Umiejętności z tego działu sprawdzają 34 zadania wzorowane na arkuszach IB z lat 2022–2026. Dział pojawia się w 30 z 57 arkuszy w bazie.
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.…
A membrane contains aquaporin proteins. What role do they perform? A. They hydrolyse ATP to pump water against its potential gradient B. They attach water covalently to phospholipid tails C. They act only on the external membrane surface D. They provide…
(i) Distinguish the volume changes in the mRNA-treated cells from those in the controls. (ii) Explain how the introduced aquaporins produce this difference.
Molecules move across the plasma membrane by several routes. Describe three distinct membrane-transport processes.
An absorbed monosaccharide crosses an epithelial membrane through a transport protein without ATP use. Outline how facilitated diffusion moves the solute.
Which labelled component can act as a cell-recognition marker at the surface? A. P B. Q C. R D. S
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…
Identify the labelled components of this membrane model. A. P: glycoprotein; Q: integral protein B. P: phospholipid; Q: free ribosome C. P: peripheral protein; Q: cholesterol D. P: nucleic acid; Q: carbohydrate chain
Which substance–route pairing correctly describes movement through a cell membrane? A. Testosterone — directly through the lipid bilayer B. Starch — through an aquaporin C. A sodium ion — freely through the hydrophobic core D. A large antibody — through a…
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