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Semester Exam - Bio

Biology Semester Exam - Index Cards

Term - QuestionsDefinition - Answer
Observation usually leads into developing a question or problem answered by scientific investigation; is often research based
Question or Problem a statement that addresses the observation of the investigator which is written in question format
Hypothesis an educated guess or a statement of explanation that must be testable and stated using an If.....then format
Prediction a logical statement of the expected outcome of an experiment assuming that the hypothesis is supported
Variable a factor capable of change in scientific experimentation
Independent variable the factor that is changed or tested in an experiment
Dependent variable the factor that is measured in an experiment or the responding variable
Controlled variable the experimental "constants" that must remain the same in an experiment.
Experiment a test designed to support or reject a hypothesis by pinpointing a cause-and-effect relationship. Most experiments in science are controlled experiments that have two groups and follow a set procedure or step by step instructions.
Control group the group that does not get special treatment; represents the norm for comparison of experimental results
Experimental group the group that receives the independent variable or special treatment
Results/ Data the numerical information collected about what happened in an experiment is organized or graphs so that analysis can lead to forming a conclusion
Mean the average score; total sum of scores added and divided by the number of scores
Median the middle score or the two middle scores divided by two
Mode the most frequently occurring score
Conclusion a statement of analysis (data-based) that usually supports ( a hypothesis can not be "proven) or rejects a hypothesis
Communication/ Report Results scientists share their research findings on a global basis using computer technology or in scientific journals
Theory an explanation that has been extensively tested and verified many times with peer reviews - can be subject to change but are usually not
Law a scientific principle that appears to be without exception and not subject to change.
Atoms the building blocks of matter
Atoms Central Nucleus contains most o the atom's mass
Central Nucleus contains: protons; positively charged; neutrons; no charge
Electrons negatively charged; found in orbital (or energy levels or shells) outside the nucleus
Uncharged Atom the number of protons equals the number of electrons
Element substance composed of only one type of atom
Periodic Table of the Elements organizes all of the elements based on their number of protons, and their chemical properties
Element Symbol each element is represented by a one or two letter chemical symbol
Isotope extra neutrons in the nucleus
Charged atoms or ions atoms that gain or lost electrons
Negative ions atoms that gain electorns
Positive ions lose electrons
Elements pure substances made of only one kind of atom
Period on Periodic table corresponds with the filling of each energy level
Group on Periodic table corresponds with the number of electrons in the outermost energy level
Combination of atoms atoms combine in definite proportions or rations according to the oxidation or valence number
Combination of atoms tell what the combining ability of a given atoms is
Identification of Valence Number The best way to tell an atom's valence number is to look at the group number it is in - all atoms of elements in the same group will have the same number of electrons in the outermost energy level or valence shell
Compounds forms when different atoms join to form molecule of a new substances in a definite ratio, which is expressed by a molecular formula
Molecular Formula tells how many total atoms are found in a molecule
Forming of Molecules can be made of the same type of atoms joined together as paired unit such as diatomic element such as hydrogen or oxygen
When compounds do form the atoms usually combine by: sharing electrons or transferring electrons
Ionic Bonds these bonds are strong bonds made when atoms transfer electrons between the valence shellss
Covalent Bonds these are relatively strong bonds made when atoms share electrons in their valence shells.
Hydrogen Bonds are very "weak" bonds. Water molecules are held together by these bonds. DNA's bases are held by these temporary bonds
Water the most important compound in your body. Over 70% of the human body is made of water. Cells depend on water to make important biochemical reactions happen for them
Properties of Water (1) water stores or loses heat slowly. (2) Cohesion and adhesion allows water to bond to itself and different substances. (3) Water is formed from a polar covalent bond. (4) Water has high surface tension. (5) Water can form weak hydrogen bonds.
Cohesion allows water molecules to stick together and form round water droplets. Trees move water against gravity to leaves far about grounded by cohesion and capillary action
Adhesion allows water to be attracted to many other polar compounds with charged ends.
Polar covalent bond The water molecule has partially charged ends because of the electrons are not shared equally. Polarity makes water the universal solvent for making many important solutions in body when the solute or substance dissolved is another polar or ionic molecule
High Surface Tension a measure of how difficult it is to break the surface of liquid
pH the percentage of hydronium ions in a given solution
pH - Describes whether a substance is acid, neutral, or base. Each pH value is different by a power of ten not one.
Acid are solutions with a greater number H+ ions than -OH ions (hydroxide ions). The pH value is under 7
Acid Examples lemon juice, vinegar
Base solutions with a greater number of -OH ions than H+ ions. The pH value is over 7
Base examples solutions with a greater number of -OH ions than H
Neutral Solutions equal numbers of H+ and -OH and have a pH value of 7
Neutral Solution Example Water, Alcohol
Buffers weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH
Created by: willitre2020



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