Transport in Living Organisms Quiz

Transport in Multicellular Organisms

• Multicellular organisms must transport fluids and gases within their bodies, including nutrients, water, gases (O2, CO2), waste, and others.
• Plants use pressure gradients and pressure potentials to transport water, minerals, and sugars through specialized tubes, while animals use a pump to move circulatory fluid through tubes called vessels.
• Both plants and animals have evolved highly convoluted surfaces to increase the area available for gas exchange, essential for respiration.
• General means of transport include gravity, pressure gradients, and electrochemical gradients.
• Transport occurs at various levels, including cell-to-cell, tissues, organs, and throughout the body, driven by concentration gradients.
• All transport requires some form of energy, which can be passive (thermodynamically favorable) or active (requiring metabolic energy, often ATP hydrolysis).
• Diffusion, osmosis, and bulk flow are mechanisms of short and long-distance transport, regulated by membranes and affected by factors such as surface area to volume ratio.
• Osmosis is the diffusion of water across a selectively permeable membrane, moving from high to low concentration until equilibrium is reached.
• Active transport, driven by ATP, includes cation pumps such as H+, Na+-K+, and Ca2+ pumps, establishing electrochemical gradients.
• Secondary active transport, or cotransport, moves substances against their concentration gradient, for example, proton pump glucose symporter.
• Long-distance transport is pressure-dependent, occurring via plant and animal vascular systems, driven by mass movement of molecules from areas of high to low pressure.
• Plants need water for physical support, chemical reactions, photosynthesis, temperature control, and transport of solutes, occurring through pathways such as the vascular system.