Characteristics of Life • Made of cells • Able to reproduce • Contains DNA • Grows and develops • Uses materials and energy • Respond to their environment
Levels of Organization • Cells • Tissues • Organs • Organ systems • Organisms • Population • Community • Ecosystem • Biosphere
Getting Food • Autotrophs are organisms that can capture sunlight or energy to produce their own food. Also called producers. • Examples are plants, some algae, and some bacteria.
Getting Food • Heterotrophs are organisms that rely on other organisms for their energy and food supply. Also called consumers.
Types of Heterotrophs • Herbivores obtain energy by eating only plants. Examples: cows, horses • Carnivores eat animals. Examples: snakes, owls • Omnivores eat both plants and animals. Examples: humans, bears • Detritivores feed on plant and animal remains and other dead matter. Example: snails, earthworms
Types of Heterotrophs • Decomposers break down organic materials. • Examples are fungi and bacteria.
Food Chains and Webs • A food chain is a series of steps in which organisms transfer energy by eating and being eaten. • A food web is a network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem.
Ecological Pyramids • Ecological pyramids are used to show trophic levels in an ecosystem.
Energy Pyramid • An energy pyramid shows the relative amount of energy available at each trophic level. • Organisms use about 10% of this energy for life processes. • The rest is lost as heat.
Biomass Pyramid • Biomass is the total mass of living organisms in a given area or ecosystem. • In a biomass pyramid, the greatest amount of biomass is at the base of the pyramid.
Pyramid of Numbers • A pyramid of numbers shows the relative number of individual organisms at each trophic level.
Cycles in Nature • The water cycle is the process in which water moves between Earth’s surface and the atmosphere. • Water is returned to the atmosphere through evaporation and transpiration (plants).
Cycles in Nature • Carbon and oxygen are cycled through photosynthesis and respiration.
Cycles in Nature • The nitrogen cycle is necessary for organisms to make amino acids and proteins.
Interactions Among Organisms • Competition occurs when organisms attempt to use a resource in the same place at the same time. • Predation is an interaction in which one organism (predator) captures and feeds on another organism (prey).
Interactions Among Organisms • Symbiosis is a relationship in which two species live closely together. • Mutualism is a relationship in which both species benefit. Ex: flower/insect • Commensalism is a relationship in which one species benefits and the other is not affected.
Interactions Among Organisms • Parasitism occurs when one organism (parasite) lives on or inside another organism (host).
Ecological Succession • A series of predictable changes that occurs in a community over time.
Two Types of Succession • Primary succession takes place on an area that is originally completely empty of life.
Example of Primary Succession • In an area covered by lava, the first plants will be mosses that grow in cracks in the rock. • When they die, they will decompose and begin to form soil which will support grasses. • Eventually enough soil is formed to support small trees.
Two Types of Succession • Secondary succession occurs in an area where life once existed but has since been destroyed. • For example, a forest that has been destroyed by a wildfire will contain no life. The first plants to grow will be weeds, followed by shrubs, pine trees, and hardwoods.
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Environmental Problems • Extinction occurs when a species disappears from all or part of its range.
Environmental Problems • Endangeredspecies are species whose population size is declining in a way that places it in danger of extinction.
Environmental Problems • Pollution is any potentially harmful substance added to an ecosystem.
Environmental Problems • Global warming is an increase in Earth’s average temperature caused by human activities adding carbon dioxide and other gases, such as methane, to the atmosphere.
Everything You Ever Wanted to Know About Cells And Some You Didn’t.
Two Types of Cells • Prokaryotes are simple cells that do NOT have a nucleus or organelles. Ex: bacteria • Eukaryotes are cells that have a nucleus and organelles. Ex: plant and animal cells
ORGANELLES • An organelle is a structure within the cell with a specialized function.
Types of Organelles • 1. nucleus- contains DNA and regulates cell activities • 2. mitochondria- supplies the cell with energy through cellular respiration • 3. ribosomes- produce proteins • 4. Golgiapparatus (body)- processes and packages proteins for export