19953499
Description
Flashcards by Janice Wright, updated more than 1 year ago
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Created by Janice Wright
over 4 years ago
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| Question | Answer |
| What is Ecology | It is the interactions of organisms with their physical and biological environments. |
| What is Population Ecology | It is the fluctuations in the size of a population and the factors both physical and social that cause these fluctuations |
| What is a biosphere | Is the part of the earth where living organisms are found |
| What is an ecosystem | It is made up of groups of different species/organisms that interact with each other |
| What is an organism | It is an individual form of life |
| What is a community | It is a group of different species that inhabit an environment |
| What is a species | It is a group of closely related organisms that are capable of interbreeding |
| What is an individual | Is a single organism capable of independent existence |
| What is a population | It is a group of organisms of the same species that occupy the same area that can breed freely with each other |
| What affects the size of a population (4 points) | 1) Natality - is the birth rate of animals or the production of seeds in plants 2) Mortality - is the death rate 3) Immigration - individuals move into a population and stay 4) Emigration - Individuals leave a population and do not return |
| What impacts the size of a human population (2 points) | 1) The birth rate - the number of births per 1000 people in a year 2) The death rate - the number of deaths per 1000 people per year |
| What is the impact of these influences on Population (3 points) | 1) Population will grow when the birth rate and immigration exceed the mortality and emigration rate 2) The population will decline if the death rate and emigration rate exceed the birth rate and immigration rate 3) The population will remain stable when the birth and immigration is approximately equal to the death and emigration rate |
| How is the growth of the population regulated | If a few individuals enter an unoccupied area with no shortage of food or other resources, and no predators, the number of individuals will increase exponentially |
| What is environmental resistance | It is the total number of factors that stop a population from reproducing at its maximum rate. Therefore a balance is reached which is called carrying capacity |
| What is carrying capacity | It is the balance that is reached when a population is at its maximum rate |
| What is limiting factors | They are the factors that help to regulate the growth of a population |
| What are the types of limiting factors (2 points) | 1) Density independent factors - physical factors eg Rainfall and catastrophic events eg floods 2) Density dependent factors - when organisms are more crowded there is more competition eg competition for food or oxygen, they are more easily found by predators, and spread diseases faster |
| What is a stable population | Is one which the numbers decrease when the size exceeds the carrying capacity. Therefore, it fluctuates around around the carrying capacity |
| What is an unstable population | It develops when the population exceeds the carrying capacity. This results in a habitat destruction and in the future, lowers the carrying capacity and not being able to support the animals in the environment |
| Draw and label the logistic and geometric graph for carrying capacity |
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| Why do the graphs not start at zero | Because there cant be zero animals in a population |
| How is a population estimated (3 points) | 1) Direct method - which can only be used for slow moving or stationary animals/plants 2) Indirect method - the quadrant method which is n=number in sample X size of whole habitat/ size of quadrant. This method involves choosing random quadrants and counting the number of the population in each random quadrant 3) Mark Recapture - this method involves taking a sample size marking them, releasing them, recapturing them in one area. (Estimated Population = Total number of marked animals x total number of animals in a second sample) /divided by the total number of marked animals in the second sample |
| What is direct method | Is the count of animals and plants and can only be used for slow moving or stationary animals/plants - |
| What is indirect method | It is the quadrant method which is n=number in sample X size of whole habitat/ size of quadrant. This method involves choosing random quadrants and counting the number of the population in each random quadrant |
| What is mark recapture | This method involves taking a sample size, marking them, releasing them, recapturing them in one area. (Estimated Population = Total number of marked animals x total number of animals in a second sample) /divided by the total number of marked animals in the second sample (P=MxC)/R |
| What is a predatory- prey relationship | It is a limiting factor in the population. Predation is a biological interaction where the predator kills the prey. |
| Why is there a predator-prey relationship (4 points) | 1) Regulates the abundance and distribution of the prey population 2) Increase biodiversity of the community preventing a single species becoming dominant 3) It keeps the prey population genetically fit by removing the sick and injured animals 4) Provides vital food for scavengers |
| What is competition | It is when 2 or more individuals of the same species compete for the same resource that there is a short supply of |
| What is intraspecific competition | It occurs between individuals of the same species and this is the most intense as it is generally in the same area for the same resource |
| What is interspecific competition | It occurs between individuals of different species where the niches in the habitat are very similar |
| Why are ecological niches important (4 points) | For a population to survive, its individuals must survive and reproduce. To do this they must: 1) Tolerate the physical environment e.g Temperature and PH 2) Obtain energy and nutrients 3) Cope with competition 4) Avoid predators |
| Define Ecological Niches | All the conditions necessary for an organism to survive and reproduce |
| What is competitive exclusion | Occurs when one of the two competing species is much more successful than the other - the one species survives and the other has a possibility of extinction |
| What is competitive co-existence | This occurs when two competing species co-exist in the same habitat although they have overlapping niches. They therefore compete for the same resources but are able to co-exist because their resources are slightly different |
| What is resource partitioning | Is the evolutionary process whereby species with similar requirements living in the same habitat, evolve specialized traits that enable them to utilize the resources differently thereby creating different niches to reduce competition |
| How can resources be partitioned (3 points) | 1) Different times - eg lion feeds at day, where a leopard feeds at night 2) Different parts of the habitat - eg depths of a lake 3) Different parts of the same plant - eg the giraffe eating the top leaves of a tree, and a kudu eating the bottom leaves |
| What is ecological succession | Is a predicable pattern of a gradual change over time in the types of species |
| What are the types of succession (2 points) | 1) Primary - begins on sites that have not had plants growing eg bare rock 2) Secondary - begins in areas where a disturbance removes some or all species but soil remains eg forest fire |
| What are disturbances (3 points) | 1) There are physical disasters eg storms, floods and fires 2) Humans or animals eg abandoned crop field, overgrazing or logged forests 3) Climate change |
| What are the stages of succession (3 points) | 1) Pioneer species 2) Intermediate species 3) Climax communities - it is the last stage, but is semi stable because the environment is not static |
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