Zadanie 8, Paper 2, maj 2025, TZ1, Biologia IB HL
Wzorowane na: Biology HL Paper 2, May 2025, TZ1, pytanie 8. Treść, dane i kontekst są zmienione; sprawdzane umiejętności, format i punktacja jak w oryginale.
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Zadanie
Polecenie
Water influences the operation of organisms and the stability of their environments.
(a) Outline how cohesion between water molecules benefits organisms.
(b) Describe ecological consequences of ice loss and altered ocean circulation.
(c) Explain how hormones regulate kidney water reabsorption through negative feedback.
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Odpowiedź z klucza
(a)
Water is polar, with partially positive and negative regions. ✔
Neighbouring molecules attract one another through hydrogen bonding. ✔
Cohesion supports water transport in xylem by maintaining the continuous column under tension. ✔
Surface tension produced by cohesion can support small surface-dwelling organisms. ✔
The hydrogen-bond network makes evaporation energy-demanding, allowing evaporative cooling to remove body heat. ✔
The same intermolecular network contributes to high heat capacity, buffering aquatic temperatures, or to water remaining liquid across a broad biologically useful temperature interval. ✔
(b)
Ice loss removes habitat occupied by ice-dependent organisms. ✔
It can remove access to feeding or breeding sites. ✔
A valid affected species is identified, such as the ringed seal or polar bear. ✔
Altered currents may reduce nutrient upwelling. ✔
Reduced nutrient supply can lower phytoplankton growth and primary production. ✔
Food-web energy transfer or migration patterns can consequently change. ✔
(c)
Negative feedback opposes deviations and moves a variable back towards its regulated range. ✔
Osmoreceptors in the hypothalamus detect excessively concentrated body fluids. ✔
Dehydration or raised osmotic concentration stimulates increased ADH secretion. ✔
ADH enters the circulation from the pituitary; specifying the posterior pituitary is correct but not required. ✔
ADH increases functional aquaporin channels in collecting-duct membranes. ✔
Collecting ducts become more permeable to water and reabsorb more water from the filtrate. ✔
Water returns to the blood, or its solute concentration falls. ✔
A smaller volume of urine is produced, or the urine is more concentrated. ✔
Blood water potential rises or its relative water content increases. ✔
As fluid concentration returns to its regulated range, ADH release decreases. ✔
Quality of communication: the complete response is understandable on first reading, focused and sufficiently concise, without substantial repetition or irrelevant material. ✔
Schemat punktowania
Part (a): award any 4 listed valid points, maximum 4 marks. Part (b): award any 4 listed valid points, maximum 4 marks. Part (c): award any 7 listed valid points, maximum 7 marks. Award 1 additional mark for clarity of communication across the whole response. Maximum 16 marks.