Required Practical 7 Flashcards
(41 cards)
What statistical test should the student use in RP7?
Student T test.
What does the T-test compare in this experiment?
The difference between two means.
What is a suitable null hypothesis for this experiment?
There is no difference in the distance moved by the pigments / any difference is due to chance.
What does a 4% probability in the test suggest?
The probability that the difference is due to chance is 4% / 0.04.
What should be done with the null hypothesis if p = 0.04?
Reject the null hypothesis.
What does the data show about green leaf pigments?
They move significantly further from the origin than yellow leaf pigments.
Why use pencil, not ink, for the origin line in chromatography?
Ink and pigments would mix / pencil line stays in place.
Why can’t you see the solvent in chromatography?
Because the solvent is colorless / cannot be seen.
Why do pigments have different Rf values?
Solvent/pigments move different distances.
How is Rf value calculated?
Distance moved by spot ÷ distance moved by solvent front.
Why are Rf values useful?
They are constant for the same pigment and can be compared.
Why wash the chromatography paper after the experiment?
To prevent pigments/solvent from running off the side.
Why calculate the mean distance moved by a pigment?
It standardises readings.
What does calculating the mean allow?
It allows comparisons to be made.
Why is the mean used for pigment movement?
Because pigment may spread or move different distances.
What does the mean distance represent?
It is the average distance moved by the pigment.
How can a thick cuticle affect pigment extraction?
It prevents pigments from being transferred to the paper.
Why do thicker leaves reduce pigment concentration?
More cells/tissue without pigment or lower amount of pigment.
Why do spines show little pigment?
Because spines have little or no pigment.
How to check for chlorophyll presence later?
Repeat chromatography at different times.
What would you check for in repeated chromatography to confirm chlorophyll?
Look for green substance at same Rf.
Why do yellow leaves grow less?
They have less or no chlorophyll.
What is the effect of less chlorophyll on photosynthesis?
Less photosynthesis occurs.
Why does less photosynthesis reduce growth?
Photosynthesis products are needed for growth/synthesis.
