Cell Energy Worksheet

Associate Program Material – Heather Earnhardt

Cell Energy Worksheet

Answer the following questions:

Cellular respiration:

What is cellular respiration and what are its three stages?

Cellular respiration is the process by which electrons are transferred between glucose to coenzymes and then to oxygen. NTP is made by the relocation of electrons. The end result of the process is the carbon dioxide and water that are released as byproducts of the process.

The three stages are: glycolysis, citric acid cycle, and electron transport.

What is the role of glycolysis? Include the reactants and the products. Where does it occur?

Glycolysis is the sugar splitting process where the molecule is split in half outside of the mitochondria. The molecule NAD+ picks up electrons and hydrogen atoms from the carbon molecule and become NADH. ATP is produced from the process, as well as pyruvic acid. Glycolysis can occur with or without oxygen. With oxygen it is the first stage of the cellular respiration, but if the process is done without oxygen it is called fermentation.

What is the role of the citric acid cycle? Include the reactants and the products. Where does it occur?

The Citric Acid Cycle starts after the glycolysis cycle produces the acetyl CoA compound. The Coenzyme A is removed and the remaining carbon skeleton is attached to another 4-carbon molecule. The new 6-carbon chain releases carbon dioxide. Two ATP’s are produced during this process for each molecule of glucose. The end result of the citric acid cycle is 4 CO molecules, 6 NADH molecules, 2 ATP molecules and 2 FADH2 molecules. The process is part of the conversion of carbs, fats, and proteins into carbon dioxide and water; which is usable energy.

What is the role of the electron transport system? Include the reactants and the products. Where does it occur?

The electron transport is the delivery of electrons through a chain of electrons in the membrane of the mitochondria. Electrons are transported along the chain and as they move along the chain they lose energy. The oxygen a person breathes pulls electrons from that chain and water is formed because of it. The energy released relays hydrogen ions across the membrane and creates a high hydrogen ion area. The hydrogen ions speed through the membrane and produces ATP.

Photosynthesis:

What is the overall goal of photosynthesis?

Photosynthesis is the process through which sunlight and carbon dioxide is changed into sugar and oxygen for food in plants. The carbon dioxide is strained into pores in the leaves and into the cells of the plant. The cells filter the carbon dioxide into the chloroplasts, which convert the light to make carbon dioxide and water into sugar and oxygen.

Because photosynthesis only occurs in plants, why is it essential to animal life?

Through the food chain, animals eat plant life and gain nutrients from it for survival. If certain animals couldn’t get the food they need, then the animals that prey on these plant eaters wouldn’t have food either. Plants are essential to sustaining life in the food chain. Photosynthesis also helps because oxygen is produced, which is essential for most of life on earth.

What is the role of the light reactions? Include the reactants and the products. Where does it occur?

The light reactions are the first step of the photosynthesis process by which light is absorbed into the chloroplasts. Inside the chloroplast, there are flattened sacs called thylakoids. The energy is converted into a chemical energy process. The photosystems, which are made of protein and chlorophyll, capture light energy and are connected by an electron transport chain. The photosystem absorbs the light energy and makes the electrons super active. The electrons are replaced by electrons striped from water and create oxygen. The energized electrons go down the transport system and release energy that pumps hydrogen ions into the thylakoid. ATP and NADPH are produced and are used to make the sugar in the Calvin cycle.

What is the role of the Calvin cycle? Include the reactants and the products. Where does it occur?

The Calvin cycle takes place in the thick fluid of the chloroplast called the stroma. Carbon dioxide molecules combine with RuBP molecules. They go through a series of reactions and the sugar molecules, called G3Ps, are rearranged back into RuBPs. G3Ps can be used to build glucose or sucrose. Both are types of sugars that can be broken down into ATP’s necessary for plant growth or other tasks. The Calvin cycle is essential for sugar creation for fuel in the photosynthesis process.

Summary:

Explain how photosynthesis and cellular respiration are linked within ecosystems.

Photosynthesis and cellular respiration both generate molecules that are used between processes. The ecosystems need both processes because both processes work together to keep life going. The cellular respiration of organisms exhales carbon dioxide, which is then used by photosynthesis as a fuel to create the oxygen necessary for life.

Visit the NASA website (http://data.giss.nasa.gov/gistemp/graphs/) and research global temperature changes. How has global warming affected overall temperatures? What effects do cellular respiration and photosynthesis have on global warming?

Global warming is an increase in average temperatures across the air, surface and oceans around the globe. When greenhouse gases trap heat and light, the temperatures across the globe rise. The ecosystems are threatened because species of plants and animals can’t adapt to the rising temperatures and end up dying out. There is an increase in CO2 gases and the cellular respiration/photosynthesis processes become unbalanced. For the processes to work in harmony, both the animals that exhale carbon dioxide and the plants that take the CO2 gas and convert it into oxygen must equally contribute. If the plants die out, the animals will not get enough oxygen to survive. If a plant dies, the animal that eats it will die and so will the animal that preys on that plant eater. The balance between cellular respiration and photosynthesis must be preserved.

REFERENCES:

About.com. (2012). Cellular Respiration. Retrieved from http://biology.about.com/od/cellularprocesses/a/cellrespiration.htm

BioFlix. (2008). http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?eb4respiration [Multimedia]. Retrieved from BioFlix, SCI230 website.

BioFlix. (2008). http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?eb4photosynthesis [Multimedia]. Retrieved from BioFlix, SCI230 website.

GISS Surface Temperature Analysis. (2012). Retrieved from http://data.giss.nasa.gov/gistemp/graphs_v3 /

References: About.com. (2012). Cellular Respiration. Retrieved from http://biology.about.com/od/cellularprocesses/a/cellrespiration.htm BioFlix. (2008). http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?eb4respiration [Multimedia]. Retrieved from BioFlix, SCI230 website. BioFlix. (2008). http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?eb4photosynthesis [Multimedia]. Retrieved from BioFlix, SCI230 website. GISS Surface Temperature Analysis. (2012). Retrieved from http://data.giss.nasa.gov/gistemp/graphs_v3 /