Stem cells

Scientists think that chickens were domesticated from red junglefowl thousands of years ago.

Figure 4 shows some information about these birds.

Describe how selective breeding has produced chickens that lay large numbers of eggs.

Chickens have 78 chromosomes in each of their body cells.

These chromosomes are in pairs.

Which term describes a chicken body cell?

State the number of chromosomes found in the gametes produced by chickens.

Complete the table to compare the production of body cells and gametes.

One box has been completed for you.

Some animal cells are stem cells.

Describe the function of stem cells.

Figure 3 shows a diagram of a mouse sperm cell.

Which row of the table shows the functions of structure A and structure B?

The diploid chromosome number for a mouse is 40.

State the number of chromosomes in a mouse sperm cell.

After a mouse egg cell is fertilised, cell division produces a ball of genetically identical stem cells.

Which is the correct order for the stages of one cell division?

The genetically identical stem cells produce the cells that develop into an embryo.

Describe how stem cells produce the cells of an embryo.

Give one scientific reason why the bone marrow transplant in 1968 was from a sister to her brother.

Give one scientific reason why some people are opposed to the isolation of human embryonic stem cells.

Stem cells, with the properties of embryonic stem cells, can be produced from a patient’s own skin cells.

Discuss the benefits of using these stem cells to treat the patient.

State why the embryo of the pig must be engineered so it does not grow pig kidneys.

Explain why human stem cells are used for this process.

Figure 6 shows the number of organ transplants needed and the number of donors available in the USA from 1991 to 2018.

Compare the number of donors available with the number of organ transplants needed from 1991 to 2018.

Use information from the graph to support your answer.

State why scientists are genetically engineering animals for organ transplants.

*(c) Bacteria have been genetically engineered to produce human insulin since 1978.

Explain how bacteria can be genetically engineered to produce human insulin.

Figure 4 shows cells from an onion root tip as seen using a light microscope.

(Source: © Rattiya Thongdumhyu/Shutterstock)

Figure 4

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

Describe two processes that occur in cells during prophase.

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

The diameter of one cell in Figure 4 is 0.075 mm.

Which is this diameter in µm?

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.

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.

Figure 8 shows a banana plantation.

After the bananas have been harvested, the old plants are cut down.

The suckers then develop into mature plants producing the next crop of bananas.

The tip of each sucker contains a group of cells called a meristem.

Describe the function of a meristem in the growth of a plant.

A student took a sample of cells from a meristem to view under a light microscope.

Describe how the student would prepare a microscope slide using these cells.

Figure 9 is a drawing of a eukaryotic cell.

Structure Z is found in plant leaf cells.

Name structure Z.

Give one function of the mitochondrion.

*(c) DNA is found in the nucleus of cells.

Describe the structure of DNA and how it can be extracted from plant cells.

Figure 2 shows a banana plantation.

After the bananas have been harvested, the old plants are cut down.

The suckers then develop into mature plants producing the next crop of bananas.

The tip of each sucker contains a group of cells called a meristem.

Describe the function of a meristem in the growth of a plant.

A student took a sample of cells from a meristem to view under a light microscope.

Describe how the student would prepare a microscope slide using these cells.

Figure 3 is a drawing of a eukaryotic cell.

Structure Z is found in plant leaf cells.

Name structure Z.

Give one function of the mitochondrion.

Describe how a prokaryotic cell is different from the cell in Figure 3.

A student investigated mitosis in the root tip of a garlic plant.

Explain why the student used the tip of the root.

The student squashed the root tip on a microscope slide to spread out the cells.

The slide was placed on the stage of a microscope.

Describe how to use the microscope to obtain a clear image of the cells.

The student could not see the chromosomes inside the cells.

State what can be added to the root tip squash to make the chromosomes visible.

Figure 1 shows a root cell in a stage of mitosis.

Which stage of mitosis is shown in Figure 1?

Describe what is happening in Figure 1.

A student cut a piece of onion and placed it on a microscope slide.

The student then placed this slide on the stage of a light microscope and looked through the eyepiece.

No cells could be seen in the piece of onion.

Explain two ways this method could be improved to see details of the onion cells.

Figure 4 shows mitosis occurring in some plant cells.

The cells in Figure 4 were taken from a rapidly growing part of a plant.

Which part of a plant has rapidly dividing cells?

Which stage of mitosis is shown in cell R?

Describe two genetic similarities of the new cells that would be produced by cell Q in Figure 4.

The cells in Figure 4 were heated in hydrochloric acid.

State two safety precautions that should be taken when heating hydrochloric acid.

Explain one advantage of using an electron microscope to observe plant cells.

In 2012, two scientists were awarded the Nobel prize for their research on stem cells.

They showed that adult cells could be reprogrammed to become cells with the properties of embryonic stem cells.

Describe the possible benefits of this research.

Figure 8 shows four stages of mitosis, labelled P, Q, R and S.

Which is the correct order for these stages?

The stage of mitosis labelled S in figure 8 is

Interphase is part of the cell cycle.

Describe what happens during interphase.

Figure 9 shows a root tip with cells in different stages of mitosis.

The image was magnified 400 ×.

Explain how a magnification of 400 × can be obtained using the lenses on a light microscope.