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chie chie
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Posts: 35
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12 years ago
Dihybrid Corn Lab: (1 of 9)
The individual kernels of corn are a stage in the life cycle of a corn plant. Each kernel develops from a separate fertilization of an egg to form a zygote, a seed. The kernels in the above diagram represent individuals of an F2 generation. They have been produced from a parent cross that was pure-breed

  Numerical Response

A pea plant homozygous in both yellow seed colour and smooth coat is pollinated with a purple and wrinkled pea plant.
Write out the letters that would represent the cross for the P1 =  ______  x  ______
 Answer:  P1 =  YYSS  x  yyss
 
 Question 33 (4 points)
Complete a Punnett square of the parental cross. Record genotype(s) and phenotype(s). Record the genotype and phenotype ratio.  4 marks
 16 heterogenous Yellow smooth maize; Ratio yellow smooth, yellow wringkled, purple smooth; purple wringkled is 16:0:0:0

  YS YS YS YS
ys YySs YySs YySs YySs
ys YySs YySs YySs YySs
ys YySs YySs YySs YySs
ys YySs YySs YySs YySs
 
 

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Question 34 (8 points)
The genotype YySs represents the offspring or the F1 generation. Complete a Punnett square for a F1 cross. Record genotypes and phenotypes. Record the phenotype ratio.
8 marks
 empty YS  Ys  yS  ys 
 YS YYSS   YYSs  YySS  YySs
 Ys  YYSs  YYss  YySs  Yyss
 yS  YySS  YySs  yySS  yySs
 ys  YySs  Yyss  yySs  yyss

Use this table to build your punnett square.yellow smooth: yello wringkled: purple smooth: purple wringkled 9:3:3:1
 
 

View hint for Question 34
 
 (sr) Genetics 3; you should have 9 different genotype categories and 4 different phenotype categories.
How did you complete this question? This is basic in dihybrid questions and one in which you will have to do many times. If you have stumbled, phone, contact by e-mail, review the (sr), do something about it right away.
 

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Question 35 (1 point)
Numerical Response

Calculate the expected probability of the four possible phenotypes. For example the probability of getting a yellow and smooth seed is 9 divided by 16, or 9/16.

Probability :  ______     ______      _______    ________ 
                      yellow     yellow       purple       purple                                             
                     smooth   wrinkled     smooth    wrinkled

(Record your answer as a decimal number to two significant digits)
0.56, 0.19, 0.19, 0.06
 In recording probability (or just a number) a 0 is always placed before the decimal. A probaility of 75/100 = 0.75.

0.341; leading zeros are not significant; rounded to two significant digits ? 0.34
0.0738; in two significant digits ? 0.074
See page 749 in textbook for more information.
 

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Question 36 (1 point)

Numerical Response

The information above represents an F2 generation. Identify the number of corn kernels that represent the four phenotypes.

Number :    ______    _______      _______     ________ 
                   yellow     yellow       purple        purple                                             
                  smooth   wrinkled     smooth     wrinkled
9,3,3,1

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Question 37 (2 points)
Use the information from the last question.

Numerical Response

Calculate the observed probability of the four possible phenotypes. This is calculated as the total number in a phenotype category divided by the total number of corn kernels in the sample.  2 marks

Probability :  ______     ______       _______    ________ 
                      yellow     yellow       purple       purple                                         
                     smooth   wrinkled     smooth    wrinkled

(Record your answer as a decimal number to two significant digits)
0.56, 0.19, 0.19, 0.06

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Question 38 (2 points)

Also, use the information from the last two questions.

Numerical Response

Corn cobs representing an F2 generation were distributed randomly to groups in a Biology 30 class. Their group results appear in the above chart. Combine your phenotype result with that of other groups. Calculate the totals for each phenotype and the total number of kernels (seeds) of all the corn cobs. 2 marks

Total numbers:   ______     ______      _______    _________  _______
                            yellow     yellow       purple       purple       Total                                         
                           smooth   wrinkled     smooth    wrinkled
601,201,201,67 Total = 1071

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Question 39 (2 points)

Also, use the information from the last three questions.

Numerical Response

Using the data from the combined results of the class, calculate the observed percentage for each phenotype. (Use: phenotype number divided by the total multipled by 100% = __ %.) 2 marks

Percentage :    _______    _______    _______    ________ 
                        yellow     yellow       purple       purple                                             
                        smooth   wrinkled    smooth    wrinkled

(Record your answer as a whole number percentage.)
56%, 19%, 19%, 6.3%

Question 40. In Labs or Written Response questions:

•Interpret is to give meaning to the data that adds to the original data.
What might your corn cob mean with respect to the expected results. Note that when you combine all the data collected as a class, observed probabilities are very close to expected probabilities. This is related to sample size which is a point that is made during population studies in ecology

•Evaluate is to give the worth of something (the lab) by identifying the good or bad points (say on how the lab was conducted, experimenter error, etc.).
Answer the following two questions.

(a) How does the corn cob that you analyzed compare with the expected results of a  9:3:3:1 ratio of dihybrid cross with both parents heterozygous in both traits? 2 marks

(b) Interpret your observed experimental results with the expected results of a dihybrid cross.  2 marks
My concern is question 40,  38 to 40 2nd pic but the 1st pic has something to do with question 40.
Source  McGraw Hill Ryerson
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12 years ago
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