deionized water and gibberellic acid.
deionized water and gibberellic acid.
INTRODUCTION
seedlings. This experiment forms the basis of your major assignment due later in semester. The peas in the experiment have a genetic mutation that means they produce little or no GA3, a hormone that influences lengthening of the stem during growth. The experiment will test whether adding GA3 in a solution overcomes the effect of this mutation. You will harvest the experiment in Lab 4, when your demonstrators will discuss how to go about writing the report.
length of one individual of one species and relate their structure to their functions.
METHODS
1. Experiment set-up: The effect of the hormone gibberellic acid on growth of dwarf peas.
The class will work together to set up this experiment.
Collect 20 dwarf pea seedlings. Number them 1 to 20 and label them as such.
Divide them into two groups of 10. Pots 1-10 will be treated with a solution containing deionized water and gibberellic acid. Pots 11-20 will be a control, and will be given only deionized water. (i.e. no GA3).
Measure the height of every seedling from the base to the stem apex (tip). Your demonstrator will help you find these points and to not mistake the tip of a tendril for the stem apex. Record the plant heights in millimetres in Table 4.1.
Place the pots in the sink for the next step. Measure out and pour 100 mL of deionised water into the sand in the pot of each control plant. Set the control seedlings aside.
Pour 100 mL of the GA3 solution (which contains only GA3 and DI water) onto the sand in the pot of each treatment seedling.
The plants will receive these treatments plus basic other nutrients twice weekly until you measure them again in two weeks’ time.
.
1
INTRODUCTION
This week you will complete the experiment you set up in Prac 3. Recall that dwarf peas have a genetic mutation that predisposes them to remain much shorter than normal peas. The mutation reduces the production of a hormone called gibberellic acid (GA3), which normally induces the stem to lengthen. A lack of gibberellin means the stems remain short in comparison to normal pea plants of the same age.
This experiment explores whether it is possible to overcome the genetic mutation by providing the dwarf plants with GA3 from an external source.
METHODS
1. Gather together the plants used in the experiment, and separate them into their two treatments.
2. Start with the plants that received the GA3 treatment. Measure their final heights in the same way that you measured in week 3. Enter the final heights in the relevant column of Table 4.1. Make sure that you match the final heights of each plant to the correct measurement of initial height i.e. in the same individual.
3. Repeat the procedure for the plants in the control treatment, but enter their heights in the appropriate columns in Table 4.2.
4. Using the Tables 4.1 and 4.2, calculate the change in height of each plant over the two weeks’ growth. It is these changes in height that are the data of interest in this experiment!
5. Calculate the mean and variance for each of the two treatments following the instructions below and using Tables 4.1 and 4.2.
Table 4.1 Calculations for GA3 treated dwarf pea plants
A B C D E Plant Final height (mm) Initial height (mm) Change in height (mm) ( x 1 , subtract C from B) x 1 2 D*D 1 360 83 2 400 110 3 140 73 4 130 60 5 310 82 6 170 68 7 200 74 8 180 67 9 320 87 10 235 90 ? ? n 1 ? ? ( ? ! ) ! ? ! ! ? ! = ? ∑ ? − ! ( ∑ ?) ! ? − 1 s 1 2 =
Table 4.2 Calculations for untreated (control) dwarf pea plants
F G H I J Plant Final height (mm) Initial height (mm) Change in height (mm) ( x 2 , subtract H from G) x 2 2 I*I 11 160 67 12 155 65 13 130 68 14 200 80 15 205 83 16 160 48 17 130 78 18 135 59 19 114 76 20 179 72 ? ? n 2 ? ? ( ? ! ) ! ? ! ! ? ! = ? ∑ ? − ! ( ∑ ?) ! ? − 1 s 2 2
Make sure you complete the tables and the calculations in the lab manual. The calculations will be marked before you leave, and contribute to your assignment mark!
A. Calculate the mean (?) and variance ?? for the GA treatedplants.
i. Add up all of the numbers in column D. Enter the total in the unshaded cell labeled ∑x1. This symbol means ‘sum of x for treatment 1’, where x denotes the variable of interest. Throughout the calculations any numbers that you work out for the GA+ plants will have the subscript 1.
ii. Count the number of plants you have in your sample. This is n1, the sample size for this treatment. It will be 10 unless one or more of your plants died. Enter this number in Table 4.1.
iii. Divide ∑x1 by n1, to work out the mean (?) for this sample, and enter it into the table.
iv. Square the ‘sum of x,’ i.e. multiply ∑x1 by ∑x1. This is denoted as (∑x1)2. Write the value of (∑x1) in Table 4.1.
· Keep an eye on where those brackets are – they mean you add up all the x’s before squaring! This matters later on.
v. Now, square each value in column D and write the product in column E.
vi. Add up all of the numbers in column E and enter the value in the blank cell at the bottom of the column. This total is called the sum of the squared values of x (or sum of squares) and is designated as ∑x 2 in the formula for variance.
tice Nthoe lack of brackets in the name of this value! It means this number is not the same as the one you calculated in step iv.
· The number ∑x2 should be much smaller than (∑x1)2, which you calculated at step iv. Check that the number at the bottom of column E is less than the last number in column D.
vii. Calculate the variance s1 for the treated plants using the formula provided below.
· Make sure you insert the numbers from Table 4.1 in their correct positions in the formula.
· There is space for your calculation next to Table 4.1
Note: s2 is the symbol for variance i.e. it is the number you want. Do not square the result!
B. Calculate the mean (?) and variance ? for the controlplants.
Repeat the steps above using the changes in height for the control plants and Table 4.2. Numbers that relate to this group of plants have the subscript 2, so that you can identify them.
28
C. Calculate the value of t for this experiment
29
!Enter the values for n1, n2, ? , ??, ?!
and ?!?
in Table 4.5 in the Results section.
Use these values to calculate the value of t for the comparison, using the formula
? ! ! + ? ! ! ? ! ? !? =
?! − ?!
Note: If you follow these instructions carefully, you should not get a negative value for t. If you do, check your calculation thoroughly to make sure that you have all the values in their correct positions.
Derive the degrees of freedom for this dataset
df = (n1 -1) + (n2 – 1) =
Consult the tables of critical values of t that are available in class to find the critical value of t for this number of df and p = 0.05
Read down the ‘Degrees of Freedom’ until you reach the number you calculated above. Then read across this row to the column titled ‘p=0.05’. The number in this cell of the table is called the ‘critical value of t’ or tcrit Write it below.
tcrit =
Decide whether the value of t you calculated is significant:
First, work out if your calculated value of t is greater than, equal to, or less thanthe critical value and complete the following statement:
My calculated t value is the critical value of t.
If your value is greater than the critical value, your t-value is considered significant. This implies that there is a real difference between the means at probability level (p) of 0.05., and that the GA3 had an effect on plant growth.
If your calculated value is less than the critical value, your t-value is considered not significant. This implies that there is no real difference between the means at probability level (p) of 0.05., and that the GA3 did not have an effect on plant growth.
RESULTS
Table 4.3 Summary statistics for GA treated and untreated control dwarf peas.
Treatment
Sample size
Mean change in height
Variance
GA treated plants
n1 =
?? =
S 2 =
1
Control plants
n2 =
?? =
S 2 =
2
Value of t =
My calculated t value is the critical value of t at p=0.05 and df =
Write a statement about the effect of GA3 on the growth of the peas in your experiment:
DISCUSSION
Your demonstrator will hold a class discussion on the results of the experiment, and how to write up your report. The discussion will consider the following, which should all be included in the discussion section of the report:
a conclusion about the effect of the hormone on the growth of the peas in your experiment.
an assessment of whether the results you saw are consistent with the prediction.
a discussion of what GA3 does in the plant e.g. the effect it is known to have on growth, and how it works, where it act
an assessment of whether or not your results are consistent with this knowledge. If not, then what may have affected the results that you do have?
30
WRITING YOUR REPORT
What to submit
Your report
A completed ECU assignment cover sheet
Your report is the major assignment for this unit. It must be submitted using the link on the unit website.
No email submissions will be accepted.
Format and Presentation
Your report is to be submitted in the format described below, as the marks are allocated according to section. Write in clear and concise formal or semi-formal English – note that this is not the style in which your lab manual iswritten.
Your report should
be typewritten. The work must be submitted online, and has to be saved as docx, rtf or pdf format.
be double-spaced, to allow staff to add comments.
in a minimum font size of 11.
have margins of 3.0 cm on all sides.
have numbered pages.
An assignment template for use with MS Word is available in the assignment folder on the unit website. It includes the ECU coversheet for use with Turn-it-in. Start typing your assignment on the third page of the document.
Structure
Divide your report into the following sections, and present them in the order listed.
"You need a similar assignment done from scratch? Our qualified writers will help you with a guaranteed AI-free & plagiarism-free A+ quality paper, Confidentiality, Timely delivery & Livechat/phone Support.
Discount Code: CIPD30
WHATSAPP CHAT: +1 (781) 253-4162
Click ORDER NOW..
