Identify the LETTER (A-I) of the part in DIAGRAM 1 and DIAGRAM 2 where EACH of the following occurs:

Here are the answers to your questions:

4.1.1:

• B: Vas deferens (or sperm duct)
• C: Testis
• G: Oviduct (or Fallopian tube)

4.1.2:

• a) Site where spermatogenesis occurs: $\boxed{\text{C}}$
• b) Serves the function of implantation: $\boxed{\text{F}}$
• c) Site where fertilisation occurs: $\boxed{\text{G}}$
• d) Secrets a sticky liquid that provides energy to the sperm cells: The glands responsible for this (seminal vesicles and prostate gland) are not labeled in Diagram 1. However, if a letter must be chosen from the male reproductive system, and considering the path of sperm, the secretions are added as sperm travel through the system. Among the labeled parts, none directly secrete this liquid. If forced to choose a letter from the male system, and acknowledging the diagram's limitations, no labeled part accurately fits the description of secreting this liquid. Given the strict instruction to select a letter, and that the liquid is added to sperm as they pass through the ducts, there is no perfectly correct answer among A, B, C, D. I will state that the relevant gland is not labeled.