Nutrients - Vitamins, Carbohydrates, and Proteins

Vitamin $B _1$ is mostly found in meat, fish, and poultry products

The source of pyridoxine are cereals, meat and yeast.

Vitamin $D$ is required for the normal development of bones and teeth.
It regulates the adsorption of calcium and phosphate from intestine and promotes formation of bone.
It helps in deposition of calcium and phosphate in bones.

Vitamin $D$ is called calciferol or ergocalciferol. lt is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, and in mineralization of bone.
Vitamin $D$ in human body exist in two form :
(I) Vitamin $D _2$, also called as ergocalciferol.
(II) Vitamin $D _3$, also called as calciferol or cholecalciferol. 

Cyanocobalamin is rich in liver of pig. Cyanocobalamin is also called as vitamin $B _{12}$. It is used to prevent and treat low blood levels of this vitamin. It is important to maintain metabolism blood cells, and nerves. Some common sources of vitamin $B _{12}$ are liver, kidney, chicken, pork, beef, fish, eggs and dairy products.

The human body does not produce Vitamins. They have been produced as commodity chemicals and made widely available as inexpensive semisynthetic and synthetic-source multivitamin dietary and food supplements and additives

The non-protein component in enzymes, which is necessary for its biological activity, is called coenzyme. The activity of an enzyme depends, at the minimum, on a specific protein chain. In many cases, the enzyme consists of the protein and a combination of one or more non-protein parts called coenzymes. Coenzymes can be either inorganic or organic compounds. They include NADH, NADPH and ATP. These molecules transfer chemical groups between enzymes.

The vitamin essential for synthesis of lipids is biotin.
Biotin is required for carboxylase enzymes that are important in the metabolism of fatty acids and amino acids. Thus it acts like a coenzyme in the metabolism of fatty acids (types of molecules found in fats and oils).

The source of folic acid is spinach leaf. It is also found in asparagus, lettuce, chick peas, sprouts, beets, broccoli, corn, green peas, oranges, orange juice, legumes and green leafy vegetables.

Vitamins $B$ and $C$ are present in much smaller amounts in cells. These vitamins are micronutrients. These are required in very minute amounts. Together, they are extremely important for the normal functioning of the body. Their main function is to enable the many chemical reactions to occur in the body.

All vitamins are synthesized by plants. They cannot be synthesized by human beings. Hence, they must be supplied through diet.

The vitamin which maintain the redox potentials of cells is ascorbic acid. It is also called as vitamin $C$. It is the component of plasma and extracellular fluids and so can control lipid peroxidationof cellular membranes, thus maintaining the redox integrity of cells. Vitamin $C$ along with zinc, iron and copper enhances the immunity of the body. It has therapeutic potential against neuro degenerative disease. It is a potent antioxidant and this activity is transition metal-dependent due to its reduction potential. In the absence of enzymes, vitamin $C$ reduces free $Fe^{+3}$ and $Cu^{+2}$ to reactive forms $Fe^{+2}$ and $Cu^{+1}$, which then participate in the radical-producing Fenton reaction.

Vitamin K is a naphthaquinone derivative. It contains isoprene units.
It is also called as "anti-haemorrhagic" vitamin.

Given statement is false because Vitamin D is synthesised in skin cells in  presence of sunlight.

Vitamin E is also called Tocopherol. It is a reproductive vitamin. It is also called anti-sterility vitamin as its deficiency leads to sterility.

Cyanocobalamine is vitamin $B _{12}$. It is manufactured by bacteria and can only be found naturally in animal products. Its main sources are liver of ox, fish, crab, milk, cheese, etc. Thus, it is not obtained from plants.

Liver is not the source of Vitamin - $B _1$

Our mineral needs are met from food. Minerals also help your body function. Some minerals, like iodine and fluoride, are only needed in very small quantities. Others, such as calcium, magnesium, and potassium, are needed in larger amounts. As with vitamins, if you eat a varied diet, you will probably get enough of most minerals.

Cereals are staple food and are important source of energy,carbohydrates,protein and fibre. Examples of cereals include wheat, oats,quinoa,maize,sorghum etc.
So the correct answer is 'Carbohydrates'

Carbohydrates are more suitable for the production of energy in the body then proteins and fats. Carbohydrate are also stored in the body cells as glycogen and are used for the production of energy whenever required.

Carbohydrate digestion begins in the mouth with the action of salivary amylase on starch.

The energy content is approximately 4 kcal/g for carbohydrates, 4 kcal/g for proteins, and 9 kcal/g for fats. The ratio is roughly 1:1:2.

Acetyl CoA is the central intermediate in metabolism, produced from both the breakdown of carbohydrates (via pyruvate) and fatty acids (via beta-oxidation).

Carbohydrate is the major source of energy without which one cannot live. It is because carbohydrate is broken down to form instant energy in the form of glucose which can be converted into ATP and thus used for the regular functioning of the cell. Other forms of energy like proteins, vitamins, and minerals are the extra components that are not directly involved in the formation of energy.

Energy storage molecules are those molecules which store energy in the form of covalent chemical bonds. Some molecules like glycogen (carbohydrate) and triglycerides (lipids) are synthesized by the cells and they are stored for the later release of energy. So, the correct answer is "both lipids and carbohydrates".

Proteins are the polymers of amino acids held together by peptide bonds. Carbohydrates are polyhydroxy aldehyde or ketones or their derivatives. Nucleic acids are polymers of nucleotides held together by phosphodiester bonds. Lipids are the chemically diverse group and mostly have long hydrocarbon chain. Thus, the correct answer is B.

Amylase is peptide hormone and consists of amino acids as monomer subunit. Glycogen is homopolysaccharide of D-glucose while lipids having attached phosphate groups are called as phospholipids. Polysaccharides are polymers of simple sugars (single polyhydroxy aldehyde or ketone unit). Ribonucleic acid is a polymer of ribonucleotide monomers. Thus, the correct answer is A.