Relate channel structure and opening to the passive movement of particular ions across membranes.
Tę umiejętność sprawdza 9 zadań wzorowanych na arkuszach IB z lat 2022–2026.
A membrane’s molecular organization underlies selective transport and electrical properties. (a) Outline phospholipid structure and its interactions with water. (b) Explain how proteins enable substances to cross membranes. (c) Describe the establishment of a…
A sodium ion cannot readily cross the hydrophobic core of a lipid bilayer. Which pair of mechanisms can move it across a cell membrane? A. Osmosis and simple diffusion through lipid tails B. Channel-mediated diffusion and active transport through a pump C.…
An absorbed monosaccharide crosses an epithelial membrane through a transport protein without ATP use. Outline how facilitated diffusion moves the solute.
Which labelled regions in this membrane model are hydrophilic? A. I and II B. III and IV C. I and III D. II and IV
A cell in a freshwater organism is bounded by a phospholipid membrane. (a) Outline how phospholipid properties determine the membrane’s structure. (b) Describe the movement of substances through the membrane by facilitated diffusion. (c) Explain how electrical…
Water and dissolved substances connect the functioning of cells with the physical conditions of oceans. (a) Outline properties of water, linking each to its importance for living organisms. (b) Describe how water-soluble molecules and ions pass across cell…
A protein spans a phospholipid bilayer and provides a pathway for ions. Which arrangement of its regions is compatible with that location? A. A non-polar membrane-contacting surface and polar regions exposed to water B. Only polar regions in direct contact…
A neutral solute crosses a membrane through a selective channel. There is initially more of it outside than inside; no other process moves or consumes it. Which description fits this facilitated diffusion? A. ATP must be hydrolysed for every molecule…
Which combination describes the requirements and energy use of facilitated diffusion? A. A suitable protein and a gradient, with no direct ATP use B. A protein and ATP hydrolysis, always against the gradient C. ATP hydrolysis without any membrane protein D. A…
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