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Glucose and mannose are epimers.

1. Reducing sugars: 

Those carbonhydrates which contain free aldehyde or ketonic group and reduces Fehling’s solution and Tollen’s reagent are called reducing sugars. All monosacehaides whether aldose or ketone are reducing sugars.

2. Non – reducing sugars: 

Cabohydrates which do not reduce Tollen’s reagent and Fehling’s solution are called non – reducing sugars. Example Sucrose. They do not have free aldehyde group.

1. Proteins are classified based on their structure into two major types. They are fibrous protein and glubular protein. 

2. Fibrous proteins are linear molecules similar to fibres. They are generally insoluble in water and are held together by disulphide bridges and weak inter molecular hydrogen bonds. These proteins often used as structural proteins. Example, Keratin, Collagen. 

3. Globular proteins have an overall spherical shape. The poly peptide chain is folded into a spherical shape. These proteins are usually soluble in water and have many functions including catalysis.

On the basis of structure, proteins are classified into three categories: 

1. Simple proteins: 

a. Simple proteins on hydrolysis yield only amino acids. 

b. These are soluble in one or more solvents.

c. Simple proteins may be soluble in water. 

d. Histones of nucleoproteins are soluble in water. 

e. Globular molecules of histones are not coagulated by heat. 

f. Albumins are also soluble in water but they get coagulated on heating. 

g. Albumins are widely distributed e.g. egg albumin, serum albumin and legumelin of pulses are albumins. 

Importance: They are involved in structural components; they also act as a storage kind of protein. 

Some are associated with nucleic acids in nucleoproteins of cell.

2. Conjugated proteins: 

a. Conjugated proteins consist of a simple protein united with some non-protein substance. 

b. The non-protein group is called prosthetic group e.g. haemoglobin.

c. Globin is the protein and the iron containing pigment haem is the prosthetic group. 

d. Similarly, nucleoproteins have nucleic acids. 

e. Proteins are classified as glycoproteins and mucoproteins. 

f. Mucoproteins are carbohydrate-protein complexes e.g. mucin of saliva and heparin of blood. 

g. Lipoproteins are lipid-protein complexes e.g. conjugate protein found in brain, plasma membrane, milk etc. 

Importance: They are involved in structural components of cell membranes and organelles. 

They also act as a transporter. 

Some conjugated proteins are important in electron transport chain in respiration. 

3. Derived proteins: 

a. These proteins are not found in nature as such. 

b. These proteins are derived from native protein molecules on hydrolysis. 

c. Metaproteins, peptones are derived proteins. 

Importance: They act as a precursor for many molecules which are essential for life.

Derived Lipids: 

a. They are composed of fused hydrocarbon rings (steroid nucleus) and a long hydrocarbon side chain. 

b. One of the most common sterols is cholesterol. 

Biological significance: 

a. It is widely distributed in all cells of the animal body, but particularly in nervous tissue. 

b. Cholesterol exists either free or as cholesterol ester. 

c. Adrenocorticoids, sex hormones (progesterone, testosterone) and vitamin D are synthesized from cholesterol.

d. Cholesterol is not found in plants. 

e. Sterols exist as phytosterols in plants. 

f. Yam Plant (Dioscorea) produces a steroid compound called diosgenin. It is used in the manufacture of antifertility pills, i.e. birth control pills.

(b) Holoenzyme

According to Chargaff’s rule, the hydrogen bonding between Adenine and Thymine is 2.

Shape to the ribosomes is provided by rRNA.

Correct Answer is : (b) tRNA

Correct Answer is: (c) Mycoplasma

Polysaccharides are also called as Glycans. They are made of hundreds of monosaccharide units.

The number of substrate molecules changed per minute by a molecule of enzyme is called turn over number.

Action of amylase stops in stomach as it cannot act in an acidic medium.