7 Characteristics of Life

• Life has levels of organization

7 Characteristics of Life

• Order is a key characteristic
• Reproduction is essential for life
• Growth and Development happen in all lifeforms
• Energy Processing is required
• Response to the environment is an important characteristic
• Regulation must occur within the organism
• Evolutionary Adaptation develops over time

Functions of Life

• All living organisms are composed of one or more cells
• Cells are capable of carrying out life functions
• Organelles in single-celled organisms act like tissues and systems in multicellular organisms
• Single-celled organisms use specialized cell organelles to maintain homeostasis
• Metabolism is the web of enzyme-catalyzed reactions in a cell or organism, such as respiration
• Response is how living things interact with their environment
• Homeostasis is the maintenance and regulation of internal cell conditions like temperature and water
• Growth is when living things change size/shape
• Reproduction is when living things produce offspring sexually or asexually
• Excretion is the removal of metabolic waste
• Nutrition is feeding by photosynthesis or absorption of organic molecules

3 Levels of Organization in Life

• Chemical Level
• Biological Level
• Ecological Level

Chemical Organization Level

• Atoms are the smallest unit of matter
  • They are classified as elements
  • They are composed of subatomic particles: protons, neutrons, and electrons
• Molecules are two or more atoms chemically joined
• Organic Macromolecules are complex molecules
  • They are made of C, O, H, and/or N
  • They are divided into categories: carbohydrates, lipids, proteins, and nucleic acids
• Cellular Organelles are structures of the cell
  • They are made of organic macromolecules
  • They perform specific functions of life

Biological Organization Level

• Cells are the basic structural and functional unit of life
  • Prokaryotes and Eukaryotes are the two basic cell types
• Cells contain 3 basic structures:
  • Nucleic Acids
  • Plasma Membrane
  • Cytoplasm
• Tissues: A group of cells with a common structure and function
  • Animals have four tissue types: connective, muscle, nervous and epithelial
  • Plants have three: vascular, ground and epidermal
• Animal Tissues
  • Connective tissue connects or separates groups of other tissues
    • It is found in between all the other tissues and organs in the body
    • Most connective tissue also contains fibers, which are long, narrow proteins
  • Muscle Tissue comprises all muscles in the body
    • Allows muscles to contract
    • There are three types: skeletal, cardiac, and smooth
  • Nervous tissue is found in the brain, spinal cord, and peripheral nerves
    • It is made up of neurons and neuroglia
    • These cells help nerve impulses travel
  • Epithelial tissue covers the surfaces of organs like the skin, trachea, reproductive tract and the digestive tract's inner lining
    • It creates a barrier that helps protect organs
    • It absorbs water and nutrients
    • It gets rid of waste
    • It secretes enzymes or hormones
• Plant Tissues
  • Vascular tissue transports substances throughout the different parts of the plant
    • Two types: xylem and phloem
    • Xylem transports water and soluble nutrients
    • Phloem transports organic compounds used as food
  • Epidermal tissue makes up a single layer of cells
    • It covers a plant's roots, stems, leaves, and flowers
    • It guards the plant against water loss
    • It regulates the exchange of CO2 and O2
    • It absorbs water and nutrients from the soil
  • Ground tissue all cells that are not vascular or dermal
    • There are three types: parenchyma, collenchyma, and sclerenchyma
• Organs are self-contained group of tissues that performs a specific function
  • The human body has 78 different organs, the skin is the largest
  • Vital organs are necessary for survival
  • Humans have five: brain, heart, liver, kidneys, and lungs
• Organ Systems are the highest level of an organism's bodily organization
  • They are made up of groups of organs that work together, in order to carry out a certain function
  • Example: The digestive system includes the esophagus, stomach, small intestine, and large intestine
    • All of these organs play a role in the digestion of food
• An Organism is a single individual, or being
  • Complex individuals contain organ systems
  • Simple contain only an information molecule

Ecological Organization Level

• Species is a group of organisms that share the same traits
  • They can reproduce with one another in nature and produce fertile offspring
• Population is the number of organisms of the same species
  • They live in a particular geographic area at the same time
  • They have the capability of interbreeding
  • For interbreeding to occur, individuals must be able to mate with any other member of a population and produce fertile offspring
  • Populations contain genetic variation within themselves, and not all individuals are equally able to survive and reproduce
• Community is a group of populations that live together
  • They interact with each other within an environment or habitat
  • Communities partake in direct and indirect biotic interactions
    • E.g., predator-prey, herbivory, parasitism, competition and mutualisms
• Each organism within a community can be categorized within a specific trophic level
  • Primary producers (autotrophs) manufacture their own food
    • They use energy from the sun to perform photosynthesis.
    • E.g., green plants and algae
  • Consumers or heterotrophs must obtain their nutrition from other organisms
    • Primary consumers (herbivores) eat the plant material
    • Secondary and tertiary consumers (carnivores / omnivores) eat the primary consumers
  • Decomposers (heterotrophs) consume dead plant and animal material
    • They recycle the nutrients back into the earth
• Ecosystems describe a single environment
  • They include every living (biotic) organism and non-living (abiotic) factor that is contained within it or characterizes it
  • The contents can range from light and moisture levels to plant and animal life
    • Processes range from birth and reproduction to death and composition
• Biotic factors are living organisms
  • They are grouped into producers, consumers, and decomposers
• Abiotic factors are non-living components
  • They can be climatic, social, and edaphic (soil type)
  • Without abiotic factors, no ecosystem can provide for biotic factors
• Biomes are areas classified according to the species
  • Species live in that location
  • Temperature range, soil type, and the amount of light and water are unique to a particular place
    • They form the niches for specific species allowing scientists to define the biome
  • Some count six, others eight, and still others are more specific and count as many as 11
• Biosphere are the regions of the surface, atmosphere, and hydrosphere of the earth
  • They are occupied by living organisms