N22 P1 explanations

1. N22Q1 C P – vesicle / secretory vesicle Q- rER R – mitochondrion (double memb) S – Nucleus (double memb) 2. N22Q2 A X is nucleolus, codes for ribosome 1- True : needs ribosome for translation 2- True : X codes for ribosome 3- False : does not affect transcription 4- False : does not affect replication 3. N22Q3 A 1 – different from Bacteria ; bacteria 2 fatty acid chain 2 – different from bacteria : cell wall made of peptidoglycan 3 – same as bacteria : contains circular DNA 4 – different from bacteria : ester linkage in bacteria 5 – same as bacteria : 70S ribosomes 4. N22Q4 B Not HIV, as no RNA-dep RNA pol. Not T4, as no envelope Not lamda phage, as no envelope 5. N22Q5 C Glycerol does not have double bonds, all 2 molecules have OH groups. 6. N22Q6 D Grey portion of the protein is hydrophobic. Hence will form hydrophobic interaction with the hydrophobic tail of the detergent. 7. N22Q7 A Pyruvate is the substrate and the substrate concentration decreases with time as more substrate is being converted to product. However, the rate plateaus after a while as other factors may become limiting, e.g. NADH concentration 8. N22Q8 D A – False; CD34 stem cells are multipotent; only ESCs are pluripotent and found in the ICM of the blastocyst; B – False; iPSCs are derived from differentiated somatic cells not from other stem cells; C – False; Since the Wnt pathway signals bind to GPCRs as stated in the question stem, they are likely to be ligands involved in cell signalling; D – True; CD34 multipotent stem cells which differentiate into a range of limited cell types can switch to form Lgr5 stem cells which can differentiate into other limited cell types via a different pathway. This demonstrates plasticity of stem cells. 9. N22Q9 C Statement 2 is wrong because not the entire base sequence of tRNA is complementary to that of mRNA - only the anticodon region on tRNA is complementary to the codon region on mRNA; Statement 3 is wrong because the bond formation between tRNA and mRNA is hydrogen bonds formed by complementary base pairing between the anticodon and the codon – it does not depend on the aminoacyl tRNA synthetase enzyme; 10. N22Q10 C Statement 1 – can occur in both Statement 2 – can occur in prokaryotes but not in eukaryotes Statement 3 – can occur in eukaryotes but not in prokaryotes 11. N22Q11 A 1 – viruses also have genes coding for capsid proteins, etc 2 – viruses have genes coding for virus specific enzymes, e.g. lysozyme, etc GCE A Level H2 Biology 9744 Biology November 2022

3 – all genes should have a promoter 4 – since viral DNA genomes can replicate, it should have an origin of replication 12. N22Q12 D Option D has the most errors (4) Note: OmpC porin – outer membrane porin C allows passive diffusion of small molecules across the outer membrane 13. N22Q13 D Statement 1: Incorrect because transfer of plasmid DNA is from F+ cell to F- cell and not