UW Madison zoology-biology 101 EXAM 3 latest solution update 2023

Basics of diffusion, gradients, and how they relate - Diffusion: spontaneous movement of very small things. It requires no energy investment by the organism (other than keeping the temperature above freezing) --direction is random Gradients: top of gradient = high concentration, bottom of gradient = low concentration --diffuses high to low Basics of diffusion across a semipermeable barrier - Factors that speed up or slow down diffusion - size: smaller things diffuse faster the viscosity of medium: diffusion is slower in more viscous media temperature: diffusion is faster at higher temperatures only fast over short distances Why doesn't diffusion work well over long distances? - much more time required for diffusion to work (time increases as square of distance) Meaning of the phrase "Physiology enables multicellularity by...." - Physiology is the study of systems and mechanisms that allow multicellularity to exist/systems that enable multicellularity ? Difference between the challenges faced by most animals vs. challenges faced by a single celled organism (amoeba) - need 1: a cell must eat need 2: a cell must excrete need 3: a cell must respire problem 1: diffusion is slowed by surrounding cells problem 2: food & O2 might be consumed by other cells before they can reach cells far from the O2/food source problem 3: diffusion does not work well over long distances challenges to multicellularity: food, O2, CO2, and waste may have to pass many cells & travel long distances How, at a basic level, the digestive system, respiratory, and circulatory systems contribute to multicellularity - solution to challenges for food and waster: use digestive and circulatory systems to overcome challenges for food delivery and waste removal in the face of distance & cell density --these systems employ ADVECTION (powered bulk movement) of food and metabolic waste to complement diffusion **digestive system prepares food **circulatory system gets food to cells and takes waste away from cells solution to challenges for respiration: use respiratory and circulatory systems to overcome challenges for O2 delivery and CO2 removal in the face of distance and cell density **respiratory system obtains O2 and removes CO2 **circulatory system get O2 to cells and takes away CO2 --using advection as a complement to diffusion muscle system: POWERS advective movement within circulatory, digestive, & respiratory systems nervous system: REGULATES muscle, circulatory, digestive, & respiratory systems immune system: PROTECTS muscle, nervous, circulatory, digestive, & respiratory systems What does "economy of space mean"? - physiological systems tend to pack as much as possible into the smallest amount of volume --requires that the rules of geometry are adhered to Basic shapes and forms used in physiology and how those shapes are exploited by physiology - spheres have a high ratio of volume to surface area & thus are good for sorting things hollow cylinders (tubes) --results in proportionally more surface area to volume