grade 9 revision 2

During intense physical activity, which macromolecule stored in the liver is broken down to provide a quick source of glucose?

• A. Protein
• B. Glycogen
• C. Lipid
• D. DNA

Enzymes are specialized macromolecules that speed up reactions. To which macromolecule group do enzymes belong?

• A. Carbohydrates
• B. Lipids
• C. Proteins
• D. Nucleic acids

The body uses triglycerides as long-term energy storage. Which class of macromolecule do triglycerides belong to?

• A. Carbohydrates
• B. Proteins
• C. Lipids
• D. Nucleic acids

The breaking down of carbohydrates into simpler sugars begins in the mouth with the enzyme amylase. Which macromolecule is amylase?

• A. Carbohydrate
• B. Protein
• C. Lipid
• D. Nucleic acid

Athletes often consume carbohydrates before an event to boost energy levels. Why are carbohydrates an efficient source of energy?

• A. They are made up of fatty acids.
• B. They are rapidly broken down into glucose.
• C. They store twice the energy of lipids.
• D. They do not require oxygen for breakdown.

Which macromolecule is primarily responsible for waterproofing surfaces, like those on leaves and feathers?

• A. Proteins
• B. Lipids
• C. Carbohydrates
• D. Nucleic acids

During protein synthesis, RNA carries genetic information to ribosomes. Which type of macromolecule is RNA?

• A. Carbohydrate
• B. Protein
• C. Nucleic acid
• D. Lipid

A scientist observes that an enzyme functions optimally at a pH of 7. When the pH is increased to 10, the enzyme activity drastically reduces. What is the most likely reason?

• A. Increased substrate concentration
• B. Permanent denaturation of the enzyme
• C. Reduced substrate binding to the active site
• D. Complete degradation of the enzyme

A student observes that increasing the temperature from 30°C to 60°C speeds up an enzyme reaction initially, but eventually stops it. What is the most probable reason?

• A. Excess substrate is used up
• B. Increased temperature inactivates the enzyme
• C. Product accumulation inhibits the enzyme
• D. Activation energy is too high for the reaction

An enzyme is exposed to a reversible inhibitor that binds to its active site. What is the best strategy to regain enzyme activity?

• A. Decrease enzyme concentration
• B. Increase substrate concentration
• C. Add more product
• D. Add a non-competitive inhibitor