Agriculturalists investigating a poorly growing onion crop discovered it was infected with a fungal pathogen. The fungus secreted a lectin-like protein in the soil surrounding the onions’ roots. Lectins often accelerate mitosis in root systems, but this abnormal growth creates weaker plant tissues. Fifty cell samples were observed for the struggling onion crop. The observed number of cells in each part of the cell cycle are shown below: Interphase Mitosis

Sample One 21 29

Sample Two 18 32

Sample Three 25 25

a) State the null and alternative hypothesis related to the data.

b) Calculate the chi-square values for interphase and mitosis using the samples as the observed values (o) and trial 1 in table 3 as your expected data (e).

c) Using the chi-square table, determine the critical value for interphase and mitosis of the struggling onion crop using the chi-square values in (b).

p-

value Degrees of Freedom

1 2 3 4 5 6 7 8

0.05 3.84 5.99 7.82 9.49 11.07 12.59 14.07 15.11

0.01 6.64 9.21 11.34 13.28 15.09 16.81 18.48 20.09

d) Based on the chi-square and critical value, draw a conclusion about the null hypothesis.

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interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle

d. planting trees

the trees take in carbon to make oxygen.