Author: Lindsey Delve

Carmel College

Mitosis and cell cycle maths hw
Name __________________  MEG_________   Tutor________________________
Q1.A student investigated mitosis in the tissue from an onion root tip.
 A student counted the number of cells she observed in each stage of mitosis.
Of the 200 cells she counted, only six were in anaphase.
One cell cycle of onion root tissue takes 16 hours. Calculate how many minutes these cells spend in anaphase.
Show your working.
 
Answer = ................................... minutes
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Q2.
     The graph shows information about the movement of chromatids in a cell that has just started metaphase of mitosis.

(i)      What was the duration of metaphase in this cell?
   minutes
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(ii)     Use line X to calculate the duration of anaphase in this cell.
   minutes
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(iii)    Complete line Y on the graph.
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(c)     A doctor investigated the number of cells in different stages of the cell cycle in two tissue samples, C and D. One tissue sample was taken from a cancerous tumour. The other was taken from non-cancerous tissue. The table shows his results.
 
| | Percentage of cells in each stage of the cell cycle
| Stage of the cell cycle | Tissue sample C | Tissue sample D
| Interphase | 82 | 45
| Prophase | 4 | 16
| Metaphase | 5 | 18
| Anaphase | 5 | 12
| Telophase | 4 | 9

(i)      In tissue sample C, one cell cycle took 24 hours. Use the data in the table to calculate the time in which these cells were in interphase during one cell cycle. Show your working.

 
Time cells in interphase ...................................... hours 
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Q3.          The table shows some differences between three varieties of banana plant.
 
| | Variety A | Variety B | Variety C
| Number of chromosomes in a leaf cell | 22 | 33 | 44
| Growth rate of fruit / cm^3 week^–1 | 2.9 | 6.9 | 7.2
| Breaking strength of leaf / arbitrary units | 10.8 | 9.4 | 7.8

(a)     (i)      How many chromosomes are there in a male gamete from variety C?
 
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(ii)     Variety B cannot produce fertile gametes. Use information in the table to explain why.
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          In some countries very strong winds may occur. Banana growers in these countries choose to grow variety B.
(b)     (i)      Use the data in the table to explain why banana growers in these countries choose to grow variety B rather than variety A.
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(ii)     Use the data in the table to explain why banana growers in these countries choose to grow variety B rather than variety C.
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(c)     Banana growers can only grow new variety B plants from suckers. Suckers grow from cells at the base of the stem of the parent plant.
Use your knowledge of cell division to explain how growing variety B on a large scale will affect the genetic diversity of bananas.
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Q4.   A sample of epithelial tissue from the small intestine of an animal was analysed.
Some of the cells had 8.4 units of DNA, others had only 4.2 units.
(i)      Use your knowledge of the cell cycle to explain why some cells had 8.4 units of DNA and others had only 4.2 units.
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(ii)     How many units of DNA would you expect to be present in a gamete formed in this animal as a result of meiosis?
 
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Q5.          The diagram shows a cell cycle.
 
The time required for a cell to complete the cell cycle was 4 hours 18 minutes.
Calculate the time required in minutes for this cell to multiply to produce eight cells.
Show your working.

 
 
 Answer .....................................................
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Q6.Metastatic melanoma (MM) is a type of skin cancer. It is caused by a faulty receptor protein in cell-surface membranes. There have been no very effective treatments for this cancer.
Dacarbazine is a drug that has been used to treat MM because it appears to increase survival time for some people with MM.
Doctors investigated the use of a new drug, called ipilimumab, to treat MM. They compared the median survival time (ST) for two groups of patients treated for MM:
•        a control group of patients who had been treated with dacarbazine
•        a group of patients who had been treated with dacarbazine and ipilimumab.
The ST is how long a patient lives after diagnosis.
The doctors also recorded the percentage of patients showing a significant reduction in tumours with each treatment.
The total number of patients in the investigation was 502.
The table below shows the doctors’ results.
 
| Treatment | Median survival time (ST) / months | Percentage of patients showing significant reduction in tumours
| Dacarbazine | 9.1 | 10.3
| Dacarbazine and ipilimumab | 11.2 | 15.2

(a)     The doctors compared median survival times for patients in each group.
How would you find the median survival time for a group of patients?
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(b)     In many trials of new drugs, a control group of patients is given a placebo that does not contain any drug.
The control group in this investigation had been treated with dacarbazine.
Suggest why they had not been given a placebo.
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(c)     A journalist who read this investigation concluded that ipilimumab improved the treatment of MM.
Do the data in the table support this conclusion? Give reasons for your answer.
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