Integration of Body Systems · Paper 1 — Free Biology HL Practice Questions

In type 1 diabetes, the beta cells of the pancreas are destroyed by the immune system, so insulin is not produced. A patient has a fasting blood glucose concentration of 14.5 mmol/L, compared to the normal range of 4.0–6.0 mmol/L. Which statement best explains why blood glucose homeostasis cannot be maintained?

During childbirth, uterine contractions push the baby against the cervix, stimulating the brain to release more oxytocin, which intensifies contractions further. This cycle continues until delivery. Which type of feedback mechanism does this represent, and why?

A glomerular filtration rate (GFR) of $180 \text{ L day}^{-1}$ is measured in a healthy adult. The concentration of urea in blood plasma entering the glomerulus is $0.03 \text{ g per } 100 \text{ mL}$, and the concentration of urea in urine is $2.0 \text{ g per } 100 \text{ mL}$. The volume of urine produced is $1.5 \text{ L day}^{-1}$. What is the approximate mass of urea filtered at the glomerulus per day?