Answer:
Not enough information is given but my mom is in the medical feild and she says that a condition common with age is presbyopia. It causes the leanses in your eye to become less flexable and less able to thicken therefore less able to focus on near by objects. Another is catteracts which I assume you already know about so I will not explain.
Explanation:
1. physical activity
2. metabolism
3. hormones
4. temperature
5. palatability
6. psycology
7. social influences.
This is what I got hope it helps!
Sperm is a sex cell that is created by meiosis and is needed for sexual reproduction.
