Pre-AP Biology: Unit 2 Ecology Review Outline

Transcription

1 LT 2.1 Characteristics of Life Pre-AP Biology: Unit 2 Ecology Review Outline There are seven characteristics of life. 1. All living things are made of one or more cells. o Example: A bacteria is a unicellular living thing; A human is a multicellular living thing. 2. All living things must be able to grow. o Example: An acorn germinates to become a sapling, which then grows to become an Oak tree. 3. All living things must be able to reproduce. o Example: Some organisms reproduce sexually by two mating individuals (such as rabbits), while other reproduce asexually by creating an exact copy of themselves (such as bacteria) 4. All living things must be able to adapt. o Example: Organisms possess certain traits that make them better suited for their environment, such as a desert fox has large ears to allow it to cool off more easily. These traits are passed on from generation to generation so long as they continue to be advantageous. 5. All living things must respond to the environment. o Example: Sunflowers will lean toward their light source/the Sun in order to be in a better position to absorb light. 6. All living things have a metabolism (use energy). o Example: Animals are heterotrophs that consume other organisms to break down for energy, and then conduct cellular respiration on the cellular level. Plants are autotrophic and obtain energy via photosynthesis. 7. All living things must be able to maintain homeostasis. o Example: Maintenance of body temperature by sweating or shivering. Also - all living things use DNA as the genetic code for their structure and function (Universal Genetic Code). The living things in an environment make up the BIOTIC factors (plants, animals, fungi, and bacteria). The nonliving things in an environment make up the ABIOTIC factors (rock/soil, water, and climate). Viruses are nonliving. They do not possess all the characteristics of life. Viruses are unable to reproduce without a host and are passive (they do not actively respond to the environment, grow, maintain homeostasis or regulate their conditions independently). LT 2.2 Levels of Organization The levels of Ecological Organization describe the arrangement of biological organisms in relation to one another. At the simplest level of the hierarchy are individual organisms. Individual Organism The first level of the ecological hierarchy is the individual organism. This level of the hierarchy examines how one organism interacts with its environment. Aspects of evolution are used extensively in studying this level. For example, the individual-organism level allows a scientist to study why a giraffe has a very long neck. He can infer that evolution has given the giraffe the long neck so it can reach a food source high on a tree. Organismal ecology is concerned with the biological, morphological and physiological development of individual organisms in response to their natural environment. Populations The second level involves populations. A population contains a group of individuals -- belonging to one species and living in a specific geographic area -- which interact with one another. Population ecology studies the interactions among the individual members of a population.

2 Communities The third level of the ecological hierarchy describes communities of life. The community level focuses on the relationship between different species in a community. Predator and prey relationships play a large role in community-level analyses. Parasitism and competition between species are another important part of this ecological level. Ecosystems The next level up is an ecosystem. A community is part of an ecosystem, but does not comprise an entire ecosystem. Nonliving components in the environment are included in an ecosystem. The living organisms in an ecosystem interact with one another and with the nonliving factors in the environment. Examples of an ecosystem include a single lake, a confined forest, a prairie or a mountain summit. Biomes Biomes are groups of ecosystems that have common characteristics for the environment they exist in, based on their geographic location (latitude), climate, and plant-life. Examples of biomes include deserts, rainforests, temperate forests, and tundra. Biosphere At the widest level of organization, there is the biosphere which represents the totality of all things and habitable space on Earth, including all interactions. The biosphere includes all ecosystems on Earth and how they interact together. By default, the biosphere includes climate, geology, the oceans and human pollution. LT 2.3 Ecological Relationships All energy in all systems ultimately originates from the Sun. This is an abiotic factor that begins all food chains and food webs. Organisms use one of the following methods to obtain energy: o Autotroph: organism that is able to produce its own food through a chemical process such as photosynthesis o Heterotroph: organism that must consume other organisms to obtain energy o Saprotroph: organism that breaks down dead and decaying organic matter to obtain energy Then, organisms are further classified based on their feeding relationships with other organisms. o Producer: autotrophic organism that is the base of all ecosystems (phytoplankton, plants, etc.) o Consumer: heterotrophic organisms Primary (1st o ): herbivores Secondary (2nd o ): organisms that eat the herbivores Tertiary (3rd o ): organisms that eat the secondary consumers Higher Levels (4th o +): top tier predators; organisms that eat other predators o Decomposer: usually bacteria or fungi (mold, mushrooms, etc.) Movement of Energy o Food Chains are simple, lateral diagrams showing how energy moves through one part of an ecosystem. o Food Webs are complex, branching diagrams that explore many possible relationships between organisms and many interactions, since organisms tend to have more than one food source. This is more representative of how energy moves through an entire ecosystem. o Energy Pyramids show the relationship between the amount of energy in a particular trophic level and the number of organisms in that level or biomass (amount of mass) Producers represent the largest biomass in all ecosystems

3 Top predators/tertiary consumers/4 th degree+ consumers always represent the smallest biomass o The 10% Rule of Energy in Ecosystems: Energy is lost as it moves through the trophic levels. 90% of the energy from consumption is used up by an organism or lost to heat 10% of the energy is conserved within the body of the organism and available for use by the next trophic level when the organism is eaten LT 2.4 Ecological Succession Succession is progressive change in ecological conditions in an environment over time. o Primary Succession: ecological development and diversification in an area where no life previously existed (new island formed from a volcanic eruption; glacier melts and exposes rock) o Secondary Succession: ecological development and diversification in an area that was previously inhabited by plants and animals, but was disrupted and destroyed and new is developing anew (land previously cleared for farming is now growing back up undisturbed, a forest burns down in a fire then regrows) Pioneer Species are the organisms that first inhabit an area during succession. They pioneer the land and prepare it for other new species to arrive, most importantly by helping to create soils during primary succession. Pioneer species are most often: o Mosses: simple, nonvascular plant o Lichen: symbiotic relationship between a fungus and photosynthetic bacteria Climax Community o A climax community is an ecosystem in its peak condition, or in its mature state. Ecological succession is a series of steps that ultimately leads to the stable environment of a climax community.

4 o Characteristics include a diverse array of plants and animals, complex relationships/food webs including tertiary consumers, large mature plant life. o The climax community of Virginia is an Oak-Hickory Deciduous Forest. Example of Primary Succession: LT 2.5 Population Ecology Population growth can be exponential or logistic. o Exponential growth Birth rate is higher than the death rate Growth curve graph shows a positive slope (line going almost straight up) o Logistic growth Birth rate is higher than the death rate until carrying capacity is reached, at which point population growth stops, then the birth and death become equal or nearly equal. Growth curve graph shows a steady increase to a leveling off point Carrying capacity: maximum number of organisms an environment and its resources can support (indicated by where the line goes flat on a graph) Negative Population Growth o When a population s numbers decline, this is call negative population growth. o Death rate is higher than the birth rate o Indicated by a negative slope on a growth curve graph Population growth is influenced by limiting factors which affect how fast a population can grow o Density dependent factors depend on the population s density, or the number of organisms Predation Disease Availability of resources such as habitat and food

5 o Density independent factors are not influenced by a population s size, and have an impact regardless Deforestation or other habitat destruction Natural disasters that wipe out habitats such as floods and fires The Human Population is currently growing at an exponential rate, and has increased at a dramatically faster rate in the last century. o Exponential Growth is unsustainable and humans will eventually reach a global carrying capacity. Humans have increased the carrying capacity for our population through agriculture, technology, medicine, and sanitation. o Age Distribution Pyramids show how many individuals there are per each age group and gender. These show if a population is growing, experiencing no or little growth, or declining. LT 2.6 Interaction Among Organisms Organism in an environment interact by: o Competition for resources such as food and habitat o Predator-Prey Symbiosis is the relationship of shared between different species. o Mutualism: two organisms that have a relationship where both benefit (flowers are pollinated by bees; bees get nectar from the flowers for food) o Commensalism: two organisms that have a relationship where on species benefits, and the other is unaffected (a bird builds a small nest in the shelter of a large tree) o Parasitism: two organisms that have a relationship where on species benefits and the other is harmed (a tick on a dog) Human Impacts on Ecosystems o Negative: deforestation; overfishing; industrial farming; pollution in the water and air from commercial industry; poaching o Positive: designated protected areas; conservation awareness and education; legal protections for threatened and endangered species; reforestation; soil replacement and erosion prevention; regulation of pollutants

6 LT 2.7 Biogeochemical Cycles Nutrients cycle through the environment through living things. Many cycles involve the uptake of nutrients by plants, which are consumed through the food chain, and ultimately returned to the Earth to be recycled when the organisms die. Key cycles in biology are: o Water/Hydrologic Water moves from the Earth s surface and ground water to the atmosphere and back Steps: precipitation, condensation, evaporation, and transpiration Water is stored in oceans/lakes/rivers/etc., ice caps and snow, as well as ground water o Carbon All living things are made of carbon-based molecules Plants take in carbon dioxide from the air during photosynthesis and convert it into organic material that becomes part of the plant s tissues. Carbon sinks are where most of the world s carbon is stored. This includes the world s forests (stored in plants) as well as in fossil fuel reserves beneath the surface. o Oxygen Oxygen is a biproduct of photosynthesis. Plants produce oxygen and release it as waste and then this oxygen is taking in by animals for cellular respiration. o Nitrogen Most organisms can only use nitrogen in the form of nitrogen compounds, such as ammonium or nitrate In order for nitrogen to be utilized by plants and animals it must be converted from elemental nitrogen into these compounds. This is carried out by specialized bacteria. Nitrogen Fixation: Bacteria convert gaseous nitrogen into ammonia o Phosphorus Necessary for health plant development, which is key to the foundation of all ecosystems Artificially introduced phosphorus from fertilizers can have negative environmental impacts Algae Blooms: too much phosphorus washed into water ways causes algae to overgrow rapidly and then die off, resulting in low oxygen levels in the water which kills off other species