Enzyme College Biology Practice

A __________ is a chemical involved in, but not changed by, a chemical reaction.

• peptide

• enzyme

• catalyst

• steroid

Enzymes act as catalysts for numerous and complex biochemical reactions that take place in animals, plants, and microorganisms. For instance, the enzyme amylase converts starch into __________.

• salt

• carbon

• protein

• sugar

Answer explanation

These proteins are efficient and specific —- that is, they accelerate the rate of one kind of chemical reaction of one type of compound, and they do so in a far more efficient manner than man-made catalysts.

__________ energy (Ea) is the minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport.

• Activation

• Reserve

• Acceleration

• Electrical

Answer explanation

Many enzymes function by lowering the activation energy of reactions.

Each enzyme is able to promote only one type of chemical reaction. The specific compounds on which the enzyme acts are called __________.

• substrates

• organelles

• mitochondrions

• peroxisomes

Answer explanation

The functioning of the enzyme is determined by its own shape as a protein. There are over 2,000 known enzymes, each of which is involved with one specific chemical reaction

The arrangement of molecules on the enzyme produces an area known as the __________ within which the specific substrate(s) will "fit".

• active site

• endomembrane

• autophagy

• active hydrolytic

Answer explanation

E.g. the enzyme peptidase (which breaks peptide bonds in proteins) will not work on starch (which is broken down by human-produced amylase in the mouth).

A simple human muscle contraction involves a complex sequence of reactions called the __________.

• biosynthetic pathway

• metabolic rate

• properdin pathway

• metabolic pathway

Answer explanation

It takes a series of reactions to result in one muscle contraction. The product of one step in a metabolic pathway serves as the substrate for the succeeding step in the pathway

Tags

NGSS.HS-LS2-3

NGSS.HS-LS2-5

The idea of a fit between substrate and enzyme, called the key-lock hypothesis, was proposed by a German chemist, __________, in 1899 and explains one of the most important features of enzymes, their specificity.

• Kurt Alder

• Otto Diels

• Emil Fischer

• Daniel Koshland

Answer explanation

In most of the enzymes studied thus far, a cleft, or indentation, into which the substrate fits, is found at the active site.

An improvement on the "__________" theory, the induced-fit hypothesis suggests that the binding of the substrate to the enzyme alters the structure of the enzyme

• panspermia

• nucleic acid

• key-lock

• particulate

Answer explanation

This concept has been likened to the fit of a hand in a glove, the hand (substrate) inducing a change in the shape of the glove (enzyme)

__________ are non-proteins attached to the enzyme essential for catalytic activity.

• Plastids

• Cofactors

• Protists

• Micronutrients

Answer explanation

Ions such as K+ and Ca+2 are cofactors.

__________ increase speeds up enzyme mediated reactions, but only to a point.

• Pressure

• Temperature

• Toxin

• Oxygen

Answer explanation

When heated too much, enzymes (since they are proteins dependent on their shape) become denatured. When the temperature drops, the enzyme regains its shape.