Question

ap unit 1 exam
read each question carefully. write your response on the back of your exam answer paper.
question 1
the stems and fruits of pineapple plants contain a group of protein - digesting enzymes collectively called bromelain and often used as an antibrowning agent for fruits and vegetables. fruits and vegetables brown when they are bruised during transport or sliced and exposed to air. this browning is controlled by enzymatic pathways that produce brown pigments. the browning of fruits and vegetables reduces the nutritional value of the food, so antibrowning agents such as bromelain are used.
(a) identify the type of biomolecule monomer of which this enzyme is composed.
(b) bromelain works by breaking the enzymes that cause browning into smaller molecules. explain how the reaction that breaks up the enzymes occurs.
question 2
the diagram shows water molecules as solid ice at 0°c and as a liquid at 25°c.
(a) describe why hydrogen bonds form between water molecules.
(b) 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.
question 3
draw and label a bohr’s model of an atom hydrogen atom, include subatomic particles, charges, atomic mass, and atomic number.

Explanation:

(a) Enzymes are proteins, made of amino - acid monomers.
(b) Enzymes are broken by hydrolysis, adding water to break bonds.
(a) Water is polar, H has partial +, O has partial - for H - bond.
(b) Ice insulates water below, protects organisms.
Draw a nucleus with 1 proton (charge +1, atomic number 1), 1 electron in first shell.

Answer:

(a) Amino acid
(b) Hydrolysis reaction
(a) Due to polarity of water molecules
(b) Insulates water below
Draw nucleus with 1 proton, 1 electron in first shell.