2.5 IB Enzymes #1

What do humans need to digest the lactose in milk?

• a substrate

• an enzyme

• an acid

• a product

Answer explanation

The breaking of the glycosidic bond in lactose by a hydrolysis reaction is facilitated by the enzyme lactase.

Tags

NGSS.MS-LS1-7

What is structure labeled E, F, and G?

• Substrate

• Active site

• Enzyme

• Products

Answer explanation

Remember, enzymes facilitate reactions, they don't actually take part in them themselves.

Enzymes are capable of increasing the rate of a chemical reaction within a living cell. Enzymes accomplish this through which of the following means?

• reducing the number of products

• reducing the activation energy

• increasing the temperature of the cell

• increasing the concentration of reactants

Answer explanation

Lowering activation energy is the sole premise of enzymes, so make sure you understand it.

Tags

NGSS.HS-PS1-5

What is structure D?

• substrate

• active site

• enzyme

• products

Answer explanation

Because enzymes are proteins and proteins have specific shapes, the active site it specific to that enzyme. Shape is EVERYTHING!

Tags

NGSS.HS-LS1-7

Which of the following is NOT true about enzymes?

• enzymes speed up chemical reactions

• enzymes react best at a specific temperature

• enzymes only control ONE type of reaction

• enzymes are made of polysaccharides

Answer explanation

Enzymes are proteins because proteins have specific shapes.

Tags

NGSS.HS-PS1-5

Which of the following can influence the rate of reaction when an enzyme is involved? (4)

• pH

• temperature

• substrate concentration

• enzyme concentration

• reaction vessel

Answer explanation

Because enzymes are proteins they are susceptible to denaturation, so extreme pH and temperature are not good. Also, if you have more enzymes to facilitate the reaction then you will have a faster reaction. The same goes for having more substrate (raw ingredients).

Tags

NGSS.HS-PS1-5

What makes an enzyme substrate specific?

• size

• shape

• name

• location it is found in

Answer explanation

Enzymes are proteins, and shape is everything for proteins.

What is the optimum pH of pepsin which is found in the stomach gastric juice of humans?

• pH 5

• pH 2

• pH 7

• pH 9

Answer explanation

Why? Because there is hydrochloric acid in the stomach to kill bacteria and help facilitate the digestion of food, so any enzyme that has to function in the stomach must do so at an acid pH of 2.

Which of these is NOT true?

• Enzymes can denature (change shape) when the temperature gets too high

• Enzymes can only be used once in a chemical reaction

• Enzymes can denature when the pH changes

• Enzymes speed up chemical reactions

Answer explanation

Enzymes facilitate reactions and do not actually take part in the reaction, hence they can by used over and over again.

Tags

NGSS.HS-PS1-5

What is broken down by the enzyme amylase, which is found in saliva?

• sugar

• starch

• oils

• protein

Answer explanation

Salivary amylase is found in spit and breaks down starch. If you don't believe me, place a starchy food on your tongue and observe how it is digested in just a few minutes - it will start to taste sweet!

Tags

NGSS.MS-PS1-2