Biology Ch 5 Review

PhotosynthesisCellular Respiration

Biology Ch 5 Review

Directly, or indirectly, almost all energy for living things comes from the sun.

1. Plants convert light energy to chemical energy through photosynthesis;

2. animals consume the plants,3. other animals consume the smaller

animals, 4. we consume the larger animals.

We call this the “flow of energy through the system” because energy that starts with the sun moves to us eventually as food, passing through all the intermediate steps in the system.

Biology Ch 5 Review

Metabolism involves either using energy to build molecules, or breaking down molecules in which energy is stored. Our metabolism involves breaking down the food we eat for our energy.

Autotrophs are organisms that use energy from sunlight to make organic compounds.

All plants that carry out photosynthesis are autotrophs. Autotrophs are the producers of the system; producing all food at the start of the energy chain.

Biology Ch 5 Review

Autotrophs, especially plants, are photosynthetic organisms.

Photosynthetic organisms

1. Take in carbon dioxide (CO2) and water (H2O)

2. Use the energy from sunlight as a power source to create a reaction

3. Convert the carbon dioxide + water into food for the plant in the form of a sugar called glucose

4. Give off oxygen as a product of this reaction

Carbon dioxide + waterenter the plant

Sugar in the form of glucose is created

Oxygen is the byproduct that gets released in the process

Biology Ch 5 Review

Heterotrophs are organisms that must get energy from food instead of directly from sunlight.

We (humans) are Heterotrophs because we get our energy from food through the process of cellular respiration.

Heterotrophs are consumers in the food chain. We consume food molecules but do not produce any.

Heterotrophs that eat only the “producers” in the form of plants are called herbivores (plant eaters) and are primary consumers in the food chain.

Biology Ch 5 Review

Cellular respiration is a process similar to burning fuel.

Cellular respiration is a metabolic process which releases the energy in food to make ATP.

This ATP provides cells with the energy they need to carry out cellular activities.

Biology Ch 5 Review

When cells break down food molecules, some of the energy in the molecules is released as heat.

Most of the remaining energy is stored temporarily in molecules of ATP.

ATP is like a rechargeable battery that can take a charge, hold it, and deliver it’s energy to other locations in the cell when needed at a later time.

The energy released from ATP can be used to start other chemical reactions, such as those that build molecules.

Biology Ch 5 Review

Photosynthesis is the process by which a plant makes food for it to grow.

Plants, through photosynthesis:

take IN water and carbon dioxide as the raw ingredients,

Make food (sugars) with it using energy from the sun,

and put OUT oxygen as a byproduct of the process

Biology Ch 5 ReviewPhotosynthesis has three stages

1. Energy is captured from sunlight

2. Light energy is converted to chemical energy, which is temporarily stored in ATP. This powers the process.

3. The chemical energy stored in ATP powers the formation of glucose, using carbon dioxide and water.

Glucose, a form of sugar, provides the food that plants use to survive and grow.

Biology Ch 5 Review

Photosynthesis requires the following 4 things:

1. Carbon Dioxide2. Water 3. Light Energy from sunlight4. Chlorophyll

Carbon Dioxide enters the plant through small pores on the bottoms of leaves called stomata. Carbon dioxide combines with water to create the glucose sugars that the plant uses for it’s food.

Biology Ch 5 Review

Water (H2O) is the other ingredient that is used by all plants in photosynthesis.

Water is drawn up into the plant through the roots, up the stem and into the leaves where photosynthesis occurs.

Sunlight is the main ingredient that powers the process. Sunlight is where the energy comes from originally to convert the water and carbon dioxide into sucrose 5-carbon sugars.

Biology Ch 5 Review

Plants trap sunlight energy with chloroplasts and use the energy to power the process of photosynthesis.

Chloroplasts are found within the cells of all plants, giving the leaves of plants their green color.

Chlorophyll is the chemical in chloroplasts that reacts to sunlight. Chloroplasts are inside the cells of all plants.

Chloroplasts in plant cell

Biology Ch 5 Review

Pigments are light absorbing substances that absorb only certain wavelengths and reflect all others.

Chlorophyll, the primary pigment involved in photosynthesis, absorbs mostly blue and red light and reflects green and yellow.

This reflection of green and yellow gives plants their green appearance.

Chloroplasts in plant cell

Biology Ch 5 Review

4 factors that affect photosynthesis:

1. Light: The more sunlight a plant gets, the faster photosynthesis will happen.

2. Water: Plants require water for photosynthesis. If there is not enough water, photosynthesis slows down or stops.

3. Temperature: Temperature range affects photosynthesis. Too high or too low a temperature will slow down or stop the enzymes that help make parts of the process happen.

4. CO2: The amount of Carbon Dioxide (CO2) available affects photosynthesis. The more CO2 available, the faster photosynthesis will occur.

Biology Ch 5 Review: process of photosynthesis

1. sunlight strikes a thylakoid in a cell, light energy is transferred to electrons in chlorophyll.

2. Water (H20) is split in the process releasing hydrogen ions and oxygen (O2) as a byproduct of the process.

3. Exited electron moves through “electron transfer chains” producing hydrogen ions.

4. Hydrogen ions enter cell, combine with ADP to create ATP. Electron transfer chain provides energy that catalyzes this reaction. Also combine with NADP + H to create NADPH.

5. In Calvin Cycle, CO2 + ATP + NADPH 5 carbon sugars

(glucose) Part of the glucose goes back into the

cycle making it happen again so more glucose is created.

Biology Ch 5 Review: Cellular Respiration

Most of the foods we eat contain energy stored in proteins, carbohydrates, and fats. Before our cells can use this energy it must be transferred to ATP within the cells.

Cells transfer the energy in organic compounds to ATP through a process called cellular respiration.

Oxygen in the air you breath makes the production of ATP more efficient.

Metabolic processes that require oxygen are called aerobic processes. Metabolic processes that require NO oxygen are called anaerobic processes.

Biology Ch 5 Review: Cellular Respiration

The energy-producing process in living things is called respiration. Respiration is the release of energy by combining oxygen with digested food (glucose).

Carbon dioxide and water are also produced as byproducts. They are the waste products of respiration.

A simple formula to show respiration looks like this:Glucose + oxygen carbon dioxide (waste) + water (waste) + energy

Biology Ch 5 Review: Cellular Respiration

The primary fuel for cellular respiration is glucose which is formed when carbohydrates such as starch and sucrose are broken down.

Cellular respiration occurs in three major stages

Stage 1: glucose is converted to pyruvate producing a small amount of ATP and NADH.

1. Glycolysis uses two ATP molecules

2. but produces four ATP molecules in return.

3. Thus, we gain two ATP molecules for a gain ratio of 2 to 1.

Biology Ch 5 Review: Cellular Respiration

Glycolysis is followed by another set of reactions, involving the Krebs Cycle, that uses the energy temporarily stored in NADH to make more ATP.

Stage 2: Aerobic respiration occurs: this is when oxygen is present, pyruvate and NADH make more ATP.

The Krebs Cycle is a series of reactions that produce energy-storing molecules during anaerobic respiration.

Biology Ch 5 Review: Cellular Respiration

Stage 3: In an electron transfer chain, continuing reactions create a large amount of ATP from the materials from stage 2.

Most of a cell’s ATP is made during this aerobic respiration. (requiring oxygen)

For each molecule of glucose that is broken down, as many as two ATP molecules are made directly during the Krebs cycle, than. . .

and up to 34 more ATP molecules are produced later by the electron transport chain. The presence of oxygen makes this production much more efficient thus so much more ATP is produced.