Tuesday, November 1, 2011

Need a pencil for checkup- Plan:1) Checkup part 1 and part 22) Cricket and Yeast Labs3) Cellular Respiration Intro worksheet

Checkup

• Do not write anything on scan-tron yet…• Record name and FORM A or B - under School Name- When finished with checkup- raise your

hand- complete OPEN LogBook Check part of Checkup

- READ the directions for Part 2 carefully

Planner

• Homework: Finish Cellular Respiration Introduction worksheet for Block Day

Make an entry: O2 and CO2 in animals and yeast-11/1 • You have see that when sugar is burned, oxygen

levels decrease and carbon dioxide levels increase.

• If you placed animals in a closed container, what do you think would happen to the levels of oxygen and carbon dioxide in the container? Explain your reasoning.

• Oxygen (O2) levels would decrease and CO2 levels would increase because crickets are “breathing”.

It is difficult to “see” what is happening inside a cell, especially when the cell is often just one of over a trillion cells that make up a large multicellular organism like humans.However, we can study the whole organism and infer that the changes we see at the organismal level are also occurring at the cellular level.

Collecting and interpreting evidence

• In this experiment, we will focus on how changes in O2 and CO2 levels might provide evidence for our initial ideas. We will measure O2 and CO2 levels in the air inside a container containing crickets.

• Observe the crickets in their container. Is there any evidence about what they have been eating? If so, what have they been eating?

Cricket food • Based on your knowledge of food molecules,

what main type of food molecule will you be testing?

Glucose (carbs)

02 AND CO2 LEVEL WITH CRICKETS AND FOOD IN THE CONTAINER

Yeast is a single- celled organism whose cells are similar to our own in many ways.

02 AND CO2 LEVEL WITH YEAST AND FOOD IN THE CONTAINER

CC

WITH SUGAR

02 AND CO2 LEVEL WITH YEAST AND FOOD IN THE CONTAINER

CC

WITHOUT SUGAR

What does the data mean?

The yeast breaks down the sugar to release energy, using O2. -- CO2 was produced.This is similar to when sugar burns.

Make an entry- Cellular Respiration Introduction-11/1

• Scientists have found that the much of the sugar in cells ultimately ends up as carbon dioxide and water in a process that also requires molecular oxygen.

(Think about our discussion the other day—you have eaten thousands of pounds of food—but most of it isn’t in your body anymore)

• This process is called cellular respiration and can be summarized using the same chemical equation that we used to represent the burning of sugar.

O2 + C6H12O6 => CO2 + H2O

• 1) What evidence did you find that cellular respiration is taking place in animal cells?

The O2 concentration decreased and the CO2

concentration increased in the cricket container. The crickets also had food that contained glucose

6O2 + C6H12O6 => 6CO2 + 6H2O• Notice that this is exactly the same

equation that we used when we considered the actual proportions of molecules being consumed and produced when sugar is burned.

• 2) Given that the above equation is an accurate representation of cellular respiration, are any atoms destroyed in the process of cellular respiration? What is your evidence?

• 3) What do you think would be the benefit of the process of cellular respiration to living cells?

No matter is destroyed—the same number of atoms exist before and after the reaction.

The chemical energy contained in glucose is being released to power cells.

ENERGY

GLUCOSE

CHEMICAL ENERGY

OXYGEN (O2)

CO2

H2O