Reviewer/Study Guide- Chem of Life

Salivary amylase works best at pH 6.7. Which situation would NOT affect its activity?

• Increasing the pH

• Keeping the pH at 6.7

• Lowering the temperature by 10°C

• Changing the pH to 7.0

Answer explanation

Keeping the pH at 6.7 maintains optimal conditions for salivary amylase activity. Other options, like increasing pH or lowering temperature, would negatively impact its function.

Based on the enzyme graph, what conclusion can be obtained from this graph?

• Pepsin works well at 37°C

• Pancreatic lipase works best at higher pH

• Salivary amylase works well at all pH levels

• Pepsin works better above pH 7

Answer explanation

The graph indicates that pancreatic lipase has optimal activity at higher pH levels, confirming that it works best in alkaline conditions, unlike pepsin, which functions well in acidic environments.

The diagram shows an enzyme fitting with a molecule like a puzzle. The molecule being acted on is a:

• Protein

• Amino acid

• Nucleic acid

• Carbohydrate

Answer explanation

The enzyme fits with a molecule like a puzzle, indicating a specific interaction. In this case, the molecule being acted on is a protein, as enzymes typically catalyze reactions involving proteins.

What do enzymes do in a chemical reaction?

• Raise the temperature

• Require more energy

• Make a different product

• Lower the activation energy

Answer explanation

Enzymes act as catalysts in chemical reactions by lowering the activation energy required for the reaction to occur. This allows reactions to proceed more quickly and efficiently without changing the products formed.

Lactase works best between 21–49°C and pH 2–7. What happens if conditions go outside this range?

• Lactase reverses the reaction

• Lactose breaks apart on its own

• Lactase cannot break down lactose

• Reaction happens the same way

Answer explanation

Lactase is an enzyme that functions optimally within specific temperature and pH ranges. If conditions exceed these limits, lactase's structure can be altered, preventing it from effectively breaking down lactose.

Marissa studies a reaction that needs an enzyme. What is the enzyme’s role?

• Speed up the reaction

• Change the products

• Change the reactants

• Change the energy released

Answer explanation

The enzyme's primary role is to speed up the reaction by lowering the activation energy required, allowing the reaction to occur more quickly without altering the reactants or products.

How do enzymes act as catalysts in living things?

• They increase activation energy

• They slow reactions

• They lower activation energy, speeding reactions

• They are permanently changed

Answer explanation

Enzymes act as catalysts by lowering the activation energy required for reactions, which speeds up the rate of those reactions in living organisms. This is essential for maintaining life processes efficiently.

Without enzymes, how would cell reactions be affected?

• Reactions would be faster

• Reactions would be too slow for life

• Reactions would not need energy

• Reactions would stop forever

Answer explanation

Without enzymes, biochemical reactions would occur at a much slower rate, making it impossible for essential life processes to take place in a timely manner. Thus, reactions would be too slow for life.

Why is the enzyme-substrate complex important?

• It changes the enzyme permanently

• It makes reactions more efficient

• It raises the cell’s temperature

• It stops reactions

Answer explanation

The enzyme-substrate complex is crucial because it increases the efficiency of biochemical reactions by lowering the activation energy required, allowing reactions to occur more quickly and effectively.

What would most likely happen to an enzyme if the temperature is increased too much?

• It would work faster

• It would change into a substrate

• It would become denatured and stop working

• It would produce more products

Answer explanation

Increasing the temperature too much can cause an enzyme to denature, meaning it loses its specific shape and functionality, leading to a stop in its activity. Thus, the correct answer is that it would become denatured and stop working.