Exam 1 Questions Flashcards
- What is a hypothesis? Name 2 ways a hypothesis can be eliminated without testing. Are there any short comings to using these methods to eliminate a hypothesis?
Hypothesis: Tentative explanation for a pattern
A. Get rid of non-observable hypotheses
B. Get rid of hypotheses that are inconsistent of known knowledge
- What are the 6 basic steps in the science process?
- Observe a pattern
- Formulate hypotheses to explain the pattern
- Get rid of some hypothesis
- Determine the predictions of the remaining hypotheses
- Run experiments
- Evaluation of results
- Give 3 reasons why in a scientific investigation it is necessary to work with more than 1 hypothesis?
- To reduce researcher bias
- Increases the likelihood that you will find the factor causing the pattern
- Multiple causes
- List 3 things that could be done to increase your confidence in a supported hypothesis
- Falsify all competing hypotheses
- Independent replication of experiments (when others get same results)
- Different experiments come at problem in another way and draw out same conclusion
- Give 2 reasons why we are never 100% sure about a supported hypothesis in science
- Experiments may have bias
2. There could be another hypothesis with the same prediction
- Give the atomic number and mass of an atom, explain the number and location of the protons, electrons, and neutrons
Ex. Iodine Atomic # 53
Atomic mass 127
127-53= 74 neutrons
Protons (+) 53
Electrons (-) 53
*protons and neutrons are located in nucleus (both have mass)
*electrons travel outside at speed of light
- Explain 3 things that are important in the bonding of atoms
- Electron shells tend to fill evenly
- Electrons tend to be in pairs
- The # of electrons and protons tends to balance so as to balance the overall charge
*8. Explain how ionic, covalent, and hydrogen bonds are formed. Contrast ionic, covalent, and hydrogen bonds for bond strength. Which dissociate in water (ionic or covalent)
Ionic- (2nd strongest) one atom steals an electron from another to fill electron shells evenly, atoms bond due to electrostatic attraction of negative and positive ions
Covalent- (strongest) bonds that are formed when pairs of electrons are shared between 2 atoms to fill electron shells evenly
Hydrogen- (weakest) form between polar molecules
Ex: Water- in the water molecule the larger nucleus of the oxygen atom tends to pull the electrons away from the hydrogen atoms. Giving the oxygen atom a - charge b/c the electrons spend more time around it and the hydrogens a + charge b/c their protons are exposed. Hydrogen bonds form between these weak + and - charges on molecules
- Proteins have 4 levels of structure, briefly describe them
- Primary- the sequence of amino acids in the protein (order matters)
- Secondary- the chain of amino acids forms a coil, due to hydrogen bonds
- Tertiary- the cool of amino acids folds back on itself due to cross linking of side groups on amino acids
- Quaternary- occurs when 2 or more separate amino acid chains bond together
*10. Explain in DETAIL what enzymes are and how they work? (Use terms such as catalyst and activation energy)
Enzymes are proteins that control chemical reactions. They act as biological catalysts, speeding up reactions by reducing the activation energy necessary for reactions to occur.
Activation energy- is the energy that must be added to a reaction to get it to proceed
*11. What is the significance of enzyme shape to their function? (Use the word substrate in your answer)
What 3 environmental factors affect protein shape?
The enzyme and the substrate must have the right 3-dimensional shape to bond together (lock and key concept), if their shapes don't match the reaction will not occur 3 environmental factors 1. Temperature 2. Ion concentration 3. Ph
- Explain 3 different ways that enzymes that can be turned off or on
- Environmental control - changing the environment changes the shape of enzymes (temp)
- Allosteric control- active site and Allosteric sites are where molecules bond to the enzyme. Allosteric molecules bond to Allosteric site with bond such as hydrogen bonds
- Covalent control- covalently bond molecules to the enzyme, takes another enzyme to remove a bond
- Contrast the following terms; acid, base, ph, and buffer
Acid- donate hydrogen ions (H+) produce an excess of H+ ions
Base- donate hydroxyl ions (OH-)
Ph- -log of the hydrogen ion concentration
Buffer- chemicals that tend to keep the ph of a solution from changing when either an acid or a base is added
- Define/contrast the following types of organic molecules: carbohydrates, lipids, and proteins
Carbs- (sugars) carbon, hydrogen, and oxygen in a 1:2:1 ratio. Used to store energy and are water soluble (monosaccharide, disaccharide)
Lipids- (fats) carbon and hydrogen in a 1:2 ratio, with little or no oxygen. Not soluble in water (saturated , unsat)
Proteins- have carbon, hydrogen, oxygen, and nitrogen! ( radical is the part that is different)
- Define/ contrast monosaccharide, disaccharide, and polysaccharides
Monosaccharide- one sugar, can’t be broken down to hydrolysis (water breakdown) b/c they have no dehydration bonds
Disaccharide- two sugars, can be broken down and are bonded together by a dehydration bond
Polysaccharide- more than 2 monosaccharides bonded together by dehydration links
