Oxygen-Carrying Protein in the Blood: Hemoglobin. Hemoglobin is the protein that transports oxygen (O 2) in human blood from the lungs to the tissues of the body. Proteins are formed by the linking of amino acids into polypeptide chains.n hemoglobin, each subunit contains a heme group, which is displayed using the ball-and-stick representation in Figure 2. Each heme group contains an iron atom that is able to bind to one oxygen (O 2) molecule.
Decomposer: is an organism, usually a bacterium or fungus, that breaks down the cells of dead plants and animals into simpler substances. A fungus, such as this mushroom, is a decomposer of dead plants.
The group of organisms called decomposers forms the final link in the food chain. They break down dead animals and plants and return vital nutrients to the soil. Some decomposers, like fungi, can be seen without a microscope, but much of the decomposition process is carried out by microscopic bacteria.