IB Biology SL D2.1 Cell and nuclear division Question Bank

Antiretroviral drugs are used to treat Human Immunodeficiency Virus (HIV) infections. Zidovudine (ZDV) and nevirapine (NVP) are examples of antiretroviral drugs. There are concerns that these drugs may be toxic to body cells in mitosis. In a study using Allium cepa, root tips were exposed to the drugs for 96 hours at a range of concentrations. The control treatment was a drug concentration of $0 \mu \mathrm{~mol}$. In the graph, root lengths after the 96-hour treatment period are expressed as a percentage of the length of the control.

During the development of multicellular organisms, cells differentiate into specific cell lines. A study was carried out on the early stages of differentiation in cells from mouse embryos that were grown in cultures. Two differentiated cell lines were studied, one of inner embryonic tissue (endodermal cells) and the other of external embryonic tissue (nerve cells) after 48 and 96 hours of incubation in cell cultures. A culture of undifferentiated cells was used as a control group. Cell population growth was measured by changes in cell density in all three cell lines.

The cell theory states that cells come from pre-existing cells. What biological process allows this to occur?

The image shows a micrograph of a cell.

in_prophase,_metaphase,_anaphase,_telophase).jpg by Doc. RNDr. Josef Reischig, CSc.]

What explains the appearance of the cell in the micrograph?

This micrograph is from a dividing cell.

What is shown in this image?

The following shows a micrograph.

In what order do the events in mitosis occur?

In the micrograph, which letter points to a cell in anaphase?

How many chromosomes are there in a cell during anaphase of mitosis, if the diploid numberof the cell is 20 ?

The image shows cells in the different stages of mitosis. Which cell is in telophase?

Which is the sequence of events in mitosis?