Unit 1 - Chemistry of Life

Which property of water allows a water strider to walk on the surface of a pond without sinking?

Surface tension resulting from cohesive hydrogen bonding

A researcher is studying a molecule and finds it contains carbon, hydrogen, and oxygen in a ratio of 1:2:1. Which class of macromolecules is this most likely to be?

Carbohydrates

The synthesis of a polysaccharide from several glucose monomers involves which type of chemical reaction?

Dehydration Synthesis

How do the structures of starch and cellulose differ, despite both being polymers of glucose?

The orientation of the glycosidic linkages leads to different 3D shapes

Which of the following describes the secondary structure of a protein?

The local folding into alpha-helices or beta-pleated sheets stabilized by hydrogen bonds

In the Hershey-Chase experiment, what evidence supported the conclusion that DNA, not protein, was the genetic material?

Radioactive phosphorus (32P) was found inside the infected bacterial cells

What is the primary reason that oil and water do not mix?

Oil molecules are nonpolar and cannot form hydrogen bonds with water

A polypeptide is being synthesized. To which end of the growing chain is the next amino acid added?

The carboxyl (C-) terminus

Which of the following best describes the structure of a nucleotide?

A five-carbon sugar, a nitrogenous base, and a phosphate group

If a DNA sample is found to contain 30% adenine, what is the expected percentage of cytosine based on Chargaff's rules?

20%

What is a key structural difference between DNA and RNA nucleotides?

DNA contains deoxyribose sugar, while RNA contains ribose sugar

Which level of protein structure is most directly affected by a single amino acid substitution in a polypeptide chain?

Primary structure

Why are unsaturated fats usually liquid at room temperature?

Double bonds in the fatty acid tails create kinks that prevent tight packing

Which of the following describes the antiparallel nature of the DNA double helix?

One strand runs in the 5’ to 3’ direction, while the other runs 3’ to 5’

What was the significance of the Miller-Urey experiment?

It demonstrated that organic molecules like amino acids could form under prebiotic conditions

Which functional group is found at the 5′ end of a DNA strand?

Phosphate group

A protein is placed in a high-temperature environment and loses its function. Which of the following has most likely occurred?

The hydrogen bonds and R-group interactions were disrupted, causing the protein to unfold

Which element is found in both nucleic acids and proteins, but not in typical lipids or carbohydrates?

Nitrogen

In a phospholipid, what is the chemical nature of the 'tail' region?

Hydrophobic and nonpolar

What type of bond holds the two strands of a DNA molecule together between the nitrogenous bases?

Hydrogen bonds

Which of the following is an example of a purine nitrogenous base?

Guanine

How does the high specific heat of water benefit living organisms?

It helps maintain stable internal and environmental temperatures

Which interaction is most important for the formation of a protein's tertiary structure?

Interactions between the R-groups (side chains) of amino acids

What is the result of a hydrolysis reaction involving a disaccharide like maltose?

Two monosaccharides (glucose) are produced

Which of the following describes a saturated fatty acid?

A hydrocarbon chain with no double bonds, maximizing the number of hydrogens

Which level of taxonomy is the most inclusive?

Domain

Water is considered a polar molecule because:

Oxygen is more electronegative than hydrogen, leading to unequal electron sharing

Which type of isomer has the same chemical formula but different atom connectivity?

Structural isomers

What is the primary function of the polysaccharide chitin?

Structural support in the exoskeletons of insects and fungal cell walls

Which of the following statements about DNA replication directionality is correct?

New nucleotides are always added to the 3’ end of the growing strand