Why are cell walls present in plant cells but absent in animal cells?

Plzz hurry im being timed during times of vigorous physical activity, muscles require a constant supply of oxygen. how does the body respond to these needs? a. breathing rate and heart rate both decrease. b. breathing rate and heart rate both increase. c. heart rate decreases, but breathing rate remains stable. d. breathing rate increases, but heart rate remains stable.

Which situation is an example of not doing work? lifting a couch throwing a baseball running up stairs carrying a box

What is the process by which biological parents pass traits such as hair type or eye color to their children