Macromolecules
Why is DNA with more G–C bonds more stable than DNA with more A-T bonds?
G-C make 3 H-bonds while A-T make 2 H Bonds
Describe the cell type (by surface-area-to-volume ratio) that exchanges gases most rapidly
Larger surface area to volume ratio
Water's biological importance stems from its polarity and resulting hydrogen bonds, which give it properties like cohesion, adhesion, high specific heat, being an excellent solvent, and less dense ice. These properties allow water to regulate temperature, facilitate chemical reactions as a solvent, transport nutrients through capillary action, and create habitats by floating on ice.
What property of water allows water to move up plants?
What property of water allows ice to float?
capilarry action
density
Why does enzyme reaction rate plateau over time?
Substrate becomes limiting or enzymes reach Vmax.
What happens to oxygen production in plants as light intensity increases? Why?
Oxygen production increases, indicating higher photosynthetic rate
What type of molecule is shown by a phosphate group, 5 carbon sugar, and nitrogenous base?
Nucleotide
Which organelle has folded membranes to increase surface area for reactions?
1 point per organelle
Chloroplast
Mitochondria
ER
Why does the mass of plant tissue not change in isotonic sucrose solution?
Water movement in and out is balanced (equal solute concentration
What happens to an enzyme when pH or temperature is extreme?
It denatures — loses shape and function because the bonds between the R-Groups broke
What stage of cellular respiration does not occur in the mitochondra and where does this stage occur?
Glycolysis ---> Cytoplasm
Cholesterol molecules (lipids) are found between the phospholipids in animal cell membranes. Why can cholesterol embed itself in the plasma membrane?
Cholesterol is largely nonpolar, allowing it to interact with the hydrophobic fatty acid tails inside the phospholipid bilayer.
How does compartmentalization benefit eukaryotic cells?
Separates metabolic processes for efficiency and regulation.
A cell contains a high concentration of potassium ions (K⁺) and a low concentration of sodium ions (Na⁺) compared to its surroundings. Despite this, the cell continuously pumps K⁺ in and Na⁺ out.
What type of transport is occurring?
Active transport
A patient takes the drug statin, which binds to the active site of the enzyme HMG-CoA reductase—the enzyme responsible for producing cholesterol in the liver. When the statin is present, cholesterol synthesis decreases because the enzyme cannot bind its natural substrate. What kind of inhibitor is statin and why?
Type: Competitive inhibitor.
Explanation: Statin competes with the natural substrate for the enzyme’s active site, preventing substrate binding. The inhibition can be overcome by increasing substrate concentration.
What energy organelles are found in producers and what energy organelles are found in consumers?
Producers: Chloroplast and Mitochondria
Consumers: Mitochondria
The rough er (ands its ribosomes), the golgi apparatus, vescicles, and cell membrane work together to synthesize, fold, and secrete what macromolecule
Protein
Why are mitochondria and chloroplasts considered evidence of endosymbiosis?
They contain their own DNA and double membranes
Water moves in what direction for the following categories:
Water Concentration
Solute Concentration
Water Potential
High --> Low Water Concentration
Low --> High Solute Concentration
High --> Low Water Potential
(less negative --> more negative)
Why is enzyme structure critical for its function, and how does denaturation affect this?
changes shape of active site --> cant bind to substrate
How are photosynthesis and cellular respiration connected?
Photosynthesis products (glucose + O₂) are reactants for respiration and vice versa
What are the chemical compositions of the organic macromolecules?
Organic = C - H
Inorganic = O, N, P, S
Lipid: CHOP
Carbohydrate: CHO
Protein: CHONS
NA: CHONP
Phospholipids have sections that are polar, nonpolar, hydrophobic, and hydrophilic. Match the sections to their characteristics
head: polar, hydrophilic
tail: nonpolar, hydrophobic
Water moves across cell membranes much faster than expected by simple diffusion, yet no ATP is used. What structure in the cell membrane makes this possible, and what type of transport is it?
Aquaporins
Faciliated Diffusion
A scientist discovers a mutation that changes the amino acid's primary structure (the order of animo acids). What will be the effect on the enzyme's function and why?
The enzyme would have changes to the secondary and tertiary structure because the folding would be changed, which changes the structure of the active site because the R-Groups are interacting differently
Many steps of cellular respiration are regulated by feedback inhibition. Explain this process
Process: Feedback inhibition occurs when the end product of a metabolic pathway (such as ATP or citrate) binds to an allosteric site on an enzyme earlier in the pathway (like phosphofructokinase in glycolysis). This binding changes the enzyme’s shape, reducing its activity and slowing further production.
Purpose: It prevents the cell from wasting energy or overproducing ATP when enough has already been made, maintaining metabolic balance and efficiency.