Waec Model Questions Vol1 2018 Biology Question 21

Practice objective / multiple choice question 21 from the 2018 Waec Model Questions Vol1 Biology examination.

Waec Model Questions Vol1 2018 Biology Objective / Multiple Choice Hard Difficulty
Question 21 WAEC_MODEL_QUESTIONS_VOL1 • 2018 • BIOLOGY • objective

A semi‑aquatic amphibian species occurs in two habitats. In fast‑flowing streams its skin thickness is 0.8 mm and its measured cutaneous respiration rate is 12 ml O₂ h⁻¹ g⁻¹. In stagnant ponds the same species has a skin thickness of 1.2 mm and a respiration rate of 8 ml O₂ h⁻¹ g⁻¹. Assuming oxygen diffusion through the skin obeys Fick's law, where the diffusion rate is proportional to the ratio of skin surface area (A) to thickness (t) (rate ∝ A/t) and that the proportionality constant is the same in both habitats, determine the ratio of the effective skin surface areas (Aₚond / Aₛtream). What does this imply about the primary morphological adaptation that enables the amphibian to maintain higher oxygen uptake in streams?

Answer Options

A. The effective skin surface areas favor the stream (ratio = 0.67); the primary adaptation is a thicker skin in the stream environment.
B. The effective skin surface areas are twice as great in the pond (ratio = 2); the main adaptation is a reduced metabolic demand in the pond habitat.
Correct Answer C. The effective skin surface areas are equal (ratio = 1); the key adaptation is the reduced skin thickness in the stream habitat.
D. The effective skin surface areas are larger in the pond (ratio = 1.5); the key adaptation is an increased surface area in the pond habitat.
Correct Answer
C
Correct Option:
The effective skin surface areas are equal (ratio = 1); the key adaptation is the reduced skin thickness in the stream habitat.

About This Question

This is Waec Model Questions Vol1 2018 Biology Question 21. It is a objective / multiple choice question from the 2018 Waec Model Questions Vol1 Biology examination.

Difficulty level: Hard .

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