Q.Given below are two statements labelled Assertion (A) and Reason (R). Assertion (A): The Basal Metabolic Rate (BMR) is the number of calories needed to maintain body function at resting condition. Reason (R): A person who does not engage in any work, still requires energy for the functioning of their internal organs. In the context of the above two statements, which of the following option is correct? (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.

The concept of Basal Metabolic Rate sits at the heart of understanding human energy needs. Think of your body as a machine that never truly switches off — even when you're lying perfectly still, asleep or resting, your heart continues to beat, your lungs draw breath, your kidneys filter blood, your brain processes signals, and countless cells carry out their maintenance work. All of this invisible activity demands energy, measured in calories. That baseline energy requirement, stripped of any physical activity or digestion, is what we call BMR.

The key word here is "basal," meaning fundamental or base-level. BMR is measured under very specific conditions: the person must be awake but completely at rest, in a neutral temperature environment (so the body isn't expending extra energy to warm or cool itself), and in a post-absorptive state — meaning at least 12 hours after the last meal, so no energy is being used for digestion. These strict conditions ensure we're measuring only the energy needed for essential physiological functions.

Let's examine why the other options miss the mark:

• Exercise and movement (options A and B) immediately disqualify themselves because any physical activity — whether vigorous exercise or simple movement — adds energy expenditure above the basal rate. BMR specifically excludes these activities.
• High speed function (option C) is a misleading phrase. The body's vital functions operate at their normal, steady pace during rest, not at any accelerated "high speed." Increased metabolic rate during stress or activity is something different entirely. …

The concept of Basal Metabolic Rate sits at the heart of understanding human energy requirements. Think of your body as a city that never sleeps: even when you are lying perfectly still, doing absolutely nothing, a vast network of processes continues without pause. Your heart pumps blood, your lungs draw breath, your kidneys filter waste, your brain coordinates signals, your liver processes nutrients, and every cell maintains its delicate internal environment. All of this invisible work demands fuel.

Assertion (A) states that BMR is the number of calories needed to maintain body function at resting condition. This is precisely correct. Basal Metabolic Rate represents the minimum energy expenditure required to keep you alive when you are at complete rest — typically measured after a full night's sleep, in a fasting state, in a thermoneutral environment. It accounts for the energy your body burns simply to exist, before you add any physical activity, digestion, or other demands on top.

Reason (R) explains that a person who does not engage in any work still requires energy for the functioning of their internal organs. This is equally true and gets to the biological reality behind BMR. Even if you were to lie motionless for an entire day, your body would still consume a substantial number of calories. The heart alone beats roughly 100,000 times a day; the brain, though only about 2% of body weight, consumes around 20% of resting energy; the liver, kidneys, and other organs all carry out energy-intensive biochemical processes continuously. …

Concept understanding — what "physiological parameters" means

Males and females share the same body systems, but the systems run at slightly different set-points because of differences in body composition and hormones (chiefly testosterone in males and oestrogen in females). These are averages that describe general trends, not fixed rules about any one person.

Difference 1 — Basal Metabolic Rate (BMR)

BMR is the energy the body uses at complete rest just to stay alive — breathing, circulating blood, and maintaining temperature. Males typically have a higher BMR than females of the same age and weight. The reason is body composition: males carry a greater proportion of lean muscle mass, and muscle tissue burns more energy at rest than fat tissue. This is why energy (calorie) requirements are usually higher for males.

Difference 2 — Red blood cells and haemoglobin …