Water does NOT provide energy (0 kcal). However, it performs many vital functions: Temperature regulation (sweating and evaporation), Nutrient and oxygen transport in blood, Waste elimination (urine and faeces), Lubrication of joints and organs, Medium for biochemical reactions, and Digestion (hydrolysis reactions). The human body can survive weeks without food but only 3-5 days without water.

Protein digestion pathway: Stomach - Pepsin breaks proteins into peptides. Small Intestine - Trypsin, Chymotrypsin (from pancreas) break peptides further. Brush Border - Peptidases convert peptides into amino acids. Absorption - Amino acids are absorbed into blood capillaries of villi. Final products = Amino acids, NOT fatty acids (those are from fat digestion).

Cretinism is a condition in newborns caused by severe iodine deficiency during pregnancy. The mother's inability to produce sufficient thyroid hormones due to iodine deficiency severely impairs fetal brain and neurological development. Affected children have intellectual disability, stunted growth, deaf-mutism, and motor impairment. Prevention: adequate iodine intake during pregnancy via iodized salt.

Copper is an essential trace mineral that: Helps in iron metabolism (ceruloplasmin enzyme converts Fe2+ to Fe3+ for transport), Is needed for melanin synthesis (skin and hair pigmentation), Supports collagen and elastin formation, and Acts as antioxidant (superoxide dismutase enzyme). Copper deficiency can cause anaemia (despite adequate iron), bone defects, neurological problems, and loss of pigmentation. Rich sources: liver, shellfish, nuts, seeds, whole grains.

Glucose is the preferred and primary fuel for the brain. The brain consumes approximately 120g of glucose per day - about 60% of the body's total glucose use at rest. Unlike muscles, the brain cannot use fatty acids directly for energy under normal conditions. During prolonged starvation, the brain adapts to use ketone bodies (from fat breakdown) as an alternative fuel.

A Vegan diet excludes all animal-derived products - meat, poultry, fish, dairy, eggs, and honey. Vegans must plan carefully to avoid deficiencies in Vitamin B12, Vitamin D, Calcium, Iron, Zinc, and Omega-3 fatty acids. A Vegetarian diet excludes meat but may include dairy (lacto-vegetarian) or eggs (ovo-vegetarian) or both (lacto-ovo vegetarian).

Vitamin B6 (Pyridoxine) is essential for: Amino acid metabolism - transamination and deamination reactions, Neurotransmitter synthesis - serotonin, dopamine, GABA, norepinephrine, Haemoglobin synthesis, and Immune function. Deficiency causes peripheral neuropathy (nerve damage), anaemia, skin rashes, and depression. Rich sources: poultry, fish, potatoes, bananas, fortified cereals.

When adequate carbohydrates are available, the body uses them for energy - this spares proteins from being used as fuel and allows them to perform their primary roles (tissue building, enzyme production, etc.). This is called the protein-sparing effect of carbohydrates. When carbohydrate intake is too low, the body breaks down muscle proteins for energy - causing muscle wasting.

Correct nutrient-function pairs: Iron > Haemoglobin formation (oxygen transport), Calcium > Bone and teeth formation and muscle contraction, Iodine > Thyroid hormone synthesis (T3 and T4), Vitamin C > Collagen synthesis and antioxidant, Vitamin K > Blood clotting, Vitamin D > Calcium absorption. Option C is the only correctly matched pair.

Nutrigenomics is the science that studies the interaction between nutrition and genes - specifically how nutrients influence gene expression and how genetic variations affect individual responses to diet. It is the foundation of personalized nutrition - tailoring dietary advice based on an individual's genetic profile. For example, people with certain gene variants metabolize caffeine, fats, or carbohydrates differently.