Ch. 7.1: Sunlight Powers LifeCh. 7.1: Sunlight Powers Life

VocabularyVocabularyautotrophautotroph heterotrophheterotroph cellular respirationcellular respiration plasma membraneplasma membranephotosynthesisphotosynthesis producerproducer consumerconsumer

Objectives: Objectives: 1.1. Compare and contrast how autotrophs & heterotrophs obtain food.Compare and contrast how autotrophs & heterotrophs obtain food.2.2. Explain how cellular respiration harvests the energy in food.Explain how cellular respiration harvests the energy in food.

Ch. 7.1: Obtaining Food

Producer/Autotrophs:Organisms make their own food from inorganic molecules.Photosynthetic organisms (Plants, plankton, algae, & photosynthetic bacteria)Support entire food web.

Ch. 7.1: Obtaining Food

Consumer/HeterotrophsObtain food by eating other organisms. (Not photosynthetic).

Ch. 7.2: Food Stores Chemical Energy

Vocabulary:Kinetic energy Potential energyThermal energy Chemical energyCalorie

Objectives:1. Distinguish between kinetic and potential energy.2. Explain what chemical energy is an how cells release it

from food.3. Define calories and kilocalories as units of energy.

Ch. 7.2: Cellular Respiration

Cellular Respiration releases stored chemical energy in food.

Chemical bonds STORE ENERGY (Potential energy).

Respiration Equation (not balanced)

Ch. 7.2: Potential Energy

Energy: Ability to perform work (Work: moving something, making something happen or stop happening).

Potential Energy: Stored energy; due to an object’s position or arrangement.

Object @ top of hill (as you climb higher, against gravity, you gain potential energy; Energy related to position).

Food (energy stored in chemical bonds; Energy related to arrangement of atoms in molecule)

7.2: Potential Energy & Kinetic Energy

Kinetic Energy: Energy of motion

Potential Energy: Stored Energy

Law of Conservation of Energy: Energy within a system is not created or destroyed. It just changes form (Potential <--> Kinetic )

7.2: Chemical Energy•Type of potential energy stored in bonds of molecules

•Based on position arrangement of atoms and # of bonds

7.2: Thermal Energy

Thermal Energy (experienced as heat) cannot be put back into the system to do work. Heat dissipates to the surroundings. Energy that is transformed to heat must be replaced by new supply of energy.

•Type of kinetic energy

•Total amount of energy associated w/ RANDOM MOVEMENT OF MOLECULES.

•Thermal energy that is transferred from warmer to cooler objects = HEAT

Ch. 7.2: Energy Transformation

Potential energy stored in bonds of sugar is released during respiration. The chemical energy that is released is transformed to kinetic energy of motion and thermal energy (heat).

Kinetic energy Thermal energy

Potential energy

Chemicalenergy

7.2: Energy Transformations

Ch. 7.2: Cellular Respiration & Combustion

Both processes break complex molecules into smaller ones that have LESS chemical energy stored in bonds. Energy difference - used to DO WORK!

Respiration:

Combustion:

Gasoline + O2 ---> CO2 + H2O + Energy (motion & heat)

(hydrocarbon)

+ Energy (ATP + heat)

Ch. 7.2: Calories and Energy

calorie: amount of energy used required to reaise the temperature of 1 gram of water by 1 degree C.

Used to measure energy content in food.

“Calorie” = Food calorie = kilocalorie (1 kcal = 1000 calories)

Example: 1 peanut has 5 kcal … the heat from burning 1 peanut would raise the temperature of 1 kg of water by 5 C.

Cells don’t “burn” food -- they break food apart in respiration.

Ch. 7.2: Calories and Energy

Problem:

If a food has 10 kcal (or 10 food calories) of energy, how much could it increase the temperature of 100 g of water?