Cambridge International A Level · Marine Science (9693)
5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Movement of substances.
Which of the following processes describes the movement of specific molecules across a cell membrane through a carrier protein, moving from an area of higher concentration to an area of lower concentration without the expenditure of metabolic energy?
Marine teleost fish maintain their blood at a higher (less negative) water potential than the surrounding seawater. Which statement correctly explains the net movement of water across the permeable membranes of their gills and the classification of the seawater?
Which statement best explains why ions like \(\text{Na}^+\) and \(\text{Cl}^-\) require facilitated diffusion to enter a cell, rather than simple diffusion through the phospholipid bilayer?
Which of the following best defines water potential in the context of marine biology?
A sample of marine animal tissue is placed in a solution with a water potential of \( -2500\text{ kPa} \). If the water potential inside the cells is \( -1200\text{ kPa} \), which statement correctly describes the net movement of water and its effect on the cells?
State the main difference between simple diffusion and active transport regarding the concentration gradient and energy requirement.
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A spherical marine larva has a radius of \( 0.5 \text{ mm} \). Using the formula for surface area \( 4\pi r^2 \) and volume \( \frac{4}{3}\pi r^3 \), calculate its surface area to volume ratio and state how this ratio affects its reliance on simple diffusion.
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Predict and explain the physiological changes that would occur in an animal cell moved from seawater to a solution with a much higher (less negative) water potential.
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(a) Describe how a student could use Visking tubing to investigate the effect of the concentration gradient on the rate of osmosis. \( [3] \)
(b) Identify one variable that must be controlled during this investigation to ensure valid results are obtained. \( [1] \)
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A student investigates the effect of surface area to volume ratio on the rate of diffusion using agar blocks of different sizes.
(a) Describe how the student could use agar blocks containing an indicator and a dilute acid to investigate this principle.
(b) Predict and explain how the time taken for the acid to reach the center of the block would change as the size of the block increases.
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