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Transcription:

The amount of water in the blood must be kept more or less the same all the time to avoid cell damage as a result of osmosis.

This balance is achieved by the action of the hormone ADH. When the body is losing too much water, the hypothalamus detects that there is not enough water in the blood and sends a message to the pituitary gland, which releases ADH. ADH travels in the blood to the kidneys and affects the tubules so more water is reabsorbed into the blood. As a result the body makes smaller volume of more concentrated urine. The level of water in the blood increases until it is back to normal.

Sometimes the level of water in the blood goes up because the body has not been losing any water, or the body has been taking in a lot of water. The hypothalamus detects the change and sends a message to the pituitary. The release of ADH into the blood is slowed down or even stopped. Without ADH the kidneys will not save as much water and will produce large volumes of dilute urine. The level of water in the blood falls back to the normal level.

The secretion of ADH is an example of negative feedback. As the level of water in the blood falls, negative feedback ensures that the amount of ADH rises. As the level of water in the blood rises, negative feedback ensures that the amount of ADH falls. ADH has a simple neurohormone pathway because the hypothalamus detects the change and pituitary secrets ADH directly. ADH is composed of peptides. As a result, it is water-soluble and cannot pass through the cell membrane. Therefore, the receptor for ADH is located on cell membrane.

 Work Cited

CourseNotes.http://www.coursenotes.org/Biology/Outlines/Chapter_45_Hormones_and_the_  Endocrine_System. Web.

Quizlet. http://quizlet.com/5386280/endocrine-glands-and-hormones-flash-cards/. Web.

The Influence of Sucrose Concentration on Yeast Cell Respiration Lab

Roxanne Zong

Mr. Quick

D Block

02/09/14

The Influence of Sucrose Concentration on Yeast Cell Respiration

Abstract:

I suppose that if the temperature, the amount of yeast and the amount of O₂ are constant, the higher sucrose concentration is, the higher the rate of yeast cell respiration will be. The result shows that when there is 0.1g sugar in the system, the rate of yeast cell respiration is about 0.21326ml/min. When there is 1g sugar in the system, the rate of yeast cell respiration is about 0.86677ml/min. When there is 3g sugar in the system, the rate of yeast cell respiration is about 0.37591ml/min. When there is 5g sugar in the system, the rate of yeast cell respiration is about 0.80234ml/min. However, the rate at 12.17% concentration is an error. As a result, the rate of yeast cell respiration increases as the concentration of sucrose increases.

Introduction:

            Cell respiration happens in mitochondria, wherein C₆H₁₂O₆, oxygen and ADP⁺ react and produce ATP, which provide energy for activities: C₆H₁₂O₆ + 6O₂ à 6CO₂ + 6H₂O + 36/38ATP. A lot of factors can affect the rate of cell respiration, such as pH value and temperature. The purpose of this lab is to explore if the concentration of sucrose has an influence on yeast cell respiration. My hypothesis is that if the temperature, the amount of yeast and the amount of O₂ are constant, the higher sucrose concentration is, the higher the rate of yeast cell respiration will be.

Material:

Four syringes, four tubes of equal lengths, four stoppers, four test tubes, a block of Styrofoam with four holes on it that can fit the test tubes, yeast, warm water, salt, sugar, four graduate cylinders.

Procedure:

1.     Add 1g of yeast, 0.1g of salt into all four test tubes.

2.     Add 0.1g, 1g, 3g, and 5g sugar into respective test tubes and label them.

3.     Measure 35ml warm water with the four graduate cylinders and add water into the four test tubes at the same time.

4.     Put on stoppers and shake the four test tubes.

5.     Remove stoppers and place test tubes in the four holes in the Styrofoam. Leave the contents of the test tubes exposed to air for 5 minutes.

6.     After 5 minutes attach the four test tubes with the four tubes and the four syringes. Make sure the corks of the syringes stop at 2ml before attaching.

7.     Push the corks of syringes and read the amount of gas within the system every 1 minute and repeat 5 times.

 Results:

Time/min	Start	1	2	3	4	5
0.1g	0.13ml	0.1ml	0.1ml	0.2ml	0.3ml	0.3ml
1.0g	1.0ml	1.0ml	2.1ml	3.0ml	4.4ml	6.0ml
3.0g	3.0ml	3.8ml	4.8ml	7.4ml	10.2ml	11.2ml
5.0g	2.2ml	3.0ml	3.2ml	4.1ml	6.1ml	8.2ml

The amount of gas produced each minute:

Time/min	Start	1	2	3	4	5
0.1g	0ml	-0.03ml	0ml	0.1ml	0.1ml	0ml
1.0g	0ml	0ml	1.1ml	0.9ml	1.4ml	1.6ml
3.0g	0ml	0.8ml	1ml	2.6ml	2.8ml	1ml
5.0g	0ml	0.8ml	0.2ml	0.9ml	2ml	2.1ml

            When there is 0.1g sugar in the system, the rate of yeast cell respiration is about 0.21326ml/min. When there is 1g sugar in the system, the rate of yeast cell respiration is about 0.86677ml/min. When there is 3g sugar in the system, the rate of yeast cell respiration is about 0.37591ml/min. When there is 5g sugar in the system, the rate of yeast cell respiration is about 0.80234ml/min.

Mass of water: 35ml• 1g/ml=35g

Concentration of sucrose in each system:

0.1g/(1g+0.1g+35g+0.1g)•100%=0.28%

1g/(1g+1g+35g+0.1g)•100%=2.70%

3g/(1g+3g+35g+0.1g)•100%=7.67%

5g/(1g+5g+35g+0.1g)•100%=12.17%

The rate of yeast cell respiration generally increases as the concentration of sucrose increases. The rate is supposed to continue to increase after the concentration reached 7.67%, but the last data of the graph was extremely small and was likely because the sugar in the system was nearly finished. When the sugar concentration reached 12.17%, the rate was lower. There might have been a leak in the system, so the rate decreased.  

Conclusion:

            When temperature, the amount of yeast and the amount of O₂ are constant, the rate of yeast cell respiration increases as the concentration of sucrose increases. In the result, the readings of the syringes show the amount of CO₂ each system produces. According to the equation C₆H₁₂O₆ + 6O₂ à 6CO₂ + 6H₂O + 36/38ATP, the more CO₂ a system produce in a certain amount of time, the more ATP it produces in this amount of time and the bigger the Compared to the control’s rate 1.0314ml/min, sucrose concentration of 0.28% has a lower rate of 0.0443ml/min. The sucrose concentration of 2.70% has a higher rate of 0.867ml/min. A potential error in this lab can be that there is a leak in the 12.17% concentration system so that some CO₂ leaked out, and it leads to the calculation that shows that there is a lower rate in the 12.17% concentration. Another error is that the tube for sucrose concentration 0.28% was broken, but I did not find out this until the third minute. As a result, I redid the first two minutes by doing an extra two minutes’ reading for the 0.28% one, and the sucrose in the test tube was finished in the last two minutes. Therefore, the rate of concentration 0.28% should have been bigger than what is shown in the result.

Work Cited List

Knapp Holtzclaw, Theresa. “Cell Respiration.” Pearson Education, Inc. Web.