BIOB50 Ch.5

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Biological Sciences
Course Code
Marc Cadotte

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Chapter 5 Coping with Environmental Variation Energy Introduction y Energy is the most basic requirement for all organisms and without energy inputs biological functioning ceases Enzyme systems fail wo replacement proteins cell membranes degrade and organelles cease to operate wo energy to maintain and repair themSources of Energyy Organisms obtain energy from sunlight from inorganic chemical compounds or through the consumption of organic compounds y Energy exists in many forms in the environment Light from the sun a form of radiant energy Objects that are cold or warm to out touch have different amounts of kinetic energy associated w motion of the molecules that make up the objects Chemical energy is stored in bonds of food molecules Radiant and chemical energy are the forms organisms use to meet the demands of growth and maintenancewhile kinetic energy is impt for determining the rate of activity and metabolic energy demand of organisms y Autotrophs are organisms that assimilate energy from sunlight photosynthetic organisms or from inorganic chemical compounds in their environment chemosynthetic archaea and bacteriaThey convert the energy of sunlight or inorganic compounds into chemical energy stored in the carboncarbon bonds of organic compounds typically carbohydratesy Heterotrophs are organisms that obtain their energy by consuming energyrich organic compounds from other organisms energy that ultimately originated w organic compounds synthesized by autotrophs Include organisms that organisms that consume nonliving organic matter like earthworms and fungi and organisms that consume live hosts but dont necessarily kill them as well as consumers predators that capture and kill their food source preyAutotrophyy Radiant and chemical energy captured by autotrophs is converted into stored energy in carboncarbon bondsy The vast majority of the autotrophic production of chemical energy on Earth occurs through photosynthesis a process that uses sunlight to provide the energy needed to take up CO and synthesize carbon compounds2y Although its contribution to the overall energy picture is lower chemosynthesis a process that uses energy from inorganic compounds to produce carbohydrates is impt to some key bacteria involved in nutrient cyclingHeterotrophyy Heterotrophs have evolved mechanisms to acquire and assimilate energy efficiently from a variety of organic sourcesy They consume energyrich organic compounds food from their environment and convert them into usable chemical energy primarily ATP by glycolysisy Their energy gain from food depends on the chemistry of the food which determines its digestibility and amount of energy per unit mass it containsy The effort invested in finding and obtaining the food also influences how much benefit the heterotrophy gets from consuming it Eg microorganisms that consume detritus in the soil invest little energy in obtaining food but the detritus has low energy content
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