Question

section d: macromolecules
d1) complete the table. use short phrases.
macromolecule | main job / function | example(s) | energy (cal/g)
carbohydrate | | |
lipid | | |
protein | | |
nucleic acid | | |

d2) short answer: why do lipids store more energy per gram than carbohydrates? (1-2 sentences)
answer:

d3) calculation practice: use 4 cal/g for carbohydrates and proteins, 9 cal/g for lipids, and 0 cal/g for nucleic acids.
a) 20 g carbohydrates = ______ cal
b) 8 g lipids = ______ cal
c) 15 g proteins = ______ cal

section e: building and breaking polymers
e1) fill in the blanks to describe the two reactions.
dehydration synthesis: monomers → polymer + ______ (water).
hydrolysis: polymer + ______ (water) → monomers.
e2) short answer: explain why enzymes are important in reactions in living things.
answer:

Explanation:

D1) Completing the Table

Macromolecule	Main job / function	Example(s)	Energy (cal/g)
Lipid	Energy storage (long - term), insulation, cell membrane component	Fats, Oils, Cholesterol	9
Protein	Enzymes (catalyze reactions), structural support, transport, defense	Hemoglobin, Insulin, Collagen	4
Nucleic Acid	Store and transmit genetic information	DNA, RNA	0

D2) Short Answer

Lipids have more carbon - hydrogen bonds and fewer oxygen atoms compared to carbohydrates. When these bonds are broken during metabolism, more energy is released per gram.

D3) Calculation Practice

a) 20 g carbohydrates

Step1: Recall the energy value for carbohydrates

The energy value for carbohydrates is 4 cal/g.

Step2: Calculate the energy

Energy = mass×energy per gram = $20\ g\times4\ cal/g = 80\ cal$

Step1: Recall the energy value for lipids

The energy value for lipids is 9 cal/g.

Step2: Calculate the energy

Energy = mass×energy per gram = $8\ g\times9\ cal/g = 72\ cal$

Step1: Recall the energy value for proteins

The energy value for proteins is 4 cal/g.

Step2: Calculate the energy

Energy = mass×energy per gram = $15\ g\times4\ cal/g = 60\ cal$

Answer:

80

b) 8 g lipids