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, _________, 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 _______ to the bottom of the body of water.