The pyrenoids are made up of

1.	Proteinaceous centre and starchy sheath
2.	Core of protein surrounded by fatty sheath
3.	Core of starch surrounded by sheath of protein
4.	Core of nucleic acid surrounded by protein sheath

Macromolecule chitin is                                                   [2013]

One turn of the helix in a B-form DNA is approximately

1. 0.34 nm

2. 3.4 nm

3. 2 nm

4. 20 nm

Which of the following statements regarding enzyme inhibition is correct?

If DNA percentage of thymine is 20. What is the percentage of guanine?                         [2002]

1. 20%

2. 40%

3. 30%

4. 60%

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

Given below is the diagrammatic representation of one of the categories of the small molecular weight organic compounds in the living tissues. Identify the category shown and the one blank component X in it.

      Category                             Component

1. Cholesterol                            Guanine

2. Amino acid                            ${\mathrm{NH}}_2$

3. Nucleotide                             Adenine

4. Nucleoside                            Uracil

Cytochrome is                          [2001]

1. Metallo flavoproteins

2. Fe containing porphyrin pigment

3. Glycoprotein

4. Lipid 

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