unit 1..exam

The following graphs illustrate the pepsin enzyme where It works well at pH ranging between (1.5 : 2.5). Which of the following graphs illustrates what happens to the pepsin enzyme, if pH value increased in stomach ? ........

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The reason for the solid nature of fats is the..............

• decrease in hydrogen atoms

• presence of alcohols with three hydroxyl groups

• increase in hydrogen atoms

• presence of monohydric alcohols

Molecules with functional groups COOH and NH₂, can form polymers by a dehydrogenation reaction through the formation of............. bond

• hydrogen

• covalent

• peptide

• ionic

Which of the following biological molecules consist of fatty acids and glycerol?

• Phospholipids only

• Oils and phospholipids

• Oils only

• Waxes only

DNA differs from RNA in that...............

• DNA consists of a single strand and RNA consists of double strands

• DNA contains 4 types of nucleotides and RNA contains 5 types of nucleotides.

• DNA presents inside the nucleus and RNA presents in the nucleus and cytoplasm

• DNA contains uracil base and RNA contains thymine base.

If the normal structure of enzyme is changed, as a result of increasing the temperature , therefore its activity will............

• stop directly

• decrease, till its stopping

• return after decreasing the temperature

• not be affected

In the enzymatic reaction in stomach, the product's amount increases ...........

• by increasing the amount of inhibitors

• by increasing the concentration of hydrogen ion.

• by increasing the substrate

• when the amount of enzyme decreases at the normal body temperature.

A certain enzyme breaks the covalent bonds in DNA molecule, what happens on treating

a nucleotide of DNA with this enzyme ?

• The nitrogenous base wil separate from the nucleotide

• The phosphate group will separate from the nucleotide

• Each of the nitrogenous base and phosphate group will separate from the nucleotide,

• The components of nucleotide will not be affected.

Enzymes

are characterized than the other inorganic catalysts by that they .................

• increase the activation energy

• consist of monomers

• participate in the chemical reaction

• increase the rate of chemical reaction

Which of the following statements is correct about the enzymes that present in

the figure?

• The enzyme no. (1) is less specific than the enzyme no. (3)

• The enzyme no. (1) is high specific than the enzyme no. (3)

• The enzyme no. (2) is less specific than the enzyme no. (3)

• All these enzymes are highly specific