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

• transient but stable

• permanent but unstable

• transient and unstable

• permanent and stable

A phosphoglyceride is always made up of

• only a saturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached

• only an unsaturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached

• a saturated or unsaturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached

• a saturated or unsaturated fatty acid esterified to a phosphate group, which is also attached to a glycerol molecule

Pigment-containing memberanous extensions in some cyanobacteria are

• heterocysts

• basal bodies

• pneumatophores

• chromatophores

A major site for synthesis of lipids is

• RER

• SER

• symplast

• nucleoplasm

The complex formed by a pair of synapsed homologous chromosomes is called

• equatorial plate

• kinetochore

• bivalent

• axoneme

The three boxes in this diagram represent the three major biosynthetic pathways in aerobic respiration. Arrows represent net reactants or products

Arrows numbered 4, 8 and 12 can all be 

• NADH

• ATP

• H₂O

• FAD⁺ or FADH₂

The most abundant intracellular cation is

• Na⁺

• Ca²⁺

• H⁺

• K⁺

During seed germination its stored food is mobilised by

• ethylene

• cytokinin

• ABA

• gibberellin

Which of the following criteria does not pertain to facilitated transport?

• Requirement of special membrane proteins

• High selectivity

• Transport saturation

• Uphill transport

20.

The first stable product of fixation of atmospheric nitrogen in leguminous plants is

• NO₂^-

• ammonia

• NO₃^-

• glutamate