Question 1: The kidneys help regulate water balance in the body by controlling the concentration of urine. They respond to the body's hydration levels by adjusting the amount of water reabsorbed during urine formation. This process is essential for maintaining homeostasis.

Answer: The kidneys regulate water balance by controlling urine concentration through reabsorption, maintaining hydration and homeostasis.

Question 1: Define 'osmoregulation' and explain its importance in the human body.

Answer: Osmoregulation is the process of maintaining the balance of water and solutes in the body, crucial for proper cell function and overall homeostasis.

Question 2: Describe the role of the antidiuretic hormone (ADH) in water reabsorption in the kidneys.

Answer: ADH increases the permeability of kidney tubules to water, leading to greater water reabsorption and more concentrated urine.

Question 1: If a person consumes 2 liters of water and produces 1.2 liters of urine with a concentration of 600 mOsm/L, calculate the total osmolarity excreted in the urine (in milliosmoles). Use the formula: Total osmoles = volume of urine (L) × concentration (mOsm/L).

Answer: 720 milliosmoles

Question 1: Describe a basic experiment to test how water intake affects urine concentration. Include variables, controls, and safety precautions.

Answer: An experiment could involve measuring urine concentration after varying water intake levels while keeping diet and activity constant. Independent variable: water intake; dependent variable: urine concentration; control variables: diet, activity. Precautions include avoiding contamination and ensuring proper disposal of biological samples.

Question 1: A person drinks 1 liter of water and produces urine with a concentration of 800 mOsm/L. Another person drinks the same amount but produces urine with a concentration of 400 mOsm/L. Explain what these differences suggest about their kidney function and ADH levels.

Answer: The person with higher urine concentration likely has higher ADH levels and more effective water reabsorption, indicating normal kidney function. The other may have lower ADH activity or impaired kidney response, resulting in diluted urine.

Question 1: Explain how the kidneys respond when the body is dehydrated. Include the role of ADH and changes in urine concentration. (6 marks)

Answer: When dehydrated, blood osmolarity increases, stimulating the release of ADH from the pituitary gland. ADH makes the kidney tubules more permeable to water, increasing reabsorption. As a result, urine becomes more concentrated, conserving water and restoring balance.

Question 1: Describe how understanding kidney function and water balance can improve treatments for dehydration or kidney disease.

Answer: Understanding kidney regulation helps develop better rehydration therapies, dialysis techniques, and medications that target hormone levels like ADH to manage dehydration and kidney disorders.