Mitosis

Figure 10 shows the number of new cases of chlamydia diagnosed in England from 2013 to 2022.

Which type of organism causes chlamydia?

Calculate the increase in the number of new cases of chlamydia diagnosed from 2020 to 2022.

_........ cases

Tuberculosis is a disease that is spread through airborne droplets.

Give two ways of reducing or preventing the spread of tuberculosis.

Obesity is a risk factor for some non‑communicable diseases.

State why liver disease is a non-communicable disease.

The waist‑to‑hip ratio can be used to show if excess weight is a health risk.

An adult has a waist measurement of 80 cm and a hip measurement of 90 cm.

Calculate the waist‑to‑hip ratio for this adult, using the equation:

Give your answer to two decimal places.

waist‑to‑hip ratio_........

Figure 11 shows the health risk of some waist‑to‑hip ratios.

Explain the health risk for a female with a waist‑to‑hip ratio of 0.75.

Cancer occurs when cell division by mitosis is uncontrolled.

Describe the properties of cells produced by mitosis.

Tuberculosis is a disease that is spread through airborne droplets.

Give two ways of reducing or preventing the spread of tuberculosis.

Obesity is a risk factor for some non‑communicable diseases.

State why liver disease is a non-communicable disease.

The waist‑to‑hip ratio can be used to show if excess weight is a health risk.

An adult has a waist measurement of 80 cm and a hip measurement of 90 cm.

Calculate the waist‑to‑hip ratio for this adult, using the equation:

Give your answer to two decimal places.

waist‑to‑hip ratio_........

Figure 1 shows the health risk of some waist‑to‑hip ratios.

Explain the health risk for a female with a waist‑to‑hip ratio of 0.75.

Cancer occurs when cell division by mitosis is uncontrolled.

Describe the properties of cells produced by mitosis.

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.

When one cell goes through the stages of the cell cycle, two cells are produced.

Figure 7 shows the three stages of the cell cycle.

*(i) Describe the three stages of the cell cycle shown in Figure 7.

State what happens to the cell cycle in cancerous cells.

The production of more cells contributes to the growth of an animal.

Which other process is needed for the growth of an animal?

A parent is concerned that their child is not growing as much as other children.

Describe how a doctor might determine if the child is growing as expected.

Apple trees show genetic variation.

State one possible cause of genetic variation in apple trees.

The colour of an apple is an observable characteristic.

Which is the term for an observable characteristic?

Name the type of reproduction that produces genetically identical organisms.

Grafting is a technique used to grow some varieties of apple tree.

Figure 9 shows apple tree shoots grafted on to a rootstock.

Grafting can be used to produce apple trees that are genetically identical.

Give one advantage and one disadvantage of growing genetically identical apple trees.

advantage

disadvantage

As apples ripen, enzymes convert starch into sugars.

Devise a method to find the optimum pH of an enzyme that breaks down starch.

You may use standard laboratory equipment and the solutions listed in the box.

The optimum pH of an enzyme is pH 6.

Explain why this enzyme would not work at pH 10.

Name the type of reproduction that produces genetically identical organisms.

Grafting is a technique used to grow some varieties of apple tree.

Figure 1 shows apple tree shoots grafted on to a rootstock.

Grafting can be used to produce apple trees that are genetically identical.

Give one advantage and one disadvantage of growing genetically identical apple trees.

advantage

disadvantage

As apples ripen, enzymes convert starch into sugars.

Devise a method to find the optimum pH of an enzyme that breaks down starch.

You may use standard laboratory equipment and the solutions listed in the box.

The optimum pH of an enzyme is pH 6.

Explain why this enzyme would not work at pH 10.

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.

Figure 7 shows a height percentile chart for boys.

The numbers on the right-hand side of the graph show the percentiles of the population for each growth curve.

A 10-year-old boy has a height of 140 cm.

Which is the percentile range for height for this boy?

State how percentile charts are used.

As we grow, we make new cells by mitosis and meiosis.

The cells that are made can become specialised.

Figure 8 shows a diagram of a sperm cell.

Describe two ways that the sperm cell is specialised.

Complete the table to show the results when a cell divides by mitosis or meiosis in humans.

Human body cells, except gametes, have 23 pairs of chromosomes.

The tips of plant roots are where many cells are dividing by mitosis.

Which term describes the area of a root where many cells are dividing by mitosis?

Plant root cells contain an enzyme that joins glucose molecules together to make starch.

Devise a plan to investigate the effect of pH on the activity of this enzyme.

A student was investigating mitosis in the roots of a garlic plant.

Describe how the student could prepare a microscope slide to show mitosis in the growing roots of a garlic plant.

Describe what is produced when a single cell divides by mitosis.

The student observed 89 cells on the microscope slide.

Figure 4 shows the number of cells at each stage of the cell cycle.

Use this equation to calculate the mitotic index for this slide.

Give your answer to three significant figures.

Mitotic index_........

The mitotic index is often used in the diagnosis of cancer.

State the effect of cancer on cell division.

Figure 1 shows a cell from an onion root tip.

This cell is dividing by mitosis.

Which structure is labelled Z?

Mitosis produces new cells.

Give two reasons why mitosis is important in living things.

Draw one straight line from each stage of the cell cycle to its description.

A student is preparing a microscope slide of plant cells.

State what can be added to the slide to make the plant cells more visible.

The microscope has two lenses:

• an eyepiece lens with ×10 magnification

• an objective lens with ×40 magnification

Which is the total magnification of this microscope?

Name one part of a light microscope that can be moved to obtain a clear image of plant cells.

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.

Cancer Research UK found that many people do not realise that obesity is linked to an increased risk of developing cancer.

In the body, fat tissue sends signals that cause other cells to divide.

Describe how this could cause cancer to develop.

Cell division occurs during the cell cycle.

During which stage of the cell cycle is DNA replicated?

Obesity is linked to 1 in 20 cases of all types of cancer.

Approximately 13% of cases of bowel cancer are caused by obesity.

Determine how the impact of obesity on bowel cancer compares to the impact of obesity on all types of cancer.

Two men have the same mass of 80 kg.

One man’s BMI is categorised as normal weight, the other man’s BMI is categorised as obese.

Explain why the men have different BMI values.

Obesity can also cause cardiovascular disease to develop.

Describe the different treatments available for cardiovascular disease.

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.

James Watson and Francis Crick built a model that showed that DNA has a double helix structure.

Which statement about DNA is correct?

Figure 6 shows the percentage of each base in human DNA.

Describe how this data provides evidence for base pairing in DNA.

A scientist obtained a mass of 0.0062 nanograms of DNA from a diploid human cell.

Calculate the mass of DNA the scientist should obtain from a haploid human cell.

Give your answer in picograms.

(1 nanogram = 1000 picograms)

_........ picograms

A student used the method shown in Figure 7 to compare the mass of DNA extracted from strawberry fruit cells and from kiwi fruit cells.

State why ethanol is used.

State two variables the student needs to control when using this method to compare the mass of DNA from these two fruits.

The student repeated the experiment.

Give one reason why.

Mitosis and meiosis are processes that produce new cells.

Compare the outcomes of mitosis and meiosis.

A scientist obtained a mass of 0.0062 nanograms of DNA from a diploid human cell.

Calculate the mass of DNA the scientist should obtain from a haploid human cell.

Give your answer in picograms.

(1 nanogram = 1000 picograms)

_........ picograms

A student used the method shown in Figure 1 to compare the mass of DNA extracted from strawberry fruit cells and from kiwi fruit cells.

State why ethanol is used.

State two variables the student needs to control when using this method to compare the mass of DNA from these two fruits.

The student repeated the experiment.

Give one reason why.

Mitosis and meiosis are processes that produce new cells.

Compare the outcomes of mitosis and meiosis.

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.