A Level Biology Definitions

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Across
  1. 3. Enzyme that joins a human gene into a plasmid in genetic engineering.
  2. 5. Protein involved in protein synthesis.
  3. 7. Process where a complementary mRNA strand is made from DNA.
  4. 9. Cycle in photosynthesis generating TP from CO₂.
  5. 12. Ability of an organism to maintain a stable internal environment.
  6. 13. Movement of molecules against their concentration gradient.
  7. 14. Environmental factors that influence allele frequencies in populations.
  8. 19. Biological catalysts.
  9. 21. Protein molecules on cell surfaces that detect specific substances.
  10. 22. Protein fibres responsible for muscle contraction.
  11. 26. Small, circular DNA molecules in bacteria.
  12. 27. pH scale measures concentration of these ions.
  13. 29. Process by which water moves down a potential gradient across a membrane.
  14. 30. Diagram showing evolutionary relationships between species.
  15. 31. Type of immunity gained through vaccination.
  16. 33. Bacterial gene‑expression system controlled by an operator region.
  17. 34. Site of aerobic respiration.
Down
  1. 1. Form of natural selection favouring average phenotypes.
  2. 2. Engulfing and digesting pathogens by cells such as macrophages.
  3. 4. The body’s ability to resist infection.
  4. 6. Structure containing grana where the light‑dependent reaction occurs.
  5. 8. Cell division producing four genetically varied haploid cells.
  6. 10. Genetic change in a population over time.
  7. 11. To make an exact copy of DNA.
  8. 15. H+ movement that drives ATP synthase.
  9. 16. A community plus all the abiotic conditions.
  10. 17. Molecule formed when oxygen acts as the final electron acceptor.
  11. 18. First stage of respiration in which glucose is split into pyruvate.
  12. 20. The alleles an organism possesses.
  13. 23. The observable characteristics of an organism.
  14. 24. Structure carrying amino acids to ribosomes.
  15. 25. Variety of living organisms in an area.
  16. 28. Enzyme that unwinds DNA.
  17. 32. Molecule containing anticodons.