Question

1. which organic molecule provides energy for the body?

a) lipids
b) proteins
c) carbohydrates
d) nucleic acids
extra credit (2 points)

1. what is the difference between a covalent bond and a hydrogen bond?

a) covalent bonds are stronger and involve the sharing of electrons; hydrogen bonds are weaker and involve an attraction between partial charges.
b) covalent bonds are weaker and involve the sharing of electrons; hydrogen bonds are stronger and involve the transfer of electrons.
c) covalent bonds involve the transfer of electrons; hydrogen bonds involve the sharing of electrons.
d) both are equally strong and involve the sharing of electrons.
part ii: true/false (2 points each, 20 points total)
instructions: write t for true or f for false for each statement on the answer sheet.

1. the first law of thermodynamics states that energy can be created but not destroyed.
2. catabolism involves breaking down large molecules into smaller ones.
3. enzymes are consumed during a reaction.
4. a hypotonic solution will cause a plant cell to shrink.
5. active transport requires an input of energy from the cell.

Explanation:

• For question 20: Lipids, proteins, and carbohydrates can provide energy for the body. Nucleic acids store and transmit genetic information and do not directly provide energy for the body's metabolic work.
• For question 21: Covalent bonds involve sharing of electrons between atoms and are strong. Hydrogen bonds are weaker and are attractions between partial - charges.
• For part II - 1: The first law of thermodynamics states that energy cannot be created or destroyed, only converted from one form to another.
• For part II - 2: Catabolism is the process of breaking down large molecules into smaller ones to release energy.
• For part II - 3: Enzymes are catalysts and are not consumed during a reaction.
• For part II - 4: A hypotonic solution causes a plant cell to swell as water moves into the cell.
• For part II - 5: Active transport moves substances against their concentration gradient and requires energy input from the cell.

Answer:

1. d) Nucleic Acids
2. a) Covalent bonds are stronger and involve the sharing of electrons; hydrogen bonds are weaker and involve an attraction between partial charges.

Part II - 1: F
Part II - 2: T
Part II - 3: F
Part II - 4: F
Part II - 5: T