Essential amino acids are those that______________

Question

BlackTom AI · Accepted Answer

Essential amino acids cannot be synthesized in adequate amounts by the human body and therefore must be supplied through the diet.

Relevant knowledge points and concepts:
- Amino acids are building blocks of proteins; the body needs twenty standard amino acids to make proteins and perform metabolic functions.
- "Essential" amino acids are those the body cannot produce (or cannot produce in sufficient quantity) and so must be consumed.
- Adults require nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Some amino acids (e.g., arginine) are conditionally essential in certain life stages or illnesses.

Step-by-step reasoning:
1. Determine definition: essential = must be obtained externally because endogenous synthesis is insufficient.
2. Apply to choices: any true statement about essential amino acids must reflect dietary necessity.
3. Evaluate each answer:
   - "Are not needed by the body": If an amino acid were not needed, it wouldn’t be labeled essential. This contradicts the definition.
   - "Must be obtained from diet": Matches the definition exactly — essential amino acids are required in the diet.
   - "Can be synthesized by the body": This is the opposite of essential; those that can be synthesized are called nonessential amino acids.
   - "Are only found in plants": Essential amino acids occur in both plant and animal proteins; many animal proteins are complete sources containing all essential amino acids.

Why the correct answer is correct:
Because the defining property of essential amino acids is that endogenous synthesis is absent or insufficient, dietary intake is necessary to meet physiological needs. Failure to consume adequate amounts leads to impaired protein synthesis and clinical deficiency symptoms.

Other options are incorrect: they contradict the definition (not needed; can be synthesized) or make a false exclusivity claim (only found in plants).

Conclusion: The correct answer is "Must be obtained from diet," which matches the provided answer.

Essential amino acids are those that______________单项选择题

类似问题

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3. The amino acid methionine is characterized by __________side chain

__________ amino acids can be produced in the body.

The building blocks for the creation of proteins are _____________________________________.

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