Answer: Humans cannot synthesize them and must obtain them from diet.
- A They yield more usable ATP per gram than any other dietary fatty acid
- B Humans cannot synthesize them and must obtain them from diet
- C They represent a relatively minor class of unsaturated fatty acids found in the human diet
- D They are biologically required mainly during the early childhood growth period
Correct answer: B. Humans cannot synthesize them and must obtain them from diet
Explanation: Essential fatty acids (omega-3 like ALA; omega-6 like linoleic acid) cannot be synthesized by humans because we lack the enzymes to introduce double bonds beyond C9. They must come from food.
As substrate concentration rises, reaction rate increases steeply at first, then plateaus at Vmax once every enzyme molecule is working at full capacity; Km is the substrate concentration giving half-maximal rate, and a LOWER Km means the enzyme reaches that rate with less substrate (higher affinity).
Concept context
Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.