AP Biology Questions on Feedback Loops in the Human Body

🧪 Quick Study Guide

• 🧬 Negative Feedback Loops: These loops maintain homeostasis by counteracting changes. A classic example is blood glucose regulation. When blood glucose rises, insulin is released to lower it; when it falls, glucagon is released to raise it.
• 🌡️ Positive Feedback Loops: These loops amplify changes, moving the system away from its initial state. Childbirth is a prime example: uterine contractions stimulate the release of oxytocin, which further intensifies contractions.
• 🩸 Blood Glucose Regulation: Involves the interplay of insulin (produced by beta cells) and glucagon (produced by alpha cells) in the pancreas.
• ⚙️ Thermoregulation: Controlled by the hypothalamus. When body temperature rises, the body sweats and blood vessels dilate. When body temperature falls, the body shivers and blood vessels constrict.
• 💧 Osmoregulation: Regulates water balance in the body. Antidiuretic hormone (ADH) plays a crucial role. When the body is dehydrated, ADH is released, increasing water reabsorption in the kidneys.
• hormone (ADH) plays a crucial role. When the body is dehydrated, ADH is released, increasing water reabsorption in the kidneys.
• 🔄 Key Concept: Homeostasis is maintained through feedback mechanisms.

Practice Quiz

1. Which of the following is an example of a negative feedback loop in the human body?
   1. A) Blood clotting
   2. B) Childbirth
   3. C) Regulation of blood glucose levels
   4. D) Fever increasing due to infection
2. What is the primary role of insulin in glucose regulation?
   1. A) To increase blood glucose levels
   2. B) To decrease blood glucose levels
   3. C) To inhibit glucagon secretion
   4. D) To stimulate glycogen breakdown
3. Which hormone is released when blood osmolarity is high, leading to increased water reabsorption in the kidneys?
   1. A) Aldosterone
   2. B) Atrial natriuretic peptide (ANP)
   3. C) Antidiuretic hormone (ADH)
   4. D) Cortisol
4. What is the function of glucagon?
   1. A) To lower blood glucose levels by promoting glucose uptake into cells
   2. B) To increase blood glucose levels by stimulating glycogen breakdown in the liver
   3. C) To inhibit insulin secretion
   4. D) To promote protein synthesis
5. During thermoregulation, what response occurs when body temperature decreases?
   1. A) Vasodilation and sweating
   2. B) Vasoconstriction and shivering
   3. C) Increased ADH secretion
   4. D) Decreased metabolic rate
6. Which of the following is an example of a positive feedback loop?
   1. A) Regulation of body temperature
   2. B) Regulation of blood pressure
   3. C) Uterine contractions during childbirth
   4. D) Regulation of blood pH
7. What part of the brain is the primary control center for thermoregulation?
   1. A) Cerebellum
   2. B) Hypothalamus
   3. C) Medulla oblongata
   4. D) Thalamus