Zoology MCQs for NEET — Practice Questions with Answers

(c) Sucrose, glucose and fructose, all the three sugars are found in plants. Sucrose is the commercial sugar which is obtained from sugarcane. Glucose is the main respiratory substrate in plants and animals. Fructose can also function similarly. Moreover, fructose is also the common fruit sugar.

Lactose or milk sugar is found naturally in milk. It is reducing sugar which is formed in the mammary glands of mammal through condensation of two hexose molecules.

(a) The reason for quick detoriation of jute fibres is its high cellulose content. The cell walls of jute contains a major portion of cellulose and low lignin levels. Microorganisms find it hard to decompose lignin but as cellulose is used by them as food, decomposition of jute becomes easy.

(c) Water is the most abundant chemical compound in living organism. In a cell, water occupies 70-90% of the cellular mass. So, in 50 gm of living tissue 35-45 gm of water would be present.

(d) Trace elements or microelements (e.g. iron, iodine, zinc, manganese, cobalt, copper, molybdenum, etc.) are required in very samll amounts to our body.

(a)

(b) Homopolysaccharides or homoglycans are those complex carbohydrates which are formed by polymerization of only one type of monosaccharide monomers. For example, starch, glycogen, inulin, cellulose, chitin, etc.

Agar, pectin, hyaluronic acid, heparin, etc., are heteropolysaccharides.

(d) Secondary metabolites are derivates of primary metabolites which have no direct function in growth and development of plants. These compounds are accessory rather than central to the functioning, eg., arbin, cellulose, gums, diterpenes, carotenoids, curcumin, rubber etc. Arginine, tyrosine, glycine, serine and phenylalanine are amino acids, which are primary metabolites.

(a) DNA and RNA are nucleic acids which are found in living systems. DNA is a long polymer of deoxyribonucleotides and RNA is a long polymer of ribonucleotides. A nucleotide has 3 components - a nitrogenous base, a pentose sugar and a phosphate group.

(b) Non-essential amino acids are those amino acids which can be synthesized by human body from raw materials. Glycine, serine, proline, glutamic acid all are non-essential amino acids.

(a) Adenine (A), guanine(G), cytosine (C), thymine (T) and uracil (U) are all nitrogenous bases, whereas cytidine is a nucleoside i.e, a combination of a nitrogenous base (cytosine) with a pentose sugar (ribose).