Energy Pathway

Energy importance Most of your life is involved with energy whether you realize it or not. Energy is the cause of many wars. Energy is why you eat, sleep, go to school, and work. Energy powers your lights, cell phones, ipods, computers, TVs, cars, etc… but….

Energy importance … energy is also what powers your body and your brain.

Energy importance So, where does all this energy come from, how do we use it, and where does it go from here? That is what we will be learning about during this unit.

Types of energy Types of energy you might have heard of so far this year include: Kinetic Potential Heat Light Sound

Types of energy This unit we will be discussing these types of energy: Light energy Chemical energy (chemical potential or food energy) Mechanical energy Heat energy

The Sun – Energy’s beginning The energy you use to power your body originally came from the sun (the big yellow one.)

The Sun – Energy’s beginning The sun makes energy by doing nuclear reactions in its core. In the core of the sun, Hydrogen atoms are being smashed together under high temperature and pressure to form helium atoms. This nuclear reaction releases huge amounts of energy (more energy than a billion hydrogen bombs per second.)

The Sun – Energy’s beginning Electromagnetic energy leaves the sun in the form of heat and light. It takes about 8 minutes and 20 seconds for this heat and light energy to travel to earth. (It would take you 21 years to travel to the sun in a jet.)

From light energy to chemical energy We can not use light or heat energy to power our body, but… Some organisms are able to use the sun’s light energy to make food. Food energy is also called Chemical energy or chemical potential energy.

From light energy to chemical energy Organisms that can convert light energy into chemical energy are called producers. Almost all plants are producers (>99%). Photosynthesis is when producers make their own food using light energy from the sun. Pine drops

From light energy to chemical energy Photosynthesis occurs in the chloroplasts of plant or algae cells. Chloroplasts have a green pigment called chlorophyll in them that is able to transform light energy into chemical energy. (In the form of sugars or starches.)

From light energy to chemical energy Organisms that can make their own food (Producers) are also called autotrophs. “Auto” = self “troph” = nutrition (food) If they use the sun to make their own food (as most producers do,) they could be called photoautotrophs. (As opposed to chemoautotrophs.)

Review so far… So, producers, which are also called autotrophs, convert the light energy from the sun into chemical energy in the form of sugars. The reaction looks like this: 6CO2 + 6 H2O  C6H12O6 + 6O2

Eating sunlight! So, when you bite into a piece of lettuce, its like biting the light of the sun!

Importance of photosynthesis Most of the material that makes up the plant is made by the plant using the process of photosynthesis. All of the oxygen that we breathe each day comes from the process of photosynthesis. Almost all of the energy that powers your body came from the process of photosynthesis.

Respiration So, how does the chemical energy made in plants become energy that powers your body? Respiration is the process of changing chemical energy stored in food into usable chemical energy that can be used to power your body.

From stored chemical energy to usable chemical energy Respiration occurs in the mitochondria of cells. Sugar (from digestion) and oxygen, (from breathing) combine to form carbon dioxide gas, water, and ATP. ATP is usable chemical energy. Like a full battery for your body.

Respiration The formula for respiration looks like this: 6O2+ C6H12O6 6CO2 + 6 H2O + ATP (Usable chemical energy)

From usable chemical energy to mechanical energy ATP is used to power your muscles, your brain, your heart, and every other part of your body. When ATP is converted to ADP, the chemical energy stored in the ATP can be converted into mechanical energy, which is a combination of kinetic and potential energy.

From usable chemical energy to mechanical energy + heat When the chemical energy is converted into mechanical energy, there is a lot of heat energy that is also produced. Some of this heat energy is used to maintain body temperature, but most is lost to the environment. (About 60% of the energy is lost in the form of heat.)

Consumers Organisms that can’t do photosynthesis, and have to get their chemical energy by feeding on other organisms are called consumers.

Consumers Consumers are also called heterotrophs. “Hetero” = different “Troph” = food Heterotrophs (consumers) can get their energy by feeding on producers (herbivores), by feeding on other heterotrophs (carnivores), or both (omnivores).

So, the whole pathway looks like this… ATP

Quiz: What type of energy is this?

Quiz: What type of energy is this?

Quiz: What type of energy is this?

Quiz: What type of energy is this?