Energy! Big Idea #2: Energy is needed to do stuff.

Big Idea #2 Biological Systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis

Essential Knowledge 2A1: All living systems require constant input of free energy.

Energy Ability to do something (i.e. move) 2 general types: – Potential energy- stored energy – Kinetic energy – moving energy

Potential vs. Kinetic Energy Resting objects Nuclear Hydroelectic (water behind a dam) Food Moving objects Radiation (light particles/waves) Thermal (heat) Electrical (movement of electrons)

1 st Law of Thermodynamics Energy cannot be created nor destroyed May change from one form to another Ex: Solar Energy  Chemical Energy

2 nd Law of Thermodynamics No rxn is 100% efficient  lose energy Systems spontaneously increase entropy (disorder)

Entropy Amount of energy in an unusable form – usually heat Is always increasing b/c systems are always losing usable forms of energy

Biologically Speaking… Living orgs require an energy input. Ex: orgs must get energy from sun, deep thermal vents, or eating Remember 10% Rule !

Order and Organization Require Energy Things naturally break down – to keep them from breaking down or to put them together requires an input of energy

Energy Coupling Processes that release energy are coupled to ones that require an input of energy More energy must be released than is required

Example Flexing a muscle requires an energy input and breaking down food releases energy (ATP). Do You Have Any Band Aids?

Exergonic Reactions Release free energy Used in living things to provide energy for other processes

The Most Significant Exergonic Reaction ATP + H 2 O  ADP + Pi + Energy

Making ATP is an Endergonic Reaction Requires an input of energy Made in cellular respiration (input of chemical energy in food)

Uses of Free Energy Maintain body temp (some organisms)/Internal temp regulation Reproduction Growth Movement

Body Temp Regulation Endothermy: Use heat released by metabolic reactions to keep a stable temp Ex: Humans 98.6⁰

Body Temp Regulation Ectothermy: Use external sources to try to maintain body temp. Ex: snakes/reptiles

Reproduction Requires a huge amount of energy Many species only reproduce when energy is available – I.e. most plants flower in spring when sunlight energy is abundant

Growth Extra free energy not needed for cellular processes (movement and reproduction) can be put to growth Ex: extra calories become stored fat

Energy Deprivation Mass is broken down to provide energy No energy input = death RIP Tako 

Smaller Organisms Require More Food Per Body Mass Smaller orgs have more surface area to volume  lose more heat… must replenish that energy loss by eating more

The Trophic Levels Energy goes up food chain At every level energy is being lost due to entropy.

So…less energy available for high levels of food chain Rarely enough energy to support more than 3-4 levels on a food chain

Energy on an Ecological Level The more energy available for a population, the more it will grow Ex: rain forests have most abundant plant life – constant energy source

Energy Doesn’t Cycle!!!!!!