Nutrition in Plants and Animals - 2

Rice is a cereal grain and one of the primary sources of carbohydrates globally. Meat is primarily protein, carrots provide vitamins and fiber, and groundnuts (peanuts) are mainly fats and proteins. For sufficient carbohydrates, grains like rice are the best choice.

Macronutrients are nutrients required in large amounts: carbohydrates, proteins, and fats. Minerals like Ca (calcium), P (phosphorus), and K (potassium) are macronutrients. Mn (manganese) is a micronutrient/trace mineral required only in small amounts, making it the correct answer.

Casein is the primary protein found in milk, constituting about 80% of milk's protein content. Meat is rich in myofibrillar proteins, egg contains albumin, and rice is primarily a carbohydrate source with minimal complete protein. Milk is the best source of casein.

A balanced diet provides all essential nutrients in proper proportions. Option B correctly states this fundamental characteristic. A diet rich only in proteins (C) or fats (D) would be unbalanced, while inadequate (A) contradicts the definition of balanced.

Dentine forms the majority of tooth structure, lying beneath the enamel and surrounding the pulp cavity. While enamel is the hardest outer covering, it's relatively thin. The pulp cavity contains soft tissue and nerves, while 'root' refers to the portion embedded in gum, not a tissue type.

Glucose is the primary energy source for cellular respiration, producing ATP through glycolysis and oxidative phosphorylation. While fats can provide energy, they're primarily storage molecules. Proteins are mainly used for building and repairing tissues, and fructose requires conversion to glucose before cellular use.

A nutritionally adequate diet requires all major nutrient groups: proteins for tissue building and repair, vitamins and minerals for metabolic functions, and carbohydrates and fats for energy. No single nutrient group can fulfill all dietary needs.

Sulphur is a critical component of two proteinogenic amino acids: cysteine and methionine. These sulphur-containing amino acids are essential for protein synthesis. While sodium, iron, and potassium are vital minerals, they are not structural components of amino acids themselves.

Molars are large, flat teeth located at the back of the mouth designed for grinding and crushing food. Canines are pointed for tearing, incisors are sharp for cutting, and 'milk teeth' refers to baby teeth, not a tooth type.

Phloem is the vascular tissue responsible for transporting sugars and organic nutrients (photosynthates) from leaves to storage organs and growing parts. Xylem transports water and minerals upward. Tracheids are xylem cells for water transport, and collenchyma provides structural support.

Cell membranes are primarily composed of phospholipids (lipid bilayer) and membrane proteins. Proteins and lipids work together for membrane structure and function. While carbohydrates are present as glycoproteins/glycolipids, and fats/minerals have roles, proteins and lipids are the chief structural components.

Holozoic nutrition involves ingestion of solid organic food, like Amoeba engulfing food particles via phagocytosis. Amoeba cannot make its own food (not autotrophic). While it is heterotrophic (obtains food from external sources), 'holozoic' more specifically describes its mode of ingesting particulate matter.

Saprophytes are organisms that obtain nutrition from dead and decaying organic matter, secreting enzymes to break down complex molecules externally. Parasites feed on living hosts. Autotrophic organisms produce their own food.

Rhodopsin (visual purple) requires vitamin A for synthesis. Carrots are rich in beta-carotene, which the body converts to vitamin A. Vitamin A deficiency causes night blindness due to insufficient rhodopsin. Tomatoes, radish, and guavas don't provide significant vitamin A.

Calcium, phosphorus, sodium, and magnesium are macrominerals required in substantial amounts (hundreds of milligrams to grams daily). Calcium and phosphorus are critical for bones, sodium for fluid balance, and magnesium for enzyme function. Options A, B, and D include trace minerals (molybdenum, zinc, manganese, cobalt, copper) which are needed in much smaller quantities.

Carbohydrates are the primary energy source in most human diets, typically comprising 45-65% of total caloric intake. They are the body's preferred fuel for energy production. Proteins are needed for tissue repair and growth, lipids (fats) provide concentrated energy and cell membrane structure, while minerals are required in smaller amounts for various metabolic functions as micronutrients.

Human saliva is slightly acidic to neutral, with pH typically ranging from 6.2 to 7.6. The range of 6.7 to 7.2 represents the normal physiological variation in healthy individuals. Options A, B, and C are incorrect because they indicate alkaline ranges that are not found in normal human saliva.

Legumes like gram (chickpea) form symbiotic relationships with Rhizobium bacteria, creating nitrogen-fixing nodules on their roots. These bacteria convert atmospheric nitrogen into ammonia that plants can use. Mustard, rice, and cotton are non-leguminous plants and do not form such nitrogen-fixing nodules.

Starvation occurs when caloric intake is insufficient to meet energy expenditure, forcing the body to use stored energy reserves. This negative energy balance leads to weight loss and metabolic changes. Options A, B, and D are incorrect - starvation is not about stomach fullness, food storage, or meeting energy needs (which would be adequate nutrition).