domingo, 18 de septiembre de 2011

Biology Notes - Chapter 2: Natural history and differences between autotrophs, heterotrophs and others

Chapter 2
Section 1
Biotic are alive organisms, while abiotic are not alive factors (light, water, temperature). What affects the environment (pollution) also affects you, so you should be conscious. Natural history is the study of plants and animals, including where they grow and live, what they eat, or what eats them.
Oikos means home in Greek. So this is the root for the word ecology, which is the study of interactions that take place between organisms and their environment. Ecology is a root of biology that uses a lot of quantitative or descriptive data.
The biosphere is the portion of Earth that supports living things. Even though it is thin, it supports a diverse group of organisms in a wide range of climates. Living things depend on living factors, but also on nonliving factors. 
The nonliving parts of an organism parts of an organism’s environment are the abiotic factors. They include air, currents, water, temperature, moisture, light, soil, depth (pressure), salinity, etc. Biotic factors are all the living organisms that inhabit an environment.
An organism is an individual living thing that has the characteristics of life + energy. A population is a group of organisms, all of the same species, which interbreed and live in the same area at the same time. Members of the same population may compete with each other for food, water, mates, or other resources. Competition can occur whether resources are in short supply or not. A biological community is made up of interacting populations in a certain area at a certain time. An ecosystem is made up of interacting populations in a biological community and the community’s abiotic factors.
A habitat is the PLACE were the organism lives. Habitats can change and disappear due to natural or human reasons. The niche is the role or position a species has in its environment and how it meets its needs for food and shelter, how and where it survives and where it reproduces in its environment. Two species with the same niches can’t live in the same community.
The relationship in which there is a close and permanent association between organisms of different species is called symbiosis. Symbiosis means living together; three kinds of symbiosis exist: mutualism (+/+), commensalism (+/o), and parasitism (+/-).
All organisms are either consumers or producers. Predators are consumers. Producers live either by photosynthesis (inorganic - light) or chemosynthesis (chemicals).
Section 2
The producers: autotrophs. Auto means self and troph means energy. Plants use the sun’s energy to manufacture food through photosynthesis. Organic compounds- living or once living things that contain carbon. Autotrophs produce organic compounds from inorganic energy. Photosynthesis (light, produce), Chemosynthesis. Other organisms depend on autotrophs; these are called heterotroph (other, energy), which are organims that can’t produce its own food. Apart from herbivore, omnivore and carnivore, scavengers eat animals that have already died, and decomposers break down the complex compounds of dead and decaying plants and animals into simpler molecules that can be easily absorbed. 
A food chain is a simple model that scientists use to show how matter and energy move through an ecosystem. Nutrients and energy move from autotrophs to herotrophs and eventually to decomposers. Arrows are used to show the order. Most food chains consist of two, three or four transfers. The less steps the more energy that is transferred to the top step. We call each organism a feeding step or trophic level. A food web shows all the possible feeding relationships at each trophic level in a community. Biomass is the total weight of living matter at each trophic level. A pyramid of biomass represents the total weight of living material available at each trophic level.
Carbon Cycle. Carbon is the building block of the molecules of life.
Nitrogen Cycle: ---
Phosphorous cycle: element that is never a gas
Water cycle: ---
Fixing is to take an inorganic element an incorporate it to the organism

To see the answers to the homework of this section, click here.

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