Neco Model Questions Vol1 2019 Biology Question 6

A laboratory study examined how plasma antidiuretic hormone (ADH) concentration influences urine concentration and volume in healthy adults over a 24‑hour period. The subjects were placed under three controlled conditions that produced low, moderate and high plasma ADH levels. The results are shown in the table below. | ADH level | Urine osmolality (mOsm kg⁻¹) | Urine volume (L day⁻¹) | |-----------|-----------------------------|------------------------| | Low | 150 | 2.5 | | Moderate | 300 | 1.5 | | High | 600 | 0.8 | Assume that the filtered load of plasma water by the kidneys is approximately constant at 2.5 L day⁻¹ for all three conditions. Answer the following questions.