B. Endoplasmic reticulum

Here are the answers to the objective questions:

1. B. Endoplasmic reticulum
2. D. Taxonomy
3. C. Commensalism
4. C. Sunlight
5. B. Topography
6. B. Semicircular canals
7. C. Ball and socket joint
8. C. Tendon
9. C. Transpiration
10. D. Right ventricle
11. B. Incomplete dominance
12. C. Blood group
13. D. Bacterium
14. C. Carbon(IV) oxide
15. C. Nephron
16. A. Liver and Kidney
17. B. Photosynthesis
18. B. Female Anopheles mosquito
19. C. Thymine
20. D. Amino acids
21. C. Producers -> Herbivores -> Carnivores
22. D. Liver
23. C. Crop rotation
24. C. 9:3:3:1
25. C. Lymphocytes
26. C. Haemophilic male
27. B. Grana
28. B. One ovum fertilized by one sperm splits into two.
29. C. 46
30. C. Anemometer
31. C. Adrenaline
32. C. Nitrogen fixation
33. C. Modified forelimbs into wings
34. B. Plasmolysis
35. C. Pulmonary vein
36. B. Epigeal
37. B. The functional role of an organism in its environment.
38. C. Blood grouping
39. A. Stem cuttings
40. C. Charles Darwin