Bio Lab Test 2 Multiple Choice

What are the main characteristics of lipids?

Hydrophobic, store energy, form cell membranes, and include steroids like cholesterol

What are the key characteristics and functions of carbohydrates?

Composed of carbon, hydrogen, and oxygen; provide quick cellular energy, store energy as glycogen or starch, and provide structural support like cellulose

What are the properties of water?

It acts as an inorganic solvent, helps regulate temperature, and participates as a chemical reactant

What is the primary structure and function of triglycerides?

Long-term energy storage; made of one glycerol molecule and three fatty acids

What is the structure and role of a phospholipid?

They have a hydrophilic head and hydrophobic fatty acid tails that form a selective cell membrane bilayer

What are characteristics of proteins?

Composed of amino acids linked by peptide bonds; function as enzymes, transporters, and structural components

What are the functions of proteins?

Immunity, structure, transport, and catalysis (enzymes)

What are the structural building blocks of amino acids?

They contain an amino group, a carboxyl group, and a variable side chain (R group)

What is true of nucleic acids

They are made up of nucleotides, which consist of a nitrogenous base, a pentose sugar, and a phosphate group, and are involved in storing and expressing genetic information

What are the three components of a nucleotide (nucleic acid building block)?

Phosphate group, five-carbon sugar, and a nitrogenous base

What is a key difference between DNA and RNA?

DNA contains deoxyribose and uses thymine; RNA contains ribose and uses uracil

What are the key characteristics of ATP (adenosine triphosphate)?

Provides usable energy for cellular processes, contains three phosphate groups, and can be converted to ADP

What are the characteristics of enzymes?

They are proteins, act as biological catalysts, lower activation energy, generally increase the rate of chemical reactions

How does the active site of an enzyme function?

Its shape and chemical properties allow a specific substrate to bind, and it actively participates in catalysis

What is the role of a substrate in an enzyme-catalyzed reaction?

It is the specific reactant molecule that binds to the enzyme's active site and is converted into products

Which environmental factors can significantly affect enzyme activity?

Temperature, pH, substrate concentration, enzyme concentration, and inhibitors or activators

How does pH affect enzyme behavior?

Each enzyme has an optimal pH range; extreme pH changes amino acid charges and disrupts protein structure

What are some characteristics of enzyme specificity?

Act on substrates, contributes to substrate specificity which can depend on chemical properties, structure influence’s function.

What is activation energy and how do enzymes affect it?

It is the energy barrier a reaction must overcome, and enzymes lower it to speed up the reaction rate

What are the characteristics of a competitive inhibitor?

It competes directly with the substrate for the active site, reduces enzyme activity, and can be overcome by adding more substrate

What are the characteristics of pure noncompetitive inhibition?

It binds at a site other than the active site, reduces catalytic activity, (lowers Vmax), and cannot be overcome by extra substrate

What are characteristics of cofactors and coenzymes?

Some enzymes require cofactors to function, metal ions can act as cofactors, coenzymes are organic molecules, and coenzymes are derived from vitamins

What are examples of enzyme-catalyzed reactions in the human body?

Amylase breaking down starch, lipase breaking down fats, proteases breaking down proteins, and carbonic anhydrase catalyzing a reaction involving carbon dioxide and water

What happens as you increase substrate concentration in an enzyme-catalyzed reaction?

The reaction rate increases until enzymes become fully saturated, after which adding more substrate has no further effect

What statements are true about substrate concentration and its effect on enzyme activity?

Increasing substrate concentration can increase the reaction rate up to a point, enzymes can become saturated with substrate, and at saturation, adding more substrate has no further effect on the rate

What is true about reversible and irreversible enzyme inhibition?

Reversible inhibitors can dissociate from enzymes, irreversible inhibitors can permanently inactivate an enzyme, some irreversible inhibitors form covalent bonds with enzymes, and inhibition reduces the rate of an enzyme-catalyzed reaction

What causes protein denaturation and what does it do to an enzyme?

High temperatures and extreme pH disrupt a protein's normal 3D structure, reducing or stopping enzyme activity

What is the difference between anabolic and catabolic reactions?

Anabolic reactions build larger molecules and require energy, while catabolic reactions break down molecules and release energy

What is the difference between the Lock-and-Key and Induced-Fit models of enzyme action?

Lock-and-Key describes a rigid complementary fit, whereas Induced-Fit allows the active site to adjust slightly when the substrate binds

What is true about biological catalysts? (Enzymes)

Enzymes speed up reactions by lowering activation energy, can be used repeatedly, speed up both forward and reverse reactions in reversible processes, and help reactions occur rapidly at normal body temperature

What is the expected color change when Iodine is added to a starch solution? (negative to positive)

Yellow/brown to blue/purple

What is the color change observed when you add Benedict's reagent to a simple sugar solution (from a negative test to a positive test)?

Blue to green/red (or orange/brick-red)

What is the visible result when a drop of Catalase (from liver or potato) is added to hydrogen peroxide in a test tube?

Rapid bubbling and foam production of oxygen gas

In an enzyme lab, a student boils an amylase solution for 5 minutes, mixes it with starch, incubates it at 37°C, and then performs a Benedict's test (with heat). What color is the final solution?

Blue (indicating a negative test because boiling denatures the amylase, preventing it from breaking down starch into reducing sugars)

A student sets up a test tube containing starch and active salivary amylase, places it at 37°C for 15 minutes, and then adds a few drops of Iodine (Lugol’s solution). What is the expected final color of the solution?

Yellow (or brownish-yellow, indicating that the starch was successfully digested into maltose by the active amylase, leaving no starch for the iodine to react with)

During an enzyme lab, test tubes containing an enzyme and its substrate are placed in either an optimal pH 7 environment or an extreme pH 2 environment. Which tube yields a positive test result for product formation?

Only the pH 7 tube, because extreme pH denatures the enzyme

In the yeast fermentation lab, test tubes are filled with yeast plus various sugars or water. Which test tube will show the greatest gas accumulation?

The tube with live yeast and a fermentable sugar like glucose