Short answers, pulled from the story.
Nutrition is the biochemical and physiological process by which an organism uses food and water to support its life. The intake provides nutrients, divided into macronutrients and micronutrients, which are metabolized to create energy and chemical structures.
Macronutrients are the primary substances an organism requires in bulk, while micronutrients are needed only in trace amounts. Organic micronutrients are classified as vitamins, and inorganic micronutrients are classified as minerals.
Carbohydrates contain 4 calories per gram, fats contain 9 calories per gram, and protein contains 4 calories per gram. One Calorie is the amount of energy required to raise 1 kilogram of water by 1 degree Celsius.
Modern nutrition science began in the 1910s as individual micronutrients started to be identified. The first vitamin to be chemically identified was thiamine in 1926, and vitamin C was identified as a protection against scurvy in 1932.
Most plants obtain nutrients from inorganic substances absorbed from the soil and the atmosphere, taking up cations through cation exchange in the soil and carbon dioxide through stomata in their leaves. Because these nutrients provide no energy, green plants gather sunlight in chloroplasts and convert it through photosynthesis.
Malnutrition is nutrient deficiency, the state in which an organism does not have the nutrients it needs. It can be caused by a sudden decrease in nutrient intake, an inability to absorb essential nutrients, or other illnesses and health conditions.
A nutrient cycle is a biogeochemical cycle involving the movement of inorganic matter through soil, organisms, air, or water, where it is exchanged in organic matter. Examples include the water, carbon, nitrogen, phosphorus, and sulfur cycles, and without proper cycling there would be a risk of change in oxygen levels, climate, and ecosystem function.