Answer:
the form of a sperm cell helps it to travel apon ejaculation and impregnation of a female.
Answer:
antibodies
Explanation:
The third line of defense is specific resistance. This system relies on antigens, which are specific substances found in foreign microbes. Most antigens are proteins that serve as the stimulus to produce an immune response. The term "antigen" comes from ANTI-body GENerating substances.
Answer:
After about age 40 to 50, the body starts to break down bone mass faster than it builds it.
Explanation:
This is part of the natural aging process. Both men and women experience bone loss with age.
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