1.1. Figure 1 shows cells from an onion root tip as seen using a light microscope.

Figure 1

(i) Identify the stages of mitosis shown in cell Q and cell R.

(1)

(ii) Describe two processes that occur in cells during prophase.

(2)

1 ....................................................

2 ....................................................

(iii) State the term used to describe the process which occurs after mitosis, when the cell divides into two.

(1)

(iv) The diameter of one cell in Figure 1 is 0.075 mm.

Which is this diameter in μm?

(1)

☐ A 0.75 μm
☐ B 75 μm
☐ C 750 μm
☐ D 75 000 μm

1.2. A student placed a prepared slide on the stage of a light microscope.

Describe how to adjust the microscope to view the slide at a magnification of ×400.

1.3. Arthritis is a condition that occurs when cells in joints get damaged or destroyed.

Stem cell therapy can be used to treat arthritis.

Discuss the benefits and risks of using stem cell therapy to treat arthritis.