AP Bio 1.5 - Free Response Question - 24 Jan 25

1.5 Structure and Function of Biological Macromolecules

Hydrogen bonds water and ice (FRQ)

Fill in the blank

SYI-1.A.3:

The hydrogen bonds between water molecules

result in cohesion, (a)   , and surface tension.

1.5 Structure and Function of Biological Macromolecules

Hydrogen bonds water and ice (FRQ)

Question: Describe why hydrogen bonds form between water molecules.

Answer: Slightly ​ (a)   charged O atom in one water molecule is attracted to one of the slightly ​ (b)   charged H atoms in another water molecule, so that a ​ (c)   hydrogen bond forms between the two water molecules. The response explains that the strong ​ (d)   of O pulls the electrons shared with each H atom within a single water molecule toward the O atom, concentrating more ​ (e)   charge at the O end of the molecule and giving the H atoms a slight positive charge.

• negatively
• positively
• electronegativity
• negative
• weak
• strong
• positive

1.5 Structure and Function of Biological Macromolecules

Hydrogen bonds water and ice (FRQ)

Explain why the arrangement of water molecules is different in ice and water.

Answer: As water cools, the water molecules ​ (a)   down and, as a result, the hydrogen bonds between them become more stable. Hence, as ice forms the ​ (b)   bonds cause the water molecules to space out in a crystalline form. Since the liquid water molecules are at a ​ (c)   temperature, the molecules are moving ​ (d)   rapidly and are ​ (e)   forming and breaking their hydrogen bonds.

• strong
• positive
• slow
• hydrogen
• greater
• more
• constantly
• fast
• less
• constant

1.5 Structure and Function of Biological Macromolecules

Hydrogen bonds water and ice (FRQ)

Question: To help explain surface tension, use a single water molecule in the template and draw arrows

representing the possible locations of hydrogen bonds formed by the molecule. The possible hydrogen

bonds formed by a water molecule below the surface are shown.

Answer:

The response has arrows drawn from ​ (a)   of the water ​ (b)   at the surface of the water that show possible hydrogen ​ (c)   to other water molecules alongside and just ​ (d)   the molecule at the ​ (e)   .

• two
• molecule
• bond
• less
• above
• one
• molecules
• bonds
• below
• surface

1.5 Structure and Function of Biological Macromolecules

Hydrogen bonds water and ice (FRQ)

Fill in the blank

Question: The arrangement of the water molecules in ice causes the ice to float. Explain how ice floating on the surface of a body of water affects the water in a way that is beneficial to the organisms in it.

Answer: The floating ice will reduce heat loss from the water below the ice, resulting in warmer water that is not likely to (a)   to the bottom of the body of water.