Which of the following statements is true? Population density is number of individual organisms of a species living in a unit of area.
Water is not a limiting factor in an aquatic ecosystem.
An ecosystem can carry an unlimited number of organisms.
In a balanced ecosystem, there is no competition for resources.

Hemoglobin is the compound in red blood cells that carries oxygen to the body. the distribution of hemoglobin in women in g/dl of blood is approximately normally distributed with mean 14 and standard deviation 1. too little hemoglobin, and you're anemic. 2. too much, and (unless you live at high altitudes), you can have other problems.

One gene can influence trait(s). one trait can be determined by gene(s).

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain