Use the following information to answer the next four questions.
Tomato Plant Leaves
In tomatoes, regular leaves (L) are multilobed and serrated and potato leaves (l) are broad, smooth, and single (Image 1). Red fruit (F) is dominant to yellow fruit (f). Pictured below, potato leaves (left) and regular leaves (right).
A cross is carried out between two pure lines of tomato plants, one having regular leaves and red fruit and the other having potato leaves and yellow fruit. The F1 generation all have regular leaves and red fruit. The F1 individuals are then crossed with one another.
1) The expected phenotypic ratio for leaf shape and fruit colour genes is 9:3:3:1, if both genes are on different chromosomes and assort independently during gamete formation. The information below represents two sets of data collected from the above cross. Data Set 1 is from a population of 5000 tomato plants and Data Set 2 is from a population of 50 tomato plants.
Phenotypes
Observed Probabilities
Data Set 1
(N = 5000) Data Set 2
(N = 50)
Regular Red
0.58 0.050
Regular Yellow
0.16 0.29
Potato Red
0.20 0.050
Potato Yellow
0.060 0.61
A. Compare both data sets to the expected probabilities. Are there any significant differences between the observed results and the expected results? Explain. (2 marks)
B. Using the most reliable data set, are the genes for leaf shape and fruit colour assorting independently? Explain. (1 mark)
2) In tomato plants, the genes for fruit colour (C), fruit fructose content (F), fruit length (L), and plant height (H) are all found on chromosome 4. Map distances between the four genes are shown below.
Genes Distance in Map Units
H and F 40
F and L 12
C and F 75
L and C 87
L and H 52
Sketch and label a gene map to identify the order of the four genes on chromosome 1 in tomato plants.
3)
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