Introduction to Energy and Laws of Thermodynamics Why do living things need energy?

Life and Energy Life on earth differs from inorganic (non-living) material It is maintained in a different state to its surroundings. (homeostasis and metabolism) Cell contains the active chemicals of life (mainly in the cytoplasm) inside a semi-permeable membrane And therefore living cells can avoid their structure and chemistry falling back into a non-reactive (inorganic) state.

Energy exists in many forms such as light, heat, chemical and electrical.Energy exists in many forms such as light, heat, chemical and electrical. Energy is the ability to bring about change or to do workEnergy is the ability to bring about change or to do work Thermodynamics is the study of energyThermodynamics is the study of energy THERMODYNAMICS

PHYSICAL LAWS OF SCIENCE GOVERNING ENERGY RELATIONSHIPS Energy cannot be recycledEnergy cannot be recycled therefore there must be a constant supply therefore there must be a constant supply Involves Two Processes Matter can be recycledMatter can be recycled and Nature does it with perfection. and Nature does it with perfection.

TRANSFORMATION TRANSFORMATION – In short, the law of conservation of energy states that energy can not be created or destroyed, it can only be changed from one form to another or transferred from one body to another – the total amount of energy remains constant (the same). First law of thermodynamics: Energy can be transferred or transformed but Neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement in (b). (a) Chemical energy LAWS OF THERMODYNAMICS #1 - Conservation of Energy

Transformation always results in energy lost Transformation always results in energy lost – as unusable energy in the sense that work cannot be performed. This is usually in the form of heat. – Therefore transformation increases entropy (disorder) Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. (b) Heat co 2 H2OH2O + LAWS OF THERMODYNAMICS #2 - Law of Entropy

FREE ENERGY (available for work) vs. HEAT (not available for work) LAWS OF THERMODYNAMICS KineticEnergy Potential Energy Entropy Entropy

Two Important Questions Where does the energy needed for living organisms originate? Where does the energy needed for living organisms originate? How is energy used by these organisms? How is energy used by these organisms?

Living Organisms Metabolism – the flow of ENERGY through life Metabolism – the flow of ENERGY through life There are TWO SOURCES available There are TWO SOURCES available

The Source of High Quality Energy Most of the Energy arrives as electromagnetic radiation from the sun Most of the Energy arrives as electromagnetic radiation from the sun Supports photosynthesis (less than 2%) Supports photosynthesis (less than 2%) Powers the cycling of matter Powers the cycling of matter Drives climate and weather that distribute heat and H 2 O Drives climate and weather that distribute heat and H 2 O Solar radiation Energy in = Energy out Reflected by atmosphere (34%) UV radiation Absorbed by ozone Absorbed by the earth Visible light Lower Stratosphere (ozone layer) Troposphere Heat Greenhouse effect Radiated by atmosphere as heat (66%) Earth Heat radiated by the earth

SOURCE OF ENERGY FOR LIFE organic molecules  ATP & organic molecules sun solar energy  ATP & organic molecules.

The second is energy from within the earth itself. There are only a few ecosystems known to use this energy The second is energy from within the earth itself. There are only a few ecosystems known to use this energy SOURCE OF ENERGY FOR LIFE Nitrifing bacteria Nitrifing bacteria Halophiles (found in highly concentrated salt lakes) Halophiles (found in highly concentrated salt lakes) Thermophiles (found in hot springs and geysers) Thermophiles (found in hot springs and geysers) complex organic compounds reduced inorganic compounds chemoautotrophs oxygen

Photoautotrophs Autotrophs (self-nourishing) are called primary producers. Autotrophs (self-nourishing) are called primary producers. Photoautotrophs fix energy from the sun and store it in complex organic compounds Photoautotrophs fix energy from the sun and store it in complex organic compounds green plants green plants algae algae some bacteria some bacteria some protists some protists photoautotrophs simple inorganic compounds complex organic compounds light

Heterotrophs Heterotrophs (other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds. They require energy previously stored in complex molecules. Heterotrophs (other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds. They require energy previously stored in complex molecules. Examples of heterotrophs Examples of heterotrophs – Herbivores – eat plants – Carnivores – eat meat – Omnivores – eat both plants and meat – Scavengers – eat carrion – Saprophytes – eat dead or decaying material heterotrophs simple inorganic compounds complex organic compounds this may include several steps, with several different types of organisms heat

Food Chain

PHOTOSYNTHESIS 6CO 2 + 6H 2 O + ENERGY C 6 H 12 O 6 + 6O 2 Carbon Dioxide Water Glucose Oxygen CELLULAR RESPIRATION C 6 H 12 O 6 + 6O 2 Carbon Dioxide Water ATP 6CO 2 + 6H 2 O + LIGHT Glucose Oxygen