Answer: Option D. -> None of the above
:
D
A biomolecule is any molecule that is produced by living organisms, including larger macromolecules such as proteins, carbohydrates, lipids, and nucleic acids; as well as smaller molecules such as primary metabolites, secondary metabolites, and other natural products. A generalised term for this class of materials, is biological materials.
The bacteria in our gut produce methane as a byproduct of digestion. Ammonia is produced as a byproduct of protein metabolism and HCl is produced by our very own stomachs to digest everything we eat, making all the three, biomolecules.

Answer: Option B. -> Products and enzymes molecules
:
B
If there are 10 molecules of enzymes that can act on 20 molecules of the substrate and convert it into product in 5 minutes. In the next 5 minutes the remaining 5 substrates will also be converted into product, therefore there will be no substrate present in the mixture at the end of 10 minutes. Therefore all that the test tube will contain at the end of 10 minutes is the enzymes and the products. The enzymes are not used up in the process of forming products.

Answer: Option C. -> R group
:
C
Amino acids are the basic constituents of proteins and the molecule is made up of an amino group and a carboxyl group attached to a central carbon atom called the alpha carbon. The alpha carbon also binds to an R-group, which differs from one amino acid to another and confers the amino acid with its acidic, basic or neutral properties.

Answer: Option A. -> Glucose monomers forming unbranched chains with only beta 1,4 linkages
:
A

Cellulose is a polymer of beta glucose units in an unbranched 1-4 glycosidic linkage.

Answer: Option B. -> Lipogenesis
:
B
The process of synthesis of lipids in the human body is called lipogenesis. Lipo=lipids and genesis=to generate. Lipolysis and lipogenolysis are break down of lipids, that is breakdown of triglycerides to glycerol and fatty acids.

Answer: Option B. -> B and C
:
B
Amino acids can form zwitter ions, that isa molecule or ion having separate positively and negatively charged groups. Amino acids form due to the presence of an amine group, that can ionize to form ${NH}_3^{+}$ and a carboxyl group that can form ${COO}^{-}$. When they are in the zwitter ion form, they do not migrate in an electric field and they precipitate out of the solution. Therefore amino acids are least soluble at a pH when they exist in the zwitter ion form, that is when the concentration of anions and cations are equal.
The other two statements are true:
The amine group of amino acids reacts with ninhydrin reagent to give a purple colour complex.
And amino acids react with nitrous acid releasing$N_2$.

Answer: Option C. -> Phosphodiester bonds
:
C
The phosphodiester bond is a condensation reaction, leading to release of a water molecule as shown here

Answer: Option B. -> 24 g
:
B
Per gram of carbohydrates contain 4 calories. Therefore we can obtain 96 calories by consuming 96/4 = 24 grams of carbohydrates.