R2 value
statistical measure of how close the data are to the fitted regression line, also known as the coefficient of determination
what did we use r2 for?
used to determine how 'good' your model is (in case of jump lab how well your linear regression fit your actual data), and whether you can likely use this model to predict future values
what does an r2 value close to 0 represent?
IT means that the model is crap! i.e. the real data points do not lie upon the fitted linear model
what does an r2 value close to 1 represent?
It means the model is perfect�i.e. all data points perfectly lie on the regression line. And the regression model will likely be accurate in predicting future values
what does it mean when two variables are directly correlated (inversely correlated)?
That as x goes up in value so does y. That as x goes up, y goes down.
Would it have been possible to measure an R2 value on data involving mean jumping ability of women vs men?
NO! This only applies where you have data that generates a scatter plot with x and y values�not categorized data of this sort (boy vs girl). Here you would have to use different statistical measures to evaluated significance of data.
hypothesis involving jump height and calf circumference
People with larger calves will be able to jump higher.
Why might an outlier occur in a data set? Why might you want to remove outliers from a data set?
Experimental error. It makes it difficult to interpret significance of the data, because this one point can have such influence over the data set, especially when trying to model the data with, say a linear regression line.
what is diffusion?
net movement of molecules or atoms from a region of high concentration to a region of low concentration
simple diffusion? active transport? facilitated diffusion?
simple diffusion: the unassisted passage of small, hydrophobic, nonpolar molecules from higher concentration to a lower concentration
active transport: the movement of molecules across a cell membrane from a region of their lower concentration to a region
Why would a starch/water solution be expected to have a low filtration rate? How does viscosity influence filtration rates?
Starch is used as a 'thickening agent' --> causes a highly viscous material when mixed with water. High viscosity (think molasses) = low filtration rate.
How is molecular weight expected to influence rates of diffusion? Which diffused faster in agar, potassium permanganate or methylene blue? Why?
The higher the molecular weight the slower the rate of diffusion. Therefore potassium permanganate is expected to diffuse faster because it has a lower mol. weight than methylene blue.
How is the surrounding medium expected to affect rates of diffusion of a molecule?
The more fluid the surrounding medium the faster solutes can diffuse throughout the medium. The more stationary the medium (think agar with its lattice structure) the slower the solute will diffuse.
What is osmosis? What is facilitated diffusion?
It is the movement of a solvent across a semipermeable membrane from solution with low osmolarity to solution with high osmolarity. It is usually described in terms of water as solvent, and is a much more efficient process if the solutes in question canno
In what part of the lab did we investigate active transport?
we didn't, we only investigated passive processesq
What is dialysis tubing? On what chemical/physical basis does it prevent movement of molecules? What is meant by semipermeable membrane?
IT is a semipermeable membrane, man-made�generally made of cellulose. It is a size restriction based method of restricting movement of molecules�i.e. it has small pores. Semipermiable means that some molecules are permeable across the membrane while other
If rates of diffusion across dialysis tubing depend on size of molecules alone, rank the following solutes from having the slowest to fastest rates of diffusion: NaCl, glucose, fructose and sucrose, albumin?
NaCl<glucose = fructose < sucrose
Understand that osmolarity (or osmotic pressure) is a 'colligative property' meaning it depends only on the number of solute particle in solution (not their chemical properties). For this reason, when an individual molecule of NaCl dissolves into its cons
1M NaCl
How do you expect the following factors to influence instantaneous rates of diffusion of a permeable solute across dialysis tubing: (a) What if the pores in membrane were larger? (b) there were a larger number of pores? (c) The solute was highly concentra
All (larger, greater number of pores, more concentrated solute) would be expected to increase instantaneous rates of diffusion. More open Na channels = faster rates of diffusion of Na into the cell. The more concentrated Na is on outside of the cell the f
How does dialysis tubing differ from a true cell membrane? What does the phospholipid bilayer refer to? On the basis of what physical/chemical properties does it prevent movement of molecules? E.g. why is a true cell membrane (at 'rest') impermeable to Na
Dialysis tubing restricts based on the size of molecules. The cell membrane is more complex made up of a phospholipid bilayer with inner lipid chains that cause the membrane to be impermeable to small charged molecules such as ions. That is why Na+ can pa
Be able to provide anticipated results from mock experiments involving placing a hypothetical cell in different solutions...e.g .what happens to a cell placed in hypertonic, vs isotonic vs. hypotonic environments in case where only water can transfer the
In hypotonic it swell and may eventually burst; in hypertonic it shrink; in isotonic it is happy and not net movement of water.
Know that when you measure change in weight in your dialysis sac (or any change in weight for that matter) you should calculate final weight-initial weight such that a weight gain will be equal to a positive number; and a weight loss will be indicated by
final weight-initial weight
15) When a dialysis sack containing NaCl solution is placed in pure water, if the sac is permeable to sodium and chloride ions, what is expected to happen once the system reaches equilibrium? Do you expect the sac to show weight gain or loss? What test mi
At equilibrium the sac would be expected to lose weight, with loss of Na and Cl from sac into beaker solution. And Na+ Cl- concentrations will be equal inside sac and surrounding solution. You could perform a silver nitrate test on the 'beaker solution' a
16) When a dialysis sack containing glucose solution is placed in pure water, if the sac is permeable to glucose what is expected to happen once equilibrium has been achieved? Do you expect the sac to display weight gain or loss? What test might you prefo
Sac loses weight due to loss of glucose�concentration of glucose inside sac will be equal to concentration in beaker solution once equilibrium is achieved. A Benedict's test can be performed to test for presence of reducing sugars, such as glucose. You mu
If the sac had instead been permeable to sucrose, could you have used this same test for sucrose dilalyzate? Why not? What is a reducing sugar vs. non-reducing sugar? What does the term 'reducing refer to?
No it could not have been used because sucrose cannot form this linear structure and therefore cannot reduce the copper. (Though there is some potential for sucrose to give a positive result if it is first hydrolyzed to its component glucose and fructose
When a dialysis sack containing albumin, a relatively large molecule, to which the membrane is impermeable, is placed in pure water a weight gain is measured? What is the reason for the measured weight gain?
Osmosis or transfer of water from beaker into the sac causes weight gain.
Design a dialysis experiment to concentrate the solution of albumin, assuming the dialysis tubing is also impermeable to sucrose? What might be a test to determine whether your albumin was indeed concentrated? i.e. what can you do to test for presence of
Put the albumin solution sac in a high concentration sucrose solution�this will cause water to move from the sac to beaker causing the albumin to become more concentrated. A biuret test for peptide bonds (peptide bond complexes with copper ions in copper
What were the three tests we carried out in this lab to measure for presence of A) amylose? B) Reducing sugars? C) Proteins? Be able to describe how the test is conducted and what a positive result looks like? And very basic chemistry behind each test?
A)A starch iodine test�here a positive test indicates amylose due the alignment of iodine along the linear amylose polymer;B) Benedicts test; C) Biuret test
You isolate pea starch from some peas and potato starch from some potatoes. When you add iodine to the two starches the pea starch turns bright purple and the potato starch remains orange/yellow what can you conclude about the relative ratio of amylose/ a
Pea has a higher amylose/ amylopectin relative to the potato.
3) You want to figure out if onions have a high ratio of amylose/amylopectin. Because you remember that pea starch gave such a nice positive purple result you use it as a comparison during your test. Again you find that pea starch gives nice purple signal
This means no amylose�this could be because a starch did not have a lot of amylose and more amylopectin�or because it did not contain any starch!�i.e. you cannot conclude from a negative test that the substance must contain amylopectin.
you carry out a Benedict's test: you test some apple juice and get mild positive result in green/yellow range, you conclude that apples contain some reducing sugars. You then test some dissolved table sugar (sucrose) and get a negative result. You conclud
Hint: no it is not! Water and Albumin are not a sugars! Water is H20 and albumin is a protein. Same as with the iodine test�a negative result just means no reducing sugar�it could be that this is due to fact that substance is a non-reducing sugar�or due t
What is a negative control? If water had given you a positive result in any of the tests covered in this lab what might this have told you about your experimental conditions and how might this have made you question any other positive results you obtained
A negative control is an experimental test you run that you know a priori should give a negative result. If you got a positive result with your neg. control (water) then this would potentially reveal that there is something wrong with your experiment (pos
What is a positive control? If substances such as glucose, and the amylose and the albumin, which you know should give positive results on the Benedict's, iodine test and Biuret test respectively, gave negative results, what might this tell you about your
A positive control is an experimental test you run that you know a priori should give a positive result. If you got a neg. result with your positive control (glucose etc.) then this would potentially reveal that there is something wrong with your experime
Even though proteins are made up of linked amino acids and amylose is made up of linked glucose molecules_ would a solution of free amino acids and glucose molecules be expected to give positive results on the biuret test and the starch-iodine test respec
No, because these tests, test for presence of polymerized versions of these molecules (amylose in the case of starch iodine; peptide bond/protein in case of biuret's).
What is a peptide bond?
It is the chemical bond formed when the carboxyl group of one amino acid reacts with the amino group of another amino acid. It is the bond that links amino acids into proteins.
Which layer is responsible for photon detection Photoreceptor layer. What is the name of light sensing cells in this layer?
Rods and Cones
What is the specialization of each of these cell types in terms of light intensity and wavelength of light to which these cells respond?
Rods highly light sensitive�used for detection in low light�no distinction between colors (wavelength of visible light). Cones minimal light sensitivity�so used for bright light detection�three different types of cones (red blue green) are specialized in
hich layer contains neurons that transmit signal via the optic nerve?
Retinal ganglion cell layer
Be able to explain why we have a blind spot. Be able to name that area of the retina where the blind spot occurs
Optic disk�lack of photoreceptors in region of optic nerve convergence and exits the retina.
What is the cochlea?
It is the spiral fluid filled inner ear organ where sound waves are detected for audition.
What is the organ of corti?
It is the actual receptor organ in the cochlea. It also follows a spiral shape. It is the apparatus/tissue where the auditory signals are first converted to nerve impulses.
What did Snellen eye test, test for?
Visual acuity
Have a practical sense of what is meant by 20/20 vision or 20/15 vision
person was standing at 20 feet and could identify letters on the eye chart that a normal person could only identify at 15 feet" this person more acute vision than normal. Also be able to define the term myopia. Nearsighted�subpar visual acuity at distanc
How did we test for astigmatism?
Looking at chart where lines radiate across a half circle�focus in at center and look for certain lines look dim.
How did we test for depth perception?
Closing a single eye and putting pencil into a test tube.
What did the Ishihara plates test for?
color blindness
What about the Weber test? (What is the difference between conductive and sensorineural hearing loss�how do you test for conductive hearing loss?)
Weber test tested for conductive hearing loss�placed tuning fork on top of head and tested to see if the individual sensed the vibrations louder in either ear. If the vibrations are sensed as louder in an ear this indicates conductive hearing loss in this
What was the Romberg test? What was it testing for?
Where you drew lines on board and looked at the ability of the individual to remain erect (not sway) while closing their eyes. The ability to maintain vertical balance relies on vision, proprioception and vestibular function. Only two of these systems nee