Natural variation provided the phenotypes that natural selection then acted on, over time causing evolution
Answer:
Respiration...................
They are positively and negatively charged
Answer:
Organs are made of different kinds of tissues that work together.
Explanation:
All the organs are made of tissues, the organ level is the next level up from tissues. The groups of tissues work together. The tissues are specialized cell group, the animal body is made of 4 types of tissues: epithelial, connective, muscle, nervous.
Organs and tissues are levels of organization. Organs are structures made up of two or more tissues, together they carry out a particular function.
