Respiratory- You breath faster to help supply the muscles with more oxygen.
Integumentary (skin) - Sweat helps cool down the body.
Answer:
Gene, a part of DNA that determines the trait of individual characteristics
Explanation:
Genetics, Medical problems, eating habits etc
Answer:
Variation explains the difference in traits between all living organisms.
Explanation:
Without variation it would be pretty impossible to notice any "differences" in traits, especially between living organisms.
