Biology Midterm 2011
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What are the steps of the Scientific Method?
2.Form a hypothesis
- 3.Test the hypothesis by performing a controlled
4.Record and analyze the results
5.State the conclusion
What are the eight characteristics of all living
1)All living things are made of one or more cells
2)All living things reproduce
3)All living things contain genetic material
4)All living things grow and develop
5)All living things obtain and use energy
- 6)All living things respond to stimuli (their
7)All living things maintain homeostasis
8)All living things evolve
What is an atom?
smallest unit of matter
What is the mass number of an element?
sum of the protons and neutrons
What 6 elements make up 98% of the body weight of organisms?
CHNOPS: carbon, hydrogen, nitrogen, oxygen, phosphorous, sulfur
What are isotopes? What happens if an isotope is unstable?
- atoms of the same element with a different number of neutrons
- unstable isotopes are radioactive-gives off energy and throws off particles
What is ionic bonding?
valence electrons are transferred from one atom to another, causing each atom to have a charge
What are the two kinds of ions?
- Cation (positive)
- Anion (negative)
What are polyatomic ions?
groups of atoms of more than one kind of element attached by covalent bonds
What is covalent bonding?
- two atoms share valence electrons so each atom has a complete outer shell
- stronger than an ionic bond
What is a polar molecule?
molecule with uneven charge distribution
How are polar and non-polar covalent bonds formed?
- polar: formed due to unequal sharing of electrons between atoms
- non-polar: formed when sharing of electrons between atoms is equal
What is the difference between exothermic and endothermic reactions?
- exothermic- produces heat
- endothermic- requires heat
Why is water a good solvent?
it can dissolve ionic compounds due to its polarity
What are hydrogen bonds?
- they are formed when the positive (hydrogen) end of one water molecule is attracted to the negative (oxygen) end of another water molecule
- individually they are not strong, but as a group they are
What are the four properties of water?
- 1. high heat capacity (large number of hydrogen bonds can absorb heat without a large change in temperature)
- 2. high heat of vaporization (large number of hydrogen bonds must be broken to evaporate water)
- 3. cohesive and adhesive (attracted to itself, attracted to other things)
- 4. high surface tension (frozen water is less dense than liquid water)
What's the difference between acids and bases?
- Acids are substances that dissolve in water, releasing hydrogen ions (H+)
- Bases are substances that either take up hydrogen ions (H+) or release hydroxide ions (OH-)
What is the difference between organic and inorganic molecules?
- organic require carbon and hydrogen
- inorganic are held together by covalent bonds, and organic are held together by ionic bonds
What are functional groups?
specific combinations of bonded atoms that always react in the same manner, regardless of the particular carbon skeleton
What are isomers?
organic molecules that have identical molecular formulas but a different arrangement of atoms
What are polymers?
large molecules made by joining smaller units (monomers) together in long chains
What is dehydration synthesis?
- a chemical reaction joining monomers of organic compounds to make polymers
- opposite is hydrolysis
What is the simplest sugar?
What are three examples of monosaccharides?
What are three examples of disaccharides?
- sucrose- glucose and fructose
- maltose- 2 glucose
- lactose- glucose and galactose
What are four examples of polysaccharides?
What are the five main groups of lipids? What characterizes a lipid?
- *all lipids contain either hydrocarbon chains or fatty acids except steroids*
What makes up a fatty acid?
- long hydrocarbon chain
- carboxyl group (COOH/COO-)
What do fats and oils consist of?
one molecule of glycerol linked to one, two, or three fatty acids
What's the difference between saturated and unsaturated fatty acids?
- unsaturated contain at least one double bond between the carbons, which causes the fatty acid to bend and push apart instead of tightly stacking together, so it becomes fluid (oils)
- saturated contains no double bonds between the carbons, so it can stack easily and is a solid (fats)
What is trans fat? How is it different from cis fat?
- trans fat is unsaturated, but it can be stacked into a solid because the hydrogens are on opposite sides of the double-bonded carbons so they DON'T BEND
- cis fat is normal unsaturated fatty acids, where the hydrogens are on the same side so it bends
What is a phospholipid?
- made up of two fatty acids (at least one must be unsaturated), glycerol, and a phosphate group
- amphipathic: one side is hydrophobic (tails) and one is hydrophilic (heads)
What is a steroid? Give an example.
- steroids have skeletons of 4 fused carbon rings
What are waxes? Name the three characteristics of waxes.
- a long-chain fatty acid bonded with a long-chain alcohol
- 1. high melting point
- 2. waterproof
- 3. resistant to degradation because of length
What are the two functions of nucleic acids?
- carry genetic information
- dictate the amino acid sequence of proteins to perform basic life processes
What is the basic unit of nucleic acids?
nucleotides (nitrogen base, sugar, phosphate) connected to form long chains
What's the difference between DNA and RNA?
- DNA doesn't contain oxygen, while RNA does
- DNA is double stranded to form a double helix, while RNA is single stranded
- DNA stores genetic info, and RNA carries genetic info from the DNA
Which nitrogen bases are found in DNA and RNA?
- DNA- adenine, guanine, cytosine, thymine
- RNA- adenine, guanine, cytosine, uracil
What is a protein made up of?
long chain of amino acids (polypeptide)
What is the most abundant biomolecule?
What is the structure of an amino acid?
amino group, carboxyl group, central carbon
What is a peptide bond?
a covalent bond connecting two amino acids
What are the six functions of proteins?
- 1. enzymes: helps reactions occur more easily
- 2. transport: moves nutrients/molecules
- 3. structure/support: supports structures in cells or tissues
- 4. defense: wards off disease and infection
- 5. hormones: serves as intercellular messages
- 6. motion: moves molecules or tissues
What are anabolic reactions?
"building up" reactions, or synthesis
What are catabolic reactions?
"breaking down" reactions, or decomposition
What are enzymes? What is their function?
- catalysts for biological reactions
- they lower activation energy to speed up reactions
What do the names of enzymes tell about them?
- can identify the reactant
- sucrase: cuts sucrose
- can describe its function
- oxidase: catalyzes oxidation
What is metabolism?
consists of all chemical activities and changes that take place continuously in a cell or organism
What is an active site?
where the substrate (reactant) binds to the enzyme
What are four factors that affect enzymes?
- substrate concentration
What's the difference between an activator and an inhibitor?
activators increase enzyme activity, and inhibitors decrease enzyme activity
What's the difference between a competitive inhibitor and a non-competitive inhibitor?
- competitive: has a similar structure to substrate, binds to active site of enzyme
- non-competitive: doesn't have similar structure, binds to allosteric site which changes the shape of active site
What is denaturization?
when the enzyme's structure is altered
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