Pakistan MCQs

DNA is a polymer made of nucleotides.
Each nucleotide contains a sugar, phosphate, and nitrogenous base.

DNA contains the five-carbon sugar deoxyribose.
RNA contains ribose instead.

Purines have a double-ring structure.
Adenine and guanine occur in both DNA and RNA.

DNA pyrimidines have single-ring structures.
They are cytosine and thymine.

The active site has a shape and chemistry suited to its substrate.
Binding promotes the transition state.

Substrates bind to active sites.
They are converted into products during the reaction.

Warming increases molecular collisions up to an optimum.
Excess heat disrupts enzyme structure.

PH alters ionization of amino-acid side chains.
Extreme pH can reduce activity or denature enzymes.

Competitive inhibitors resemble or obstruct the substrate.
Their effect can often be reduced by increasing substrate concentration.

Plants store glucose mainly as starch.
It consists of amylose and amylopectin.

Noncompetitive binding changes enzyme shape or function.
Adding more substrate does not fully overcome it.

Cellulose consists of beta-glucose units.
Humans lack enzymes to digest its beta linkages.