Explain how energy from ATP enables specific particles to move against their concentration gradient.
Tę umiejętność sprawdza 8 zadań wzorowanych na arkuszach IB z lat 2023–2026.
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.…
Molecules move across the plasma membrane by several routes. Describe three distinct membrane-transport processes.
A cell maintains the ion concentrations shown. Which mechanism can sustain these opposing gradients? Ion | Cytosol / mmol L⁻¹ | External fluid / mmol L⁻¹ Potassium | 142 | 4.5 Sodium | 12 | 138 A. Passive movement of both ions through permanently open channels…
A membrane protein hydrolyses ATP while transporting calcium from low concentration to high concentration. What type of protein is it? A. An adhesion glycoprotein B. A water channel C. An active-transport pump D. A passive calcium pore
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…
An intestinal absorptive epithelial cell contains many mitochondria. Outline why this supports the cell’s function.
Deduce how each compound would affect stomach pH.
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