AP Bio Free Response Question Answers for Blood Sugar Homeostasis

👋 Welcome to the AP Bio Unit 4 FRQ (Blood Sugar Homeostasis) Answers. Have your responses handy as you go through the rubrics to see how you did!

⏱ Remember, the AP Biology exam has 6 free-response questions, and you will be given 90 minutes to complete the FRQ section. (This means you should give yourself ~15 minutes to go through each practice FRQ.)

Setup

Blood sugar in humans is regulated through a series of homeostatic mechanisms to maintain levels at a consistent, healthy level. When sugar is consumed and blood sugar rises, different metabolic pathways are triggered to return the levels to normal. When blood sugar levels fall too low, other metabolic pathways are triggered to return the levels to normal.

A person with diabetes mellitus (a.k.a., Type II diabetes) experiences disruptions to these feedback loops when their blood sugar rises uncontrollably, and the body is unable to lower it on its own. A person with juvenile diabetes (a.k.a., Type I diabetes) also results in uncontrollable blood sugar levels, but due to a lack of a hormone that promotes blood glucose uptake in the liver to lower blood sugar levels. 

Questions with Answers & Rubric

(a) Identify the hormone that is nonfunctional or nonexistent in Type I diabetes patients.

🏆 1pt: Identify

• Insulin

📄 Additional Resources

• Homeostasis & Feedback Loops

(b) Describe the feedback loop utilized to return blood sugar levels to normal after a person consumes a food containing glucose, such as fruit, white rice or a piece of candy.

🏆 2pts: Describe - A negative feedback loop forces a system to try and return to normal by stopping something that is pushing the organism out of homeostasis

📄 Additional Resources

• Homeostasis & Feedback Loops

(c) Construct a graph that demonstrates the amounts of glucose and the hormone identified in Part A in a healthy person’s blood after consuming a food containing glucose, such as fruit, white rice, or a piece of candy.

🏆 3pts: Construct a graph

• This should include equally spaced measurements, properly plotted data points, and correctly labeled x-y axes with independent and dependent variables.

(d) Hormone receptors on the liver trigger a signal transduction pathway that results in the uptake of glucose from the bloodstream, lowering blood sugar levels to safe amounts. This is because glucose is able to enter liver cells through transport proteins called GLUT, which open and close on command when triggered by the hormone receptors. Identify the type of cell transport that the GLUT protein uses.

🏆 1pt: Identify

• Facilitated diffusion

📄 Additional Resources

• Membrane Permeability (from Unit 2)

• Facilitated Diffusion (from Unit 2)

Next Steps

• 🧠 Want to continue reinforcing your knowledge of Unit 4? Check out Unit 4 Trivia, either as a document or as a game.

• ⏭ Ready to move on to the next topic? Take a look at the collection of Unit 5 Resources.

• 📚 Want to review multiple units? Check out all of the AP Bio FRQs.

• 🤝 Got more questions? Want to help others studying the same topic? Jump into a room in Hours!