Ijmb Model Questions Vol1 2025 Biology Question 6

Practice essay / theory question 6 from the 2025 Ijmb Model Questions Vol1 Biology examination. This question covers Excretion, Fish physiology, Nitrogen metabolism .

Ijmb Model Questions Vol1 2025 Biology Essay / Theory
Topics: Excretion Fish physiology Nitrogen metabolism
Question 6 IJMB_MODEL_QUESTIONS_VOL1 • 2025 • BIOLOGY • essay

A laboratory investigation is carried out to compare the excretory efficiency of two freshwater fish species, Species X and Species Y, kept in identical aquaria.

Question Parts

( a )
Outline the main organs involved in nitrogenous waste excretion in freshwater fish and the form of nitrogenous waste they primarily eliminate.
( b )
The experiment measures the concentration of ammonia in the water after 24 h. Species X shows an increase from 0.02 mg L⁻¹ to 0.12 mg L⁻¹, while Species Y shows an increase from 0.02 mg L⁻¹ to 0.08 mg L⁻¹. Calculate the total amount of ammonia excreted by each species over the 24 h period, assuming each aquarium holds 100 L of water and the fish are the only source of ammonia.
( c )
Discuss two physiological or behavioural adaptations that could explain the observed difference in ammonia excretion between the two species.
( d )
If the water temperature is raised from 25 °C to 30 °C, explain how this change is likely to affect the rate of ammonia excretion in both species, citing the underlying biochemical principle.

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About This Question

This is Ijmb Model Questions Vol1 2025 Biology Question 6. It is one of the essay questions from the 2025 Ijmb Model Questions Vol1 Biology examination.

The question covers Excretion, Fish physiology, Nitrogen metabolism .

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