)
What is the formula for percent growth?
(population increase during year/population at the start of the year) x100
What changes occur in the birth and death during demographic transition?
Birth and Death rate both fall, then level out/stabilise
What changes occur in population size over the course of demographic transition?
Population increases then levels off/stabilises
Suggest reasons why men’s life expectancy is lower than women’s
Stress, Obesity, War, Less likely to visit the doctor, Sex-linked diseases
What do different age pyramid shapes indicate?
- Wide base = high birth rate
- Quick narrowing = short life expectancy
- Wide top = Low death rate/long life expectancy
How can you read life expectancy off of a survivor curve?
Reading off the age that 50% of people survive.
