AP Biology Units Midterm!!

• atoms


  small units of matter that are composed of protons, neutrons, and electrons
• most of the mass is concentrated at the center of the atom in the nucleus
• control group


  a group in the experiment in which a variable is not being tested
• experimental groups 


  the group that receives the variable being tested in the experiment
• independent variable 


  the variable that is manipulated by the researcher to see how it affects the dependent variable

  • x axis of a graph
  • does not respond to the other variable
• dependent variable


  the variable that is measured in an experiment

  • y-axis
  • responds to the independent variable
• D.R.Y. M.I.X.

  Dependent variable

  Responding variable

  Y-axis

  Manipulated variable

  Independent variable

  X-axis
• modern cell theory

  • the cell is the smallest living unit in all organisms
  • all living things are made of cells
  • all cells come from other pre-existing cells
• unicellular


  (of protozoans, certain algae, spores, etc.) consisting of a single cell
• multicellular


  (of an organism or part) having or consisting of many cells.

  • these can then be arranged into tissues which can make up organs that can be part of an organ system (also known as the biological levels of organization)
• maintaining homeostasis

  • ex. enzymes will use a certain pH range to work correctly
  • can mean maintaining a certain temperature and a certain percentage of water concentration
• feedback systems help with maintaining homeostasis
• single-celled organisms, like amoeba, rely on their cell membrane to maintain homeostasis internally
• chemical reactions happening in living organisms are part of metabolism
• plants are autotrophs and can capture light energy to make glucose in a process known as photosynthesis
• animals are heterotrophs that typically need to eat and digest in order to obtain glucose
• both plants and animals break down glucose in cellular respiration to make atp energy
• living organisms have genetic material that code for their development and growth
• internal stimuli 


  stimuli that originate within the body, such as hormones and nerve impulses
• external stimuli 


  sensory stimuli that are detected by the sensory receptors
• plants respond to stimuli by growing in the direction in which the source of the light is coming from
• the gene frequencies in a population of living organisms can change over time due to mechanisms such as mutation, natural selection, and genetic drift
• some genes can code for certain traits that result in higher reproductive fitness, these are called adaptive traits.
• some genes may code for traits that lower reproductive fitness, but are beneficial to the individual.
• biological levels of organization

  cell -> tissue -> organ -> organ system -> organism -> population -> community -> ecosystem -> biome -> biosphere
• when you have a lot of cells that work together for a combined function you end up progressing from the cell, to the next level, tissues
• tissues make up organs
• when you have multiple organs working together in a body, you end up with an organ system
• by tying in all of the organ systems, you produce and individual organism that is more complex and more efficient
• when you put multiple organisms together, you create a population
• including other populations along with the population of the original organism's population and you create a community
• a community includes many populations, but it does not include abiotic factors.
• abiotic factors are non-living factors that affect the environment and living organisms
• biotic factors are the living things in an ecosystem that can affect the population of organisms
• when abiotic factors are considered, and the biotic factors are also considered, they create an ecosystem
• as different ecosystems can be found in different regions all over the world, when talking collectively, we reach the biome level
• ecosystems refer to one singular area, biomes consider all of the areas this ecosystem can be present
• when all of these biomes are put together, they create the biosphere
• the biosphere includes anywhere on the planet where life is supported
• water is a polar molecule, meaning it has a positive and negative end