Date | November 2016 | Marks available | 4 | Reference code | 16N.3.SL.tz0.10 |
Level | Standard Level | Paper | Paper 3 | Time zone | time zone 0 |
Command term | Explain | Question number | 10 | Adapted from | N/A |
Question
Discuss water distribution in trained athletes.
Explain the roles of the medulla and the loop of Henlé in maintaining the water balance of the blood.
Markscheme
percentage of water distribution depends on body composition ✔
muscle contains 65–75 % water whereas fat mass is 5–20 % water ✔
a trained athlete is likely to have more muscle mass compared to an untrained individual ✔
a trained athlete has greater muscle glycogen stores, which store more water ✔
exercise training increases percentage water distributed within the intracellular compartment ✔
a trained athlete will have greater water content in their body both intra and extracellularly ✔
sweat of a trained athlete is more dilute than an untrained individual which can affect water distribution during exercise ✔
a trained athlete has improved temperature regulatory process ✔
a trained athlete has increased blood plasma volume ✔
Accept answers in the converse.
the medulla is a region in the lower/mid-section of the kidney which has an increasing/high salt concentration ✔
«generally» the loop of Henle descends through into the medulla ✔
the high salt concentration/osmolarity in the medulla causes water to «passively» be drawn out of the descending loop of Henle ✔
the ascending loop of Henle actively pumps out salt ✔
the ascending is impermeable to water ✔
the descending is «only» permeable to water ✔
creates a concentration gradient between the medulla ✔
regulates a high concentration of urea near the medulla ✔
Examiners report
not always clear and an area for improvement.
not always clear and an area for improvement.