February 8, 2010
Lab handins for Wednesday
A couple points for those preparing their graphs for Wednesday (and all of the material is due W, not M): Our results consist of just 3 numbers (converted to the right units, of course). The X axis is the treatment, so what we have here is a bar graph. Just put the treatment labels in col 1 and the rates in col 2.
For your abstract, the best way to look at your rates is to take the control as 100% and have treatments that transpired less than that as being less than 100% (say, 75%). Similary, those that transpired more will have numbers more than 100%. This way a hurried reader will not make the mistake of seeing "60% less than" and bigger than "20% more than".
I should be in the lab T afternoon until my class at 2, then briefly after class gets out at 3:15.
Posted by bergv at 1:44 PM
February 3, 2010
Rest of test topics
Macronutrients and how they are used by the plant
Examples of micronutrients and how they are used by plant
Essential minerals
Ways we study mineral nutrition
mineral deficiencies, sufficiency, toxicity
soil particles/soil particle surfaces/water/plant--the route of uptake and resupply
all labs
favorite WR stories
Posted by bergv at 8:40 PM
February 1, 2010
Most topics for Test 1
Properties of liquids and solids
Adding negative and positive numbers
Bulk flow vs osmosis
Cell wall vs membrane
Pressure potential
Solute potential
The Water Potential Equation (write it out on test)
Osmotic pressure vs osmotic/solute potential
Evidence for water under tension
All labs to date (lab skills, plant parts, tissue & cell water relations, not G&D or computer skills)
Water loss/gain between cells, cells & solutions
Matric potential
Normal values of water potential factors and WP in plants, soil, air, seeds
Why live cells don’t have negative pressures
Gravitational potential
Xylem structure & function
How air/soil drive transpiration (numbers here)
Capillaries in holding water in xylem wall pores
Embolisms formed by air entering xylem through these pores
Transpiration (geography, biology, chemistry, physics)
Why don’t plants dry out in the air?
What controls stomatal movement (3 things)
Wilting (“permanent,” “temporary:” what, how different)
Why water goes into cells
Guttation
Root pressure
Maple story
Hydraulic lift
Favorite water relations stories (download)
Mangroves
Osmotic adjustment
Refilling embolisms
Hydraulic lift
Apoplastic, symplastic and transcellular water paths
Apoplast (2 parts)
Symplast
Endodermis (location, structure, function)
What the endodermis does for the plant
Route of water flow through root into xylem
Factors that determine water uptake
How the plant controls its water loss
What plants are made of
Macronutrients and micronutrients (start of latter)
(last class not included: it will be listed Wednesday or Thursday)
The best small thing you can do for your studying for this course is to go through the notes as you go along, listing the important topics and points as you go. I make up the test from my list.
Posted by bergv at 1:36 PM
Project Submissions
Here are some hints for you, based on what was turned in so far:
You will need a title page with the project title and your name and class and date. Now is a good time to make this. You can use the same one (except changing the plant) for corn & for beans, although if you want a fancy background, you might want to change it, too.
No pictures from sources other than your own plants are allowed (i.e., no web pictures).
If you want very early pictures of the inside of seeds, you can soak them for a day (any temperature will probably do, and split or cut them apart.
Use the web for labeled images to learn from. You probably want about 7-10 parts labeled on corn, and maybe just a couple fewer on beans.
Label things only once, when they first appear. Just label visible things, not things inside.
No narration is needed now, but you will need it at some time, so now wouldn't hurt. You can always change it later if you want.
You'll need those weights some time soon.
Crop out the ruler if possible, or put areas of copied background over it.
If you have further questions, just ask (or email), and if the questions seem of general interest, I'll post them (no names) and the answers here.
Posted by bergv at 1:25 PM
First test coming up
People are always curious about test structure, so here it is...
20 questions of equal value, though some are longer or more difficult than others.
Every kind of question: multi-sentence explanations, single sentence interpretations or explanations, similarity/difference, what if?, fill in blanks, matching, multiple multiple choice (check all that are true). No definitions.
You should have done a lot of your test studying over the weekend. If not, start today. See the web material (class website) for extra ideas. Remember to ask and answer questions, not just repeat and recite from you notes. You aren't parrots.
More here later today.
Posted by bergv at 8:39 AM
January 28, 2010
Image J available in lab
Image J has been fixed by the computer people (I do not have authorization to mess with programs), and should work on the lab computers. I'll be there Friday afternoon until almost 3 (or later, if needed after my 3 pm appointment) to help people with graphing, images or measurements.
Posted by bergv at 9:21 PM
January 26, 2010
Where's the camera?
It's helpful to get your own images from the camera in advance of lab, if you have time. Some people also have the whole set available to copy from. The fastest thing is to just copy the whole set, then pull your own out of that.
The camera is in the drawer with the Kim-wipes, at the back. Please return it to that spot--it has my Machu Picchu pictures, never mind my camera.
See you tomorrow.
Posted by bergv at 9:32 PM
Feedback on Problem Set #1
Most people did very well on this problem set, and probably had a lot more confidence at the end. Some people came for a little help, and had the same experience.
If you had problems, you probably had lots of problems, such as forgetting that anything actively wet (cells, salty water, xylem) has a matric potential of zero. Probably going through the animated powerpoint a couple of times will get you on track. If not, see me...but do the PPT first.
Posted by bergv at 9:30 PM
January 24, 2010
Feedback on Quiz 1
This is the feedback for Quiz 1, more extensive than it is possible to write on all the individual papers. It also allows people to benefit from the explanations aimed at others' mistakes.
One thing you have to be careful of in a class like this is precision in word use, because each word has a different meaning than its close cousins. It is important to distinguish matrix from matric from matric potential. People who have difficulties in this area should develop a personal vocabulary and use these to make concept maps (see the help link at the study ideas link on the class home page). The problem here is really understanding the meaning; without this understanding you can't give a clear answer.
A general problem people have is failing to answer the question asked. DNAQ = does not answer question asked. If this is your problem, you might highlight or underline the key parts of a question. A number of people gave characteristics of, say, a membrane, but did not say how it contributes to turgor pressure. It's a little like taking your car in to get the tires rotated, and finding that they have replaced your brake pads. Wheels, yes, but not what you asked for. I am a little forgiving on the first quiz, but less so as the course gets along.
1. Molecules of liquids are attached (attracted) to each other, so when you pull or push on one, it pulls or pushes the ones attached to it. Molecules of gases are loners, with no attraction to each other, so while you can push one with another, they are not attached, so you can not pull one with another.
2. Everyone moved the water the right way. Good arithmetic.
3. Solute and matric potentials share the fact that they both lower water potential and the fact that they both are due to chemical (or electrostatic) attraction between water and other molecules/ions. They are different in that solute potential extends uniformly throughout the solution, while matric potential has an effect (value other than zero) only next to a surface (matrix), and doesn't extend through a system.
4. Lots of people didn't do a good job at actually answering the question here, which was about how each element actually aids in establishing turgor pressure. The wall is critical because putting more water in a stretchy membrane won't do a thing unless the volume of the membrane is kept the same by the inelastic (not rigid) wall. The solutes are what lower the water potential so water will move into the cell, pressing the membrane against the wall. The membrane is important because it is what actually pushes against the wall, and keeps the solutes in (we'll see how they get there next month) so the water stays in, even at high pressure.
5. An andvantage of bulk flow is that it can move lots of stuff large distances fast. An advantage of osmosis is that it can move water into cells without moving everthing else in with it, Lots of people had trouble with actually giving an advantage here, rather than just saying something about bulk flow, and something they knew about osmosis.
Grades were OK on this quiz: 3 @ 23/25, 3 @ 22/25, 1 @ 21/25, 2 @ 20/25, 1 @ 18/25. Many of the lower scores were due to not answering the question asked.
Posted by bergv at 4:12 PM
January 21, 2010
Taking photos, finding photos
There is a class in MSH 75 on TTh mornings. You can enter and walk past the sink back to the germinating seeds to take pictures, make observations and take weights. Otherwise, nobody else is using this classroom.
If it's locked (and we're trying to keep it unlocked, though not advertising the fact), you can ask anyone with a key (faculty, custodian) to let you in.
There should be plenty of space on the memory card, but if you need to, you can erase the non-PP pictures.
Remember that for your growth & development project, you will be describing everything that happens to your germinating seeds. Personal observations work well for texture, hardness, color, etc. The images are better for measurements.
We'll spend some time having you actually do measurements on these images in lab next week. In the mean time, you could follow the instructions and use ImageJ on your own. Then you become a teacher in lab, which is good for you and good for your partner. Better yet, think about getting together with you partner and figuring it out ahead of time. Remember that the software is free to download.
Posted by bergv at 9:45 AM
Information for Quiz 1
I make up quizzes and tests by going through the notes and listing the most important topics. Questions (which tend to be simpler on quizzes) might ask for reasonable values, why a value is impossible, the answer to problems like those in homework, explanations of why some thing happened, a statement of how something would be different if (fill in an idea here), examples of principles in action, evidence of something, explanation or interpretation of results, examples of something, similarities and differences between two things... just about anything except definitions. No lab material on quizzes.
Thanks to the people who discover broken links in the website. A lot of things have to be working correctly for the website to function optimally, and I can use the help for my old brain.
Topics on the first quiz include:
WP: what it means, what causes it to be a particular value, and how it is (and when it isn't) involved in water movement.
SP, PP, MP: pretty much the same as WP above.
Examples of values (possible, impossible)
Simple arithmetic involving negative numbers (write out the addition so you won't get it wrong)
The four things that move water
Relationship between osmotic (=solute) potential and osmotic pressure
The two ways water moves
Properties of gases, liquids and solids
Units and scales for expressing water potential
Water under tension: evidence for this in plants, where you see it, where you don't
Reasonable values for WP, SP, PP
Properties of walls & membranes
Basic water potential equation (and how to use it)
Problems like the easy set
That seems like enough
Posted by bergv at 9:05 AM
January 20, 2010
Feedback for first lab handin
Here is information and feedback for handins, and for many other things.
PART TWO
1. The pellet (bottom) after the first spin contains sand (white), chunks of tissue (green) and whole cells, plus maybe some other cell bits.
The supernatant ("nat-" means swim, so it's the stuff swimming at the top) contains water (mostly), solutes, and many organelles from the broken open cells. It is light green because it contains both chloroplasts and chlorophyll.
After the second spin, the pellet is mostly chloroplasts (which we could see with an ordinary light microscope). In a later lab we will isolate chloroplasts and put them in test tubes to perform for us. They will stay alive for about an hour.
The supernatant contains the less dense organelles, such as mitochondria (which we need a faster centrifuge to pellet), the water and solutes, and chlorophyll from broken open chloroplasts.
PART THREE
1. There is always a large range of minimum concentrations of salt and sugar (particularly sugar) that people can taste. Interestingly, East Asian students can almost always taste weaker solutions than Americans, and even American students have slow shifted over time, so that it takes more sugar for them to taste.
2. 0.01 M HCl is 10^-2 M (0.01 = 10^-2) HCl. the ^ means exponent, "to the". This -2 tells us the pH is 2.
3. The MW or NaCl is 58 (23 + 35). To make a liter of 1 M solution, you would use 58 g. To make 100 mL of a 1M solution: 100/100 x 58, or 5.8, To make a half liter of that solution, 500/1000 x 5.8 = 2.9 g of NaCl.
You can do this in one step, but if you can do that, you don't need my help. This one step at a time explanation helps the more chemically challenged.
4. At 58 g of NaCl for 2 degrees and 3000 m giving a 20 degree drop in boiling point, you are going to need 10 x 58 (=580) g of NaCl to bring the boiling point up to that of sea level.
People used to tell me that "the spaghetti would tast bad" until I put in the fact that one of those cylinders (quaint) of salt contains about 26 oz. Those in the know (or who look it up) realize that a pound (32 oz) is 454 g of salt. So you would need over a pound of salt in just a liter of water, and this wouldn't even dissolve! So it's not even possible to bring the boiling point up to that of sea level using salt.
This question was inspired by a trip on 14,000 Mt. Rainier in Washington, where a chemist friend of mine and I heard some engineers saying you needed to add some extra salt (say, a couple of teaspoons) to compensate for the altitude. The chemist and I looked at each other and silently shook our heads.
Posted by bergv at 8:10 AM