INTERRELATIONSHIPS OF ORGANISMS

LIVING THINGS

ENERGY= Capacity to do work or cause change Free energy = energy actually able to do work Chemical energy = stored (potential) energy

WHY DO WE NEED ENERGY? For metabolism ( chemical) For movement of nutrients Mechanical movement

HOW DO WE GET ENERGY? Autotrophs = obtain energy and nutrients from nonliving sources (abiotic) Heterotrophs = obtain it from other organisms, living or dead

HOW? PHOTOSYNTHESIS = CHEMICAL REACTIONS THROUGH WHICH AUTOTROPHS CAPTURE ENERGY FROM SUNLIGHT AND USE IT TO FORM ORGANIC COMPOUNDS FROM CO2 AND H2O SOME ENERGY IS STORED AND USED LATER; SOME USED FOR GROWTH, REPAIR AND MAINTENANCE

Cellular respiration = series of chemical reactions that convert stored energy to free energy to do cellular work Both autotrophs and heterotrophs use this process

WHAT IS A FOOD WEB? Producers = make food Consumers = eat plants and other organisms Decomposers = use dead organisms for food Abiotic and biotic factors

ECOSYSTEM Interaction of biotic and abiotic components in a given area (pond, forest) Within each ecosystem, a variety of habitats

HOW DOES ENERGY FLOW? Governed by the laws of thermodynamics (bioenergetics) 1. Energy cannot be created or destroyed but it can be transferred or transformed

WHAT DOES THIS MEAN FOR LIVING ORGANISMS? Must get energy from outside source Autotrophs -> sun; heterotrophs -> chemical energy stored in food; chemical energy is transformed into free energy, heat is also released

2. Natural processes tend to proceed in a way that increases disorder (entropy) of a system Energy released as heat is no longer available to do work

As free energy decreases, system becomes increasingly disordered As free energy decreases, entropy increases As energy flows through a food web, it is eventually released into surroundings as heat

THIS ONE WAY ENERGY FLOW MEANS THAT IN ORDER TO AVOID ENTROPY, LIVING ORGANISMS MUST CONSTANTLY OBTAIN ENERGY (FOOD) FROM THEIR SURROUNDINGS