Which of the following statements about nutrients is true?

Correct Answer: A

Rationale: All nutrient classes carbohydrates, lipids, proteins (macronutrients), vitamins, minerals (micronutrients) are essential for survival, supporting energy, structure, and regulation. Micronutrients like vitamin D can be stored, not daily required. Carbohydrates, lipids, proteins are macronutrients, not micro. Macronutrients aren't vitamins/minerals, those are micro. Essentiality of all, per nutrition, makes 'a' true.

Correct Answer: C

Rationale: Lactic acid accumulates in fatigued skeletal muscles when oxygen supply lags demand, shifting metabolism to anaerobic glycolysis. Normally, pyruvate from glucose enters mitochondria for aerobic respiration, yielding ATP efficiently. During intense exercise, oxygen depletion forces pyruvate conversion to lactate via lactate dehydrogenase, releasing NAD+ to sustain glycolysis and ATP production, though less efficiently. This occurs in skeletal muscle, not exclusively cardiac, which relies more on aerobic pathways. Rested muscles with oxygen use aerobic metabolism, avoiding lactate buildup. Fatigued muscles with oxygen continue aerobic respiration, not glycolysis. Rested muscles lacking oxygen are hypothetical, as rest implies oxygen availability. Exercise physiology confirms lactate rises in anaerobic conditions blood levels can jump from 1 to 20 mmol/L in fatigue causing acidity and signaling exhaustion. This adaptive mechanism delays fatigue, distinguishing it from aerobic states or unrelated muscle types, a key insight into metabolic flexibility.

Correct Answer: B

Rationale: For an immobilized patient, maintaining joint and muscle function is a priority, and contractures permanent shortening of muscles or tendons due to prolonged immobility are a significant risk. Positioning and ROM exercises keep joints flexible and muscles stretched, counteracting the tendency for tissues to stiffen and shorten when unused. Increased pain might occur with immobility, but ROM exercises primarily address stiffness rather than pain itself. Pressure ulcers result from prolonged pressure on skin, prevented more by repositioning than ROM alone. Compromised circulation can occur with immobility, but it's more directly managed by elevation or compression, not ROM exercises. Contractures are the most relevant outcome these interventions target, as they can lead to permanent disability if not addressed early, making this the primary focus of such care in immobilization scenarios.

Correct Answer: A

Rationale: Joints are stabilized by structures connecting bones directly. Ligaments are tough, fibrous tissues linking bone to bone, providing stability and limiting excessive movement, like the ACL in the knee. Tendons connect muscle to bone, facilitating movement, not joint union. Muscles generate force but don't join bones structurally. Cartilage cushions joints but doesn't bind bones together. Ligaments are the anatomical answer, as their primary role is maintaining joint integrity, distinguishing them from the other options focused on movement or padding rather than connection.

Correct Answer: A

Rationale: Rheumatic arthritis requires exercises to maintain joint mobility and strength, but they must be tailored to avoid worsening inflammation. Doing them daily, 3-10 times per joint, promotes consistency and flexibility without overexertion, fitting a balanced program. Exercising during active inflammation can damage joints further, as rest is then advised. Continuing past pain risks injury, contradicting pain-as-a-guide principles. Doubling after a missed day could strain joints excessively. The daily repetition approach supports gradual improvement, respecting the condition's need for regular, gentle movement to manage stiffness and function, making it the safest, most effective instruction.