Quick revision: every question with its correct answer. For the full explanation, open the relevant test and tap View Solution.
9.2 Membrane Transport β Test 1
Q1. Which of the following are endocytic receptors?β LDL receptor and cation-independent mannose-6-phosphate receptor
Q2. All statements about transfer of damaged plasma-membrane proteins to the lysosome are true EXCEPT:β The process is independent of ESCRT proteins
Q3. The proteins that form channels between two neighbouring cells, connecting their cytoplasms, are:β Connexins (gap junctions)
Q4. The superfamily of membrane transporters that actively transports a variety of small molecules (sugars, peptides, amino acids) using ATP is:β ABC transporter
Q5. Fatty acids are transported across the cell membrane mainly by:β Facilitated transport
Q6. The glucose transporter expressed predominantly in liver (and pancreatic Ξ²-cells) is:β GLUT2
Q7. The glucose transporter expressed mainly in liver cells is (variant):β GLUT2
Q8. GLUT3, a class I facilitative glucose transporter, is mainly present in:β Brain (neurons)
Q9. Lactose uptake in E. coli is mediated by:β Secondary active transport
Q10. The NaβΊ/KβΊ-ATPase maintains the membrane potential by pumping:β NaβΊ and KβΊ in opposite directions, each against its gradient
Q11. Which amino-acid residue is transiently phosphorylated during the NaβΊ/KβΊ-ATPase cycle?β Aspartic acid
Q12. Which residue is phosphorylated during sodiumβpotassium ATPase function? (variant)β Aspartic acid
Q13. Valinomycin is an ionophore responsible for the downhill transmembrane transport of:β KβΊ
Q14. Gramicidin A differs from valinomycin in that it:β Forms a transmembrane channel permeable to monovalent cations
Q15. In secondary active transport, the energy to move a solute against its gradient comes from:β An electrochemical ion gradient (e.g. NaβΊ or HβΊ) set up by a primary pump
Q16. The mitochondrial ADP/ATP translocase (adenine nucleotide translocator) exchanges:β ADP in for ATP out across the inner membrane
Q17. Aquaporins increase membrane permeability specifically to:β Water
Q18. During receptor-mediated endocytosis (e.g. of LDL), the coat protein that forms the invaginating vesicle is:β Clathrin
Q19. In facilitated diffusion, the transported solute moves:β Down its concentration gradient via a specific carrier/channel, without ATP
Q20. Macromolecules pass between the nucleus and cytoplasm through:β Nuclear pore complexes
Q21. An ionophore that collapses a membrane HβΊ gradient by carrying protons across the bilayer acts as a(n):β Uncoupler / protonophore