Answer:
1. Sexual Reproduction
2. Genetic variations
Explanation:
Human reproduces through sexual reproduction. Sexual reproduction is the process of production of new progeny by the formation of male and female gametes (sperms and egg respectively) and fusion of gametes. During gamete formation, crossing over adds new gene combinations to the gametes. The genetic variations make the progeny of sexual reproduction different from each other and from the parents.
Answer:
The number of white blood cells in the blood can increase during an immune response. These cells travel through the circulatory system and the lymphatic system to an injured or infected area of the body. White blood cells leave the blood vessels and travel into the damaged tissue, where the immune response takes place.
I think you forgot to give the options along with the question. I am answering the question based on my knowledge and research. <span>The lowest level of environmental complexity that includes both living and non living factors is the ecosystem. I hope that this is the answer that has come to your desired help.</span>