Human cells need oxygen for respiration. What system of the body is responsible for transporting an oxygen molecule to different locations throughout the body?

The cell wall is the part of a plant cell that acts as a barrier and provides support to the cell. It is a rigid, protective structure located outside the cell membrane and is composed primarily of cellulose, a complex carbohydrate. The cell wall gives plant cells their characteristic shape and provides mechanical support, preventing the cell from bursting due to osmotic pressure. It also helps regulate the movement of water and solutes into and out of the cell and protects the cell from pathogens and mechanical damage. In addition to cellulose, the cell wall may contain other polysaccharides, proteins, and lignin, depending on the type of plant cell and its function.

Strep throat is a bacterial infection caused by group A Streptococcus bacteria, specifically Streptococcus pyogenes. It is a common infection that affects the throat and tonsils, causing symptoms such as sore throat, fever, swollen lymph nodes, and difficulty swallowing. Strep throat is highly contagious and spreads through respiratory droplets when an infected person coughs or sneezes. It is typically treated with antibiotics to prevent complications and reduce the risk of spreading the infection to others. Other diseases caused by bacteria include tuberculosis, pneumonia, urinary tract infections, and bacterial meningitis.

Exocytosis is the process by which materials are released from a cell by fusing vesicles containing the materials with the plasma membrane, causing the vesicle contents to be expelled into the extracellular environment. It is a form of bulk transport that is used by cells to export molecules such as proteins, neurotransmitters, hormones, and waste products. Exocytosis plays essential roles in various cellular functions, including secretion, cell communication, and the removal of cellular waste.

Contractile vacuoles are organelles found in some protists and single-celled organisms, primarily freshwater unicellular organisms. These vacuoles are responsible for regulating the water content of the cell by actively pumping excess water out of the cell. Contractile vacuoles collect excess water from the cytoplasm through a process of osmosis, where water diffuses into the cell due to differences in solute concentration between the cell and its environment. Once filled, contractile vacuoles contract rhythmically, expelling the excess water from the cell to maintain osmotic balance and prevent cell swelling or bursting. This process is particularly important for organisms living in hypotonic environments where water uptake is significant.