Biology 115 Midterm Exam 2025

Biology 115 Midterm Exam 2025 Biology - -The study of the structure and function of the living world Scientific Theory - -A well supported explanation for a very general phenomenon List steps of the scientific process - -1. observation/question 2. Develop hypothesis 3. Design experiment 4. Make predictions 5. Data collection 6. Conclusions What two things must every hypothesis have? - -testability and falsifiability What is a null hypothesis? - -the opposite of the hypothesis; refutes original hypothesis Independent variable - -variable being changed Dependent variable - -the effect of the independent variables; the data being collected What is a positive control? - -A group that is expected to show support for the hypothesis (shows that it is possible) What is a negative control? - -a group in which no response is expected What is matter? - -anything that takes up space and has mass What 4 elements make up 96% of living matter? - -carbon, hydrogen, oxygen, nitrogen Atomic number - -number of protons Mass number - -number of protons + neutrons What is an orbital? - -Regions where electrons orbit a nucleus What is are valence electrons? - -electrons found at the outer-most shell What is the max number of electrons that can be found on the innermost shell? - -2 electrons (2 shells with 1 electron each) What is the max number of electrons that can be found on all other electron shells? - -8 (2 shells with 4 electrons each) Biology Biology Biology What is a covalent bond? - -When atoms share electrons What is a non-polar covalent bond? - -electrons are shared equally. They are hydrophobic because of this. What is a polar covalent bond? - -electrons are not shared equally. creates partial charges on atoms. What is an ionic bond? - -complete transfer of electrons Cation - -positively charged ion due to loss of electrons Anion - -negatively charged ion due to gaining electrons What is a hydrogen bond? - -A weak bond formed by the partial charges of polar molecules Why does water expand as it freezes? - -Lower temperature forces the hydrogen bonds to become stable, which pushes the water molecules farther apart from each other than when in a liquid state. How does cohesion and adhesion of water form a meniscus when in a tube? - Adhesion bonds the molecules to the sides of the container, while cohesion pulls the middle of the water to the bottom. What is pH? - -the "potential of hydrogen", or the measurement of the concentrations of H+ ions in a liquid What is a condensation reaction? - -A covalent bond between monomers that produces a water molecule. What is hydrolysis? - -Separation of monomers by adding a water molecule What is the monomer of proteins? - -amino acids What are the 6 functions of proteins? - -enzymes, transportation, structure, signaling, antibodies, and movement What is an example of how proteins transport things? - -hemoglobin transports oxygen; sodium-potassium pump What are the main components of the structure of an amino acid? - -A central carbon, an amino group, a carboxyl group, and the R side chain What is the significance of the R group in amino acids? - -It determines which of the 20 amino acids it will be, as well as its properties, like charge and polarity. Biology Biology What is the N-terminus and C-terminus? - -The N terminus is the end with the amino group, and the C-terminus is the end with the carboxyl group. What is a peptide bond? - -a covalent bond between the N and C terminus of 2 amino acids What is the difference in a peptide and a polypeptide? - -a peptide has less than 50 amino acids, and a polypeptide has more than 50 amino acids. What is the monomer of a nucleic acid? - -nucleotide What is the function of DNA? - -stores genetic information What is the function of RNA? - -It copies information from DNA and uses it to make proteins. What are the 3 components of a nucleotide? - -sugar, phosphate, nitrogenous base What is the difference in the sugars of DNA and RNA? - -DNA has deoxyribose and RNA has ribose. deoxyribose has one less oxygen atom than ribose. What nitrogenous bases does DNA contain? - -A, G, C, and T. (adenine, guanine, cytosine, and thymine) What nitrogenous bases does RNA have? - -A, G, C, and U. (adenine, guanine, cytosine, and uracil) Which end of a nucleotide is the 3' end and which is the 5' end? - -3' end is the sugar, and the 5' end is the phosphate What is a phosphodiester bond? - -covalent bond between the 3' and 5' ends of nucleotides What causes DNA to be double stranded? - -hydrogen bonds between cytosine & guanine and adenine and thymine. What are 3 functions of carbohydrates? - -energy storage, structure, cell identity What forms of energy storage do plants and animals use? - -plants use starch, and animals use glycogen What is the monomer of a carbohydrate? - -monosaccharides Biology Biology What is the difference between an aldose sugar and a ketose sugar - -aldose sugars have a carbonyl group attached to the end of the chain, and ketose sugars have the carbonyl group attached to an interior C What type of bond do carbohydrates have? - -glycosidic bond What makes lipids hydrophobic? - -the high number of hydrocarbon bonds, which have no partial charges What is the monomer of lipids? - -glycerol and fatty acids What is a saturated fat? - -contains only single bonds in hydrocarbon chains. What is an unsaturated fat? - -the fatty acid chains contain one or more double bonds between H-C What type of bond bonds lipids together? - -Ester bonds What is the primary structure of a protein? - -the sequence of amino acids What makes up the secondary structure of proteins? - -hydrogen bonds forming between amino acids, forming alpha helices and beta pleated sheets. What is the tertiary structure of a protein? - -The whole 3-D model of the protein, formed by folding of the chain, caused by hydrogen bonds, ionic bonds, and hydrophobic effects. What is the quaternary structure of a protein? - -two or more polypeptide chains joined to form a larger protein What is denaturation of a protein and how can it happen? - -when it loses its shape or structure. can be caused by changes in pH or increasing temperature. What is a prion? - -improperly folded proteins that cause infectious diseases (like mad cow disease) What is a substrate? - -a reactant substance that bonds to an enzyme How do enzymatic reactions work? - -a substrate binds to a specific active site on the enzyme, a chemical change occurs, then the products are released. Enzyme remains unchanged. What is competitive inhibition? - -a substance competes for the active site of the enzyme, so it lowers the amount of substrate that bonds to the enzyme. Biology Biology What is non-competitive inhibition? - -a substance binds to an enzyme not on the active site, and changes the shape of the enzyme, which deactivates it. What is feedback inhibition? - -The products of a reaction allosterically bind to the enzyme to deactivate the reactions. What 2 types of starch do plants use as energy storage? - -amylose and amylopectin Whats the structural difference between amylose and amylopectin? - -amylose is unbranched; amylopectin is slightly branched. What is the structure of glycogen? - -a highly branched molecule What types of carbohydrates does plants, fungi, and bacteria use as structural support? - -plants use cellulose, fungi uses chitin, and bacteria uses peptidoglycan What are the main differences between DNA and RNA? - -type of sugar, types of nitrogenous bases, and the number of strands What is the primary structure of DNA and RNA? - -the long sequence of nucleotides What is the secondary structure of DNA? - -the double helix What is the secondary structure of RNA? - -loops and helices called "stems" Who was the original researcher who discovered the structure of DNA? - -rosalind franklin, who's work was stolen by watson and crick What does ATP stand for? - -adenosine triphosphate How does ATP create energy? - -breaking off phosphate groups by hydrolysis releases energy What can the phosphates that break off from ATP do? - -they can be used as allosteric inhibitors (or activators) of enzymes. What makes up the head of a phospholipid? - -choline, phosphate, and glycerol Which part of a phospholipid is hydrophobic? - -the fatty acid tails What is a micelle? - -A sphere 1 layer of phospholipids thick that contain no water on the inside. What is a liposome? - -A phospholipid bilayer that contains water on the inside.