Which is wrong about nucleic acids?                                 [1993]

1. DNA is single stranded in some viruses

2. RNA is double stranded occasionally

3. Length of one helix is 45 Å in B-DNA

4. One turn of Z-DNA has 12 bases

Cellulose, the most important constituent of plant cell wall is made of                     [1998]

1. Unbranched chain of glucose molecules linked by $\mathrm{\alpha }$ 1, 4-glycosidic bond

2. Branched chain of glucose molecules linked by $\mathrm{\beta }$ 1, 4-glycosidic bond in straight chain and $\mathrm{\alpha }$, 1, 6-glycosidic bond at the site of branching

3. Unbranched chain of glucose molecules linked by $\mathrm{\beta }$ 1, 4-glycosidic bond

4. Branched chain of glucose molecules linked by $\mathrm{\alpha }$ 1, 6-glycosidic bond at the site of branching

The most abundant element present in plants is                               [2004]

1. Carbon

2. Nitrogen

3. Manganese

4. Iron

Transition state structure of the substrate formed during an enzymatic reaction is

1. Transient but stable

2. Permanent but unstable

3. Transient but unstable

4. Permanent and stable

Which one of the following is a non-reducing carbohydrate?                                [2014]

1. Maltose

2. Sucrose

3. Lactose

4. Ribose-5-phosphate

In the DNA molecule

1. The total amount of purine nucleotides and pyrimidine nucleotides is not always equal

2. There are two strands which run parallel in 5'$\to$3' direction

3. The proportion of adenine in relation to thymine varies with the organism

4. There are two strands which run antiparallel one in 5'$\to$3' direction and other in 3'$\to$5' direction 

The major portion of the dry weight of plants comprises of                  [2003]

1. Carbon, nitrogen and sulphur

2. Carbon, nitrogen and oxygen

3. Nitrogen, phosphorous and potassium

4. Calcium, magnesium and sulphur

Select the option which is not correct with respect to enzyme action.

1. Substrate binds with enzyme as its active site

2. Addition of lot of succinate does not reverse the inhibition of succinic dehydogenase by malonate.

3. A non-competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate

4. Malonate is a competitive inhibitor of succinic dehydrogenase

Two free ribonucleotide units are interlinked with

1. Peptide bond

2. Covalent bond

3. Hydrogen bond

4. Phosphodiester bond

Genes are packaged into a bacterial chromosome by                           [1997]

1. Histones

2. Basic proteins

3. Acidic proteins

4. Actin