Question

multiple choice question
what must occur before a carbohydrate like sucrose is used in cellular respiration?
o an enzyme must break it down to glucose and fructose.
o oxygen levels must be low from increased metabolism.
o glucose and fructose must be bonded together.
o sucrose must first be converted into a disaccharide.

Explanation:

Step1: Analyze each option

• Sucrose is a disaccharide. It cannot be directly used in cellular respiration. It needs to be broken down into monosaccharides (glucose and fructose) first. So the option “Sucrose must first be converted into a disaccharide” is wrong.
• Glucose and fructose are monosaccharides. They are the products of sucrose breakdown, not something that needs to be bonded together for sucrose to be used in cellular respiration. So the option “Glucose and fructose must be bonded together” is wrong.
• Cellular respiration can occur in both aerobic (with oxygen) and anaerobic (without oxygen) conditions. Low oxygen levels are not a prerequisite for using sucrose (after breakdown) in cellular respiration. So the option “Oxygen levels must be low from increased metabolism” is wrong.
• Enzymes are biological catalysts. Sucrose (a disaccharide) needs to be broken down into glucose and fructose (monosaccharides) by an enzyme (such as sucrase) before it can be used in cellular respiration (e.g., glycolysis where glucose is the starting molecule in the first step of aerobic and anaerobic cellular respiration pathways in most cases).

Answer:

An enzyme must break it down to glucose and fructose.