What is a population?
a group of organisms of the same species living in one area at one time
How does a population form a new species?
due to isolation that prevents interbreeding
What is a sample
a small proportion of the total population
Why is sampling useful?
when the habitat is too large to count every organism
What are the two types of sampling
Random and Systematic
Random sampling is
selected by random to avoid researcher bias
Systematic sampling is
selected at fixed internals in the site to avoid missing out on sections of the habitat
Example of random sampling?
quadrat sampling
Example of systematic sampling?
Transect sampling
What are the errors of random sampling
it assumes individuals are evenly distributed which may over or underestimate the population
What is quadrat sampling
square frames to provide a sample
used for sessile (non-motile) organisms
randomly or systematically
What does a large standard deviation mean for sampling results
large variation, further away from the mean
CMRR sampling technique?
- Define and mark sampling area individuals
- Capture and Mark individuals
- Release and allow time for reintegration
- Recapture, counting marked and unmarked individuals (M + N)
- Calculate Lincoln’s Index
What is lincoln’s index
Population = M x N/R
M= all marked
N= number of organisms recaptured
R= number of marked organisms recaptured
What are the assumptions made by the Lincoln Index
Population size stays the same
Marks will not affect chances of survival
Marks will stay on throughout study period
Redistribution of marked individuals is random
What is carrying capacity
number of individuals of a species an ecosystem can support
Abiotic factors affecting carrying capacity
Temperature: affects metabolic rate
Light availability: affects photosynthesis
Soil mineral availability: affects ability to build organic molecules
Biotic factors affecting carrying capacity
Predation: limits energy for growth and reproduction as it is used to avoid predation
Disease: limit energy for growth and reproduction
Competition for resources: limits resources available for growth and reproduction
What is population density
no. of individuals present per unit area of habitat
What do density-dependent factors do?
keep a population at or below the carrying capacity via a negative feedback loop
When does an exponential curve occur
in an ideal environment
When does a logistic growth curve occur
when environmental pressures slow growth rates
When does a sigmoid growth curve occur
negative feedback affects population size
Three phases of a growth curve
exponential
- population growth
- no limiting factors
transitional
- as population grows so does competition for resources
- struggle for survival
- slower growth
plateau
- ecosystem at carrying capcity
-
1.1- Intro to Cells17
-
1.2- Cell Types29
-
1.3- Stem Cells18
-
1.4- Membrane Structure23
-
1.5- Membrane Transport29
-
2.1- Water25
-
2.2- Organic Compounds14
-
2.3- Carbohydrates14
-
2.4- Lipids36
-
2.5- Proteins17
-
3.1- Transcription20
-
3.2- Translation12
-
3.3- Gene Mutations42
-
3.4- DNA Replication11
-
3.5- Cell Division18
-
4.1- Respiratory Systems41
-
4.2- Circulatory system20
-
4.3- Immune System44
-
4.4- Nervous System31
-
4.5- Reproductive System45
-
5.1- Integration48
-
5.2- Regulation26
-
6.1- Plant Structure16
-
6.2- Transpiration17
-
6.3- Germination32
-
7.1- Evolution22
-
7.2- Natural Selection19
-
7.3- Classification30
-
7.4- Extinction35
-
8.1- Population29
-
8.2- Communities21
-
8.3- Habitats25
-
8.4- Ecosystems30
