Último Examen Flashcards
What is an habitat?
The place where a particular population of a species lives.
What is a community?
The many different species that live together in a habitat.
Of what consists an ecosystem?
Consists of a community and all the physical aspects of its habitat, such as soil, water and weather.
What are the abiotic factors?
The physical aspects of a habitat.
What are the biotic factors?
The organisms in a habitat.
What components of an ecosystem are NOT part of a community?
The abiotic factors, like soil and other non-living things.
From what words comes the name “Ecology”, and what they mean?
Oikos= "house" or "place where on lives" Logos= "study of" Ecology= "study of habitats"
What is biodiversity?
The variety of organisms, their genetic differences, and the communities and ecosystems in which they occur.
What is ecology?
The study of interactions of living organisms with one another and with their physical environment.
What is called primary productivity?
The rate at which organic material is produced by photosynthetic organisms in an ecosystem. This determines the amount of energy available in an ecosystem.
Which organisms are the producers?
The ones that first capture energy, like plants, some types of bacteria and algae.
Which organisms are the consumers?
The ones that consume plants or other organisms to obtain the energy necessary to build their molecules.
What is called a food chain?
The path of energy through the tropic levels of an ecosystem.
What organisms occupy the first tropic level?
The producers that get their energy from the sun.
What animals occupy the second tropic level?
The herbivores, animals that eat plants or other primary producers. These are the primary consumers.
What animals occupy the third trophic level?
The secondary consumers, animals that eats other animals. These may be carnivores or omnivores.
What are detritivores? Which organisms are known as decomposers?
Organisms that obtain their energy from the organic wastes and dead bodies that are produced at all trophic levels.
Bacteria and fungi, because they cause decay.
Of what is composed the fourth trophic level?
Of those carnivores that consume other carnivores. They are called tertiary consumers, or too carnivores.
What is called a food web?
A group of interconnected food chains.
What is an energy pyramid?
A diagram in which each trophic level is represented by a block, and the blocks are stacked on top of one another, with the lowest trophic level at the bottom.
What is the amount of energy passed from one trophic level to another?
It’s a tenth of the energy. So from the energy producers have, primary consumers only get 1/10 of it. From the energy of the primary consumer the second only get 1/10, making it 1/100 of the original energy of the producer.
What is biomass?
The dry weight of tissue and other organic matter found in a specific ecosystem.
How producers differ from consumers?
Producers get their energy from the sun, the consumers get their energy from the producers, making it a cycle that goes sun->producers->consumers
What are the four trophic levels?
First: producers
Second: primary consumers, herbivores
Third: secondary consumers, omnivores or carnivores
Fourth: tertiary consumers, carnivores that eat carnivores
The main reason of why food chains do NOT tend to exceed four links?
Because the amount of energy decreases in a 90% each level, so the energy that receives the fourth trophic level is too low in order to be able to maintain a fifth level.
What is a biogeochemical cycle?
The path of cycles, that consists when a substance enters living organism, the time it stays in it, and when it return to the non living environment.
Mention the steps of the water cycle.
Evaporation and transpiration -> water vapor (clouds)
Precipitation-> rivers
Runoff(when it goes through a river)-> lake or ocean
Percolation into soil-> groundwater
Transpiration=evaporation of water from leaves after passing through the plant.
Mention the steps of the carbon cycle.
Respiration: carbon dioxide is formed
Combustion: Carbon is released to the atmosphere through burning
Erosion: organisms in water create calcium carbonate shells, that after being eroded the carbon becomes available to other organism.
Mention the steps of phosphorus cycle.
Phosphorus is in rocks and soil as calcium phosphate
It dissolves in water and is absorbed by the roots of plants
Animals eat plants and reuse organic phosphorus
The animal dies, and the phosphorus return to soil and rock
Mention the steps of nitrogen cycle.
Assimilation: absorption and incorporation of nitrogen into organic compounds by plants
Ammonification: production of ammonia by bacteria during decay of organic matter
Nitrification: production of nitrate from ammonia
Denitrification: is the conversion of nitrate to nitrogen gas
Why is Costa Rica such a biodiverse country? How much of the world’s biodiversity it has?
Because there are many different species in little amount space.
It is about the 5% of the world diversity.
What is coevolution?
Back-and-forth evolutionary adjustments between interacting members of a community.
What is predation?
The act of one organism killing another for food.
What happens in parasitism?
One organism feeds on and usually lives on or in another organism.
What are secondary compounds?
Defensive chemicals of plants in order to defend predation.
What is symbiosis?
Two or more species live together in a close, long-term association
Mention and describe the four types of symbiosis.
Parasitism: the parasite benefits, the host gets affected +/-
Mutualism: both organisms benefit +/+
Commensalism: one benefits and the other is neither harmed nor helped +/o
Ammensalism: one doesn’t get affected and the other gets “perjudicado” -/o
What is competition?
When two species use the same resource
What is called a niche?
The functional role of a particular species of an ecosystem.
What is a fundamental niche?
The entire range of resource an organism is potentially able to occupy within an ecosystem.
What is a realized niche?
The part of its fundamental niche that a species occupies.
What is competitive exclusion?
The elimination of a competing species, happens when two species that are competing, the one that uses the resources more efficiently will eliminate the other.
What is biodiversity?
The variety of living organisms present in a community.
What causes acid rain?
Sulfur introduced into the atmosphere by smokestacks, combine with water vapor, and when it rains the water has a ph of 4, when it should be 7.
What is the major cause of the ozone destruction?
Chemicals called chlorofluorocarbons, or CFCs
What is the main contribution of the global warming?
Human activity in modern times.
What is the cause of the greenhouse effect?
The increased levels of greenhouse gases, such as carbon dioxide which is increasing because of the burning of fossil fuels, the deforestation, and the urban industrialization; also increased methane levels because the excess of cows.
What happens in the process called biological magnification?
DDT is concentrated in the environment and in fatty tissue of animals. When other animals consume these, the levels of DDT increase. The presence of DDT in birds could cause the egg to break because it is too thin, or malformation like the beak being each time lower. It causes a lot of death in birds.
Mention and describe three loss of resources that can’t be replaced.
Extinction of species, that could have DNA information to cure diseases, but as they extinct, it is impossible to recuperate the info
Loss of topsoil, it is being lost because of animals overgraze pastures, and the practice of poor land management.
Groundwater pollution and depletion, gw is stored in aquifers, and the level of these are not enough to compensate the use of water by humans
Two harmful effects of acid rain?
It affects the forests, harming the trees and killing the symbiotic fungi in their roots
It contaminates the lake and killing what lives in them.
