Improve the student’s model of gas exchange by drawing the missing component.

The diagram can be improved by:

                                  Lungs

                                       ↓

                                   oxygen

                                       ↓

                      Red blood cells (carrying oxygen)

                                       ↓

                  Organs (like stomach and liver etc) from where carbon    

                               is taken and oxygen is supplied

                                         ↓

                   RBC's carrying Carbon dioxide to the lungs

The component which is missing in the diagram are the organs where exchange of gases occurs. The red blood cells carry oxygenated blood from the lungs to all parts of the body and carries the wast carbon dioxide gas from them back to the lungs. The carbon dioxide is then exhaled by the lungs.

1. loamy sand is about 80% sand with 10% clay and defined mostly by sand particles with some clay to provide structure and fertility. the sand particles are easily visible and the soil holds structure but breaks apart easily.

2. scott sand can improve his soil quality by incorporating more silt and organic matter into the soil. peat moss and organic matter can also be incorporated.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.