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Synthesis

(c) Cancerous cells are often characterized by a large

nucleus. Based on what you know about cancer and

cell division, provide an explanation for the enlarged

nucleus.

(d) Why are malignant (cancerous) tumors a greater

threat to life than benign tumors?

(e) Provide a hypothesis that explains why the skin is so

susceptible to cancer.

(f ) A scientist finds a group of irregularly shaped cells

in an organism. The cells demonstrate little

differentiation, but the nuclei in some of the cells

stain darker than others.

(i) Based on these findings, would it be logical to

conclude that the organism has cancer? Justify

your answer.

(ii) What additional tests might be required to prove

or disprove the hypothesis that the cells are

cancerous?

INVESTIGATION 17.2continued

Comparing Mitosis and Meiosis

In this investigation, you will model and compare the events of

mitosis and meiosis. In this model, you will create homologous

chromosomes that have the same size and shape, but different

colours. This will show that they are similar but not identical.

Materials

red modelling clay plastic knife

blue modelling clay sheets of paper

green modelling clay pencil

Procedure

For each step, make a coloured sketch of your model with

appropriate labels. Include brief descriptions of your steps

and make sure to use the same step numbers as given.

Part 1: Mitosis

1. Take some red clay and roll it between your hands to
   create a piece 10 cm long and about as thick as your
   finger. Make another piece about 5 cm long.


2. Repeat step 1 with the blue clay.


3. Make an identical copy of each piece of clay. Then
   attach the identical pieces with a green ball of clay
   (Figure 1).


4. Draw a line down the length of a sheet of paper.
   Line up the four chromosomes along the line
   (Figure 2).

Purpose Design Analysis

Problem Materials Evaluation

Hypothesis Procedure Synthesis

Prediction Evidence

INVESTIGATION 17.3 Report Checklist

590 Chapter 17 NEL

Figure 1

Figure 2

5. Remove the green balls and move each
   of the single pieces of clay to opposite
   ends of the paper (Figure 3, next page).


6. Before every mitotic division, each
   chromosome is duplicated during
   interphase. Make an identical copy
   of each piece of clay as before
   (Figure 4, next page).

Part 2: Meiosis

7. Follow steps 1 to 3 from part 1.