Analysis 27 - BIOLOGY JUNCTION

Why Boats Float

How does a heavy boat float?

A boat, or any other object designed to float, is based on a theory by a very old guy, even older than Capt. Matt. Though he is old and, by the way, dead, he was really a cool guy and his name was Archimedes (Ark-i’-meed-eez). His principle, cleverly named the Archimedes’ Principle, explains how things float.

If you fill your bathtub with water, what happens when you get in? The water rises, right? (And sometimes goes over the side.) That is because you “displaced” some of the water with your body and it had to go somewhere. The key to floating is that the object must displace an amount of water which is equal to its own weight.

For example, suppose you had a block of wood that was 1 foot square. Let’s say that this block of wood weighs about 50 pounds. Now say we lower that wood into the water. The wood will move down into the water until it has displaced 50 pounds of water. That means that fifty pounds of water are pushing back up on the block and making it float.

The principle of floating is pretty easy, however, if you want to remain inside the boat and actually get where you want to go, your boat must have “stability” as well as being able to float. Stability means that it is designed not to tip over easily. That doesn’t mean it won’t ever tip over.

stability1.jpg (8249 bytes)

On a large ship like an ocean liner or tanker, the movement of one person doesn’t affect the stability of the ship because it was designed to safely carry lots of weight. But on a small boat, like a fishing boat, your weight and the weight of your gear (and where you put it) has an effect on the stability of the boat.

stability2.jpg (11938 bytes)

A boat is said to “heel” (no not the one on your foot) when it leans over to one side. This is why you never want to sit or step onto the side of a boat. Your weight could make it “heel” too much and it may tip over. You should also balance the weight of all the stuff you bring with you. In a small boat, you and your gear should always stay low and to the center of the boat. When getting into a small boat, always try to step into the center and keep “one hand for yourself and one for the boat.”

stability3.jpg (11482 bytes)

Of course, because you have on your PFD and are displacing enough water to float, you would be okay, just a little wet and cold. If this should ever happen to you and you can’t right the boat (turn it back over), stay with the boat, blow your whistle or yell for help.

So . . . the next time someone says “Whatever floats your boat” tell them about Archimedes and stability and why it’s a very good idea to always wear your life jacket!

Tonicity Animations

TONICITY

What is the tonicity of this solution?

What happens to the cell?

What is this called?

What is the tonicity of this solution?

What happens to the cell?

What is this called?

What is the tonicity of this solution?

What happens to the cell?

What is this called?

Animations by Terry Brown – http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

Thumb Wrestling Lab Sample1 Preap

Scientific Method – “I’m All Thumbs”

Introduction:

What makes a “Class Champion” thumb wrestler? Does thumb diameter, length, or wrist diameter have an effect on the overall chances of winning a thumb wrestling match? If you want to find out the answers to these questions then you have to do some scientific study. Scientific study is not only about plants and animals; it is also about how we function. You will have to use the scientific method to answer thesis questions. Scientific method is the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to demonstrate the truth or falseness of the hypothesis, and a conclusion that validates or modifies the hypothesis.

Hypothesis:

The person with the longest thumb will win the thumb war.

Materials:

The materials that were used for this lab was a metric ruler, metric tape measure, scissors, string, and a calculator.

Methods:

First you should choose a partner. Then measure the circumference of your thumb in centimeters at its widest point. Next you measure the length of your thumb, from the tip to the end of its second joint. Then measure the circumference of the wrist over the ulnar knob. Then you copy all of your information on the board onto the table in the results section of the lab.

Results:

Thumb Circumference	Thumb Circumference (cm)	Thumb Length (cm)	Wrist Circumference (cm)	Number of Wins
Cason, Drew	8.4	9	21.5	4
Dittrich, Chad	9	10	24	19
Holt, Brad	8	9.5	21	2
Hooker, Chris	7.1	9.3	21	2
Jones, Jett	8.5	9.8	21	6
Lambert, Scott	9.5	8	23	0
Lewis, Cody	8	9.5	20.5	1
Lockwood, Blake	8.3	8.5	21	0
Lorince, Alan	9.4	9.5	24	1
Moore, Clark	8.5	10	20	1
Phillips, Jaylon	9.3	10	24	1
Simpson, Jonathan	8	8.3	20	0
Smith, Zack	8.3	8.4	22.1	0
Williams, Paul	8.4	8	21	0
Yancey, Jey	9	10	22.5	0

Questions:

1. Restate your hypothesis: The person with the longest thumb will win the thumb war.

2. Which student won? Male: Chad Dittrich Female: Ashley Kersieck

3. What were their measurements: Male: thumb circumference-9cm, thumb length -10cm, and wrist circumference-24 cm.

Female Thumb circumference 7.0, thumb length 8.5, and wrist circumference 20.5

4. What was the mean thumb circumference of the class? 21.0

5. What was the mean wrist circumference of the class? 8.1

6. Did all those with larger measurements win their matches? No

7. Was your hypothesis correct? Yes

8. If not, explain what was different. It was right

9. What is the independent variable? Total of each contestant’s wrist and thumb measurements

10. What is the dependent variable? The number of

11. List the controlled variables in this experiment. Compete only in same sex, and follow all rules.

12. Would this be considered a controlled experiment? No

13. Explain your answer. Their were too many variables

Error Analysis:

The people wrestling might not have followed the rules by picking their arm up when they were wrestling or people just not trying would affect the outcome. Also people might have written their measurements in someone else’s place, which would affect the outcome as well.

Discussion and Conclusion:

The male who won the most thumb wrestling matches, nineteen wins, also had one of the longest thumb lengths, 9.0 centimeters. However, three other males with longer thumb lengths, 10.0 centimeters had fewer wins. Therefore the original hypothesis that the person(s) with the longest thumb length would also have the most wins was incorrect. If the measurements for each person were totaled or averaged together, then the persons with the greatest total measurement or highest average would have had the most wins. The current data would support this hypothesis.

BACK

Transpiration

Transpiration

Introduction:
The amount of water needed daily by plants for the growth and maintenance of tissues is small in comparison to the amount that is lost through the process of transpiration and guttation. If this water is not replaced, the plant will wilt and may die. The transport up from the roots in the xylem is governed by differences in water potential ( the potential energy of water molecules). These differences account for water movement from cell to cell and over long distances in the plant. Gravity, pressure, and solute concentration all contribute to water potential and water always moves from an area of high water potential to an area of low water potential. The movement itself is facilitated by osmosis, root pressure, and adhesion and cohesion of water molecules.

The overall process: Minerals actively transported into the root accumulate in the xylem, increase solute concentration and decrease water potential. Water moves in by osmosis. As water enters the xylem, it forces fluid up the xylem due to hydrostatic root pressure. But this pressure can only move fluid a short distance. The most significant force moving the water and dissolved minerals in the xylem is upward pull as a result of transpiration, which creates a negative tension. The “pull” on the water from transpiration is increased as a result of cohesion and adhesion of water molecules.

The details: Transpiration begins with evaporation of water through the stomates (stomata), small openings in the leaf surface which open into air spaces that surround the mesophyll cells of the leaf. The moist air in these spaces has a higher water potential than the outside air, and water tends to evaporate from the leaf surface. The moisture in the air spaces is replaced by water from the adjacent mesophyll cells, lowering their water potential. Water will then move into the mesophyll cells by osmosis from surrounding cells with the higher water potentials including the xylem. As each water molecule moves into a mesophyll cell, it exerts a pull on the column of water molecules existing in the xylem all the way from the leaves to the roots. This transpirational pull is caused by (1) the cohesion of water molecules to one another due to hydrogen bond formation, (2) by adhesion of water molecules to the walls of the xylem cells which aids in offsetting the downward pull of gravity. The upward transpirational pull on the fluid in the xylem causes a tension (negative pressure) to form in the xylem, pulling the xylem walls inward. The tension also contributes to the lowering of the water potential in the xylem. This decrease in water potential, transmitted all the way from the leaf to the roots, causes water to move inward from the soil, across the cortex of the root, and into the xylem. Evaporation through the open stomates is a major route of water loss in the plant. However, the stomates must open to allow the entry of CO2 used in photosynthesis. Therefore, a balance must be maintained between the gain of CO2 and the loss of water by regulating the opening and closing of stomates on the leaf surface. Many environmental conditions influence the opening and closing of the stomates and also affect the rate of transpiration. Temperature, light intensity, air currents, and humidity are some of these factors. Different plants also vary in the rate of transpiration and in the regulation of stomatal opening.

Exercise 9A Transpiration

In this lab, you will measure transpiration under various laboratory conditions using a potometer. Four suggested plant species are Coleus, Oleander, Zebrina, and two week old bean seedlings.

Materials:
0.1 mL pipette, plant cutting, ring stand, clamps, clear plastic tubing, petroleum jelly, fan, lamp, spray bottle, and plastic bag.

Procedures:
Each lab group will expose one plant to one treatment.

1. Place the tip of a 0.1 mL pipette into a 16 -inch piece of clear plastic tubing.

2. Submerge the tubing and the pipette in a shallow tray of water. Draw water through the tubing until all the air bubbles are eliminated.

3. Carefully cut your plant stem under water. This step is very important, because no air bubbles must be introduced into the xylem.

4. While your plant and tubing are submerged, insert the freshly cut stem into the open end of the tubing.

5. Bend the tubing upward into a “U” and use the clamp on a ring stand to hold both the pipette and the tubing.

6. If necessary use petroleum jelly to make an airtight seal surrounding the stem after it has been inserted into the tube. Do not put petroleum jelly on the end of the stem.

7. Let the potometer equilibrate for 10 minutes before recording the time zero reading.

8. Expose the plant in the tubing to one of the following treatments( you will be assigned a treatment by your teacher):

a). Room conditions.

b). Floodlight (over head projector light).

c). Fan ( place at least 1 meter from the plant, on low speed, creating a gentle breeze).

d). Mist ( mist leaves with water and cover with a transparent plastic bag; leave the bottom of the bag open).

9. Read the level of water in the pipette at the beginning of your experiment(time zero) and record your finding in Table 9.1.

10. Continue to record the water level in the pipette every 3 minutes for 30 minutes and record the data in Table 9.1.

Table 9.1: Potometer Readings

Time (min)	Beginning (0)	v3ss	fff6ff	9	12	15	18	21	24	27	30
Reading (mL)								4nnnnnnn	4nnnnnn	nnnn4

11. At the end of your experiment, cut the leaves off the plant and mass them. Remember to blot off all excess water before massing.

Mass of leaves ______________ grams.

Calculation of Leaf Surface Area
The total surface area of all the leaves can be calculated by using one of the following procedures.

__________________ = Leaf Surface Area (m2)

Leaf Trace Method:
After arranging all the cut-off leaves on the grid below, trace the edge pattern directly on to the grid. Count all of the grids that are completely within the tracing and estimate the number of grids that lie partially within the tracing. The grid has been constructed so that a square of four blocks equals 1 cm2. The total surface area can then be calculated by didvding the total number of blocks covered by 4. Record the value above.

Grid 9.1

Leaf Mass Method:

Cut a 1 cm2 section of one leaf.
Mass the 1 cm2 section.
Multiply the section’s mass by 10,000 to calculate the mass per square meter of the leaf. (g/m2) ____________
Divide the total mass of the leaves (step 11) by the mass per square meter (above). This value is the leaf surface area.
Record this value above.

12. Water lost per square meter: To calculate the water loss per square meter of leaf surface, divide the water loss at each reading (Table 9.1) by the leaf surface area you calculated.

Table 9.2: Individual Water Loss in mL /m2

Time Intervals ( minutes)
s	0-3	3-6	6-9	9-12	12-15	15-18	18-21	21-24	24-27	27-30
Water Loss (mL)
Water loss per m2

13. Record the averages of the class data for each treatment in Table 9.3.

Table 9.3: Class Average Cumulative Water Loss in mL /m2

Time ( minutes)
Treatment	0	3	6	9	12	15	18	21	24	27	30
Room	0
Light	0
Fan	0
Mist	0

14. For each treatment, graph the average of the class data for each time interval. You may need to convert data to scientific notation. All numbers must be reported to the same power of ten for graphing purposes.

Graph Title________________________________________

Graph 9.1

Analysis of Results:
1. Calculate the average rate of water loss per minute for each of the treatments:

Room: ______________________________________________________________________

Fan: _______________________________________________________________________

Light: _______________________________________________________________________

Mist: _______________________________________________________________________

2. Explain why each of the conditions causes an increase or decrease in transpiration compared to the control.

Conditions	Effect	Reasons
Room
Fan
Light
Mist

3. How did each condition affect the gradient of water potential from stem to leaf in the experimental plant?

_______________________________________________________________________

4. What is the advantage to a plant of closed stomata when water is in short supply? What are the disadvantages?

_______________________________________________________________________

5. Describe several adaptations that enable plants to reduce water loss from their leaves. Include both structural and physiological adaptations.

_______________________________________________________________________

6. Why did you need to calculate leaf surface area in tabulating your results?

________________________________________________________________________

Sucrose Hydolysis by Sucrase

Sucrose Hydrolysis Using Sucrase

INTRODUCTION:

In this lab, you will demonstrate the production of the enzyme sucrase (invertase) by yeast. The enzyme sucrase catalyzes the hydrolysis of the disaccharide sucrose to invert sugar. Invert sugar is a mixture of glucose and fructose, which are both monosaccharides. Yeast cannot directly metabolize (ferment) sucrose. For the yeast to utilize sucrose as an energy source, it must first convert it to the fermentable monosaccharides glucose and fructose.
Benedict’s solution is a test reagent that reacts positively with simple reducing sugars. All monosaccharides and most disaccharides are reducing sugars, possessing a free carbonyl group (=C=O). Sucrose is an exception in that it is not a reducing sugar. A positive Benedict’s test is observed as the formation of a brownish-red cuprous oxide precipitate. A weaker positive test will be yellow to orange. Both glucose and fructose test positive with benedict’s solution, sucrose does not.

MATERIALS NEEDED:

*Yeast filtrate solution
one 7 gram package active dry yeast per 80 mL distilled water
Ring stand and ring to hold funnel
Filtering funnel
Filter paper (fast speed)
**5% sucrose solution
5 grams sucrose per 95 mL distilled water
***5% glucose (dextrose) solution
5 grams dextrose per 95 mL distilled water
Benedict’s qualitative solution
Distilled water
Five 10-mL graduated cylinders (one for each solution)
7 test tubes 18 x 150 mm
Test tube holder
Test tube rack
2 400-mL beakers
Hot plate

PRE-LAB:

* To prepare a yeast filtrate solution, mix one package of active dry yeast with 80 mL of distilled water. Let stand for 20 minutes, stirring occasionally. Filter the resulting suspension and save the filtrate solution. This is your invertase extract. Refrigerate the extract if held overnight. Approximately enough for 8 labs.

**To prepare a 5% sucrose solution, dissolve 5 grams of sucrose in 95 mL of distilled water. This should be prepared shortly before use. Approximately enough for 4 labs.

***To prepare a 5% glucose solution, dissolve 5 grams of dextrose (this is the name used when dry) in 95 mL of distilled water. This should be prepared shortly before use. Approximately enough for 9 labs.

PROCEDURE:

1. Label 3 test tubes A1, A2, and A3, and place in the test tube rack. Place into the test tubes as follows:

10 mL

Into tube A2, place 10 mL of 5% sucrose solution and 4 mL of invertase extract.

Into tube A3, place 10 mL distilled water and 4 mL of invertase extract.

Thump the tubes to mix.

2. Put approximately 250 mL of 30 to 35 oC water into a 400-mL beaker. Incubate the three tubes in this warm water bath for 35 minutes.

3. Label 4 test tubes B1, B2, B3 and B4, and place in the test tube rack. Place 5 mL of Benedict’s qualitative solution into each tube. Now transfer to the B tubes as follows:

Into tube B2, transfer the contents of tube A2.

Into tube B3, transfer the contents of tube A3.

Into tube B4, place 10 mL of 5% glucose solution.

Thump the tubes to mix.

4. Place tubes B1, B2, B3, and B4 into a boiling water bath. CAUTION: do not let the bath boil hard. Keep it just at the boiling point. After 3 or 4 minutes, remove the tubes and note whither any change is evident.

QUESTIONS AND OBSERVATIONS:

1. Did tube B1 test positive or negative?

2. What does this show?

3. Did tube B2 test positive or negative?

4. What does this show?

5. Did tube B3 test positive or negative?

6. What does this show?

7. Did tube B4 test positive or negative?

8. What does this show?