Biology Quiz
Questions: 16 · 10 minutes
1. Why does an enzyme usually catalyze only one reaction or a small group of closely related reactions?
Its active site has chemical and structural properties suited to particular substrates
It supplies a different genetic code for every substrate
It can bind only molecules that are larger than the enzyme
Its fatty acid tails repel all unrelated products
2. Which type of monomer is used to build proteins?
Fatty acids
Monosaccharides
Nucleotides
Amino acids
3. Which feature allows phospholipids to form bilayers in water?
They consist entirely of nonpolar fatty acids
They contain repeating amino acid units
They form covalent bonds with surrounding water molecules
They have hydrophilic heads and hydrophobic tails
4. Which element is characteristically present in amino acids but not in the basic structure of most carbohydrates and fats?
Nitrogen
Carbon
Hydrogen
Oxygen
5. Which nitrogenous base is normally found in RNA instead of thymine?
Cytosine
Adenine
Guanine
Uracil
6. A student adds iodine solution to a food sample, and the mixture turns blue-black. Which molecule is indicated?
Starch
Reducing sugar
Protein
Lipid
7. During digestion, a large biological molecule is split into smaller units by hydrolysis. What role does water play?
It removes all oxygen atoms from the molecule
It is used when a covalent bond between subunits is broken
It joins the subunits by creating an additional peptide chain
It converts every subunit into a fatty acid
8. A food sample turns violet when mixed with Biuret reagent. Which conclusion is best supported?
The sample contains a reducing sugar
The sample contains a substantial amount of starch
The sample contains peptide bonds associated with protein
The sample contains only unsaturated lipids
9. Which polysaccharide provides structural support in plant cell walls?
Glycogen
Cellulose
Starch
Chitin
10. Which statement best compares saturated and unsaturated fatty acids?
Saturated fatty acids contain nucleotides, while unsaturated fatty acids contain amino acids
Saturated fatty acids always have shorter chains than unsaturated fatty acids
Unsaturated fatty acids contain carbon-carbon double bonds that can create bends in their chains
Unsaturated fatty acids lack carbon and hydrogen bonds
11. After Benedict's solution is added to a sample and heated, an orange precipitate appears. What does this indicate?
A high concentration of protein
The presence of a reducing sugar
The presence of DNA
The presence of starch
12. An enzyme is exposed to a temperature far above its usual working range and permanently loses activity. What most likely happened?
Its substrate was converted into an enzyme
Its three-dimensional shape changed, disrupting the active site
Its peptide bonds were replaced by glycosidic bonds
Its activation energy increased because more enzyme was produced
13. Which sugar is present in DNA nucleotides?
Ribose
Glucose
Deoxyribose
Fructose
14. Which combination forms a typical triglyceride molecule?
One phosphate, one sugar, and one base
Three glycerol molecules and one fatty acid
One glycerol and three fatty acids
A chain of amino acids with three glycerol groups
15. Two monosaccharides join to form a disaccharide, releasing a water molecule. What type of reaction occurred?
Hydrolysis
Neutralization
Phosphorylation
Condensation
16. A cell must keep its membrane fluid as the surrounding temperature falls. Which change in membrane lipids would generally help?
Increasing the proportion of unsaturated fatty acid tails
Removing the hydrophilic heads from phospholipids
Increasing the proportion of fully saturated fatty acid tails
Replacing phospholipids with long protein fibers