RNR chap 3 study guide pt 1
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: the science of relationships between living organisms and their environments.
How do we classify organisms?
Species: similar by genetic make-up, could breed together
Populations: groups within a species that actually do breed together, although they are not exactly alike genetically
Genetic diversity: populations – they are not exactly alike genetically
Communities: many populations that live together in a habitat
Habitat: place or type of place where an organism or population of organisms lives
A ______ is a group of individuals within a species that live together and exchange genetic material; it is different from a species. For example, cottontail rabbits in Australia may be the same species as cottontail rabbits in the U.S., but they are very different populations. Individuals
within populations vary because of _____ _____ and the constant recombination of genes as each successive generation mates.
population, genetic diversity
All populations live in a ____, which provides resources such as food, water, proper environmental conditions, and cover from predators.
A _____ is a group of populations living in a particular habitat. They may be similar populations (e.g., birds in a forest), but the community will also include very dissimilar organisms (insects, fungi, mammals that also live in the forest).
An ____ is a community and its environment (biotic and abiotic); they can be small or large, and many are not distinct, they grade into each other to produce habitats known as ecotones.
Earth’s life-support systems consist of the ____ (where life is found), the atmosphere (the ____ with its greenhouse gasses and the _____
with its ozone layer are the most important to us), the _____(water as ice, liquid, or vapor), and the _____, the Earth’s core, mantle, and crust.
biosphere, troposphere stratosphere hydrosphere geosphere
Terrestrial ecosystems are divided into ____, large land areas with distinctive climate and resident biotic communities. These can be visualized in Figure 3-7, which shows several biomes that differ primarily in temperature and rainfall. Aquatic ecosystems are divided into___ ____ ____, which are analogous to biomes, and differ in characteristics such as depth, salinity, and water velocity.
biomes, aquatic life zones
Besides gravity, life on earth depends on the ____ ____ ____ ____ and the recycling of nutrients; these are physical laws that govern all ecosystems, and yet we can influence these laws and how ecosystems function by our activities - part of becoming more of a sustainable society depends on understanding these processes and protecting them.
one-way flow of energy
____ ____ in the form of electromagnetic waves (visible, ultraviolet, and infrared radiation) is absorbed by the atmosphere and biosphere, or is reflected back into space; remember ozone is a critical player in this process, without blocking UV radiation, life would not exist on Earth as it does.
After reaching the planet, most of the 1% of incoming radiation is re-radiated as longer-wavelength infrared radiation back into the atmosphere, where it encounters water vapor, carbon dioxide, methane, nitrous oxide and ozone - known as ____ ____The greenhouse effect allows life on the planet to exist, without it, average temperatures would be well below zero
human activities are altering the concentration of greenhouse gasses in the atmosphere, particularly ____, _____, and nitrous oxide, and the bulk of scientific evidence indicates we are increasing global temperatures, with potentially serious consequences.
All organisms in living ecosystems have a ____ ____ ____, outside of which they can not survive. This range is affected by all environmental factors affecting an organism, some of which are limiting factors.
range of tolerance
The _____ ____ _____ states that too much or too little of an abiotic factor can limit population growth, even if all other factors are unlimited. I woula amend this to add biotic factors in some circumstances, like the fish-mussel example I gave in class.
principle of limiting factors
All organisms in ecosystems are arranged into trophic webs, which are composed of
several trophic levels. _____ (autotrophic organisms) can make their own food, and the most important group of organisms in most ecosystems that can do this use photosynthesis, where they take CO2 and water and make oxygen and a carbohydrate (sugar)
All other organisms are _______, i.e., they must consume food to survive. In this group we have herbivores, carnivores, omnivores, saprovores (decomposing bacteria and fungi) and detritivores (animals that consume dead organic matter). Organisms feeding on the next trophic level down use this stored energy in aerobic respiration in their cells, converting the organic compounds back to CO2 and water. Many decomposers can do this in the absence of oxygen (anaerobic respiration), producing other end products such as hydrogen sulfide and ethyl alcohol (of particular importance to you beer and wine drinkers).
The energy all organisms need to survive flows in one direction through the trophic web, from plants through top carnivores and saprovores or detritivores. The important point, illustrated in Figures 3-13 and 3-15, is that...
at each transformation, energy is lost as heat, hence there is a maximum number of trophic levels that we see in nature - this is dictated by the inefficiency of energy transfer between trophic levels - 10% is often used as an estimate, hence 90% of the energy is lost as we go from one trophic level to another (low ecological efficiency).
explain effects of low ecological efficiency
This inefficiency means that we can support more people if we feed on autotrophs than if we feed on heterotrophs - many people on Earth do this already, they can’t really afford to waste energy on raising herbivores.
Primary production at the bottom of the trophic web can be divided into gross primary production (GPP) and ____ ___ ____, the
latter of which subtracts the rate of plant respiration from the rate of primary production. As you can see from figure 3-16, NPP rates differ widely among ecosystems, but swamps and marshes, tropical rain forests, and estuaries are particularly productive.
net primary production (NPP)
In contrast to the one-way flow of energy, nutrients recycle in ecosystems, which allows these systems to persist. All nutrients move through the planet’s biosphere, atmosphere, hydrosphere, and geosphere_____ _____. In these cycles, nutrients and water are transformed, stored, used, and released over and over in the world’s trophic webs.
The _____ cycle deals with movement and storage of water across the planet, including evaporation, precipitation, transpiration, runoff, and storage as ice
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