How does the circulatory system work?

Which two criteria must be met before scientist can use radiocarbon dating? explain your answer

Which of the following best describes the expensive tissue hypothesis? brains require more energy, so the gut had to be reduced, and larger brains and tool use led to higher quality diets. increasing body size means that homo neanderthalensis had to include more fat in its diet. brains require more energy, so the gut had to be reduced as brains got bigger. brains require more fat, so the gastrointestinal viscera (gut) had to expand, and hands were needed to acquire more food.

Facilitated diffusion move large molecules and/or polar molecules across the cell membrane. what does facilitated diffusion use to do this?