Mitosis

Cancer occurs when there is uncontrolled cell division.

Which two factors can cause cancer?

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What type of cell division occurs in cancerous cells?

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Complete the sentences.

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Figure 4 shows the cell cycle.

What percentage of the time taken for the cell cycle does the cell growth stage take?

Use Figure 4.

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What happens during stage X of the cell cycle in Figure 4 ?

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Figure 5 shows an animal cell during cell division.

Name structure Z in Figure 5.

The image of the cell in Figure 5:

• is magnified 800 times

• has a width of 50 mm.

Calculate the real width of the cell in Figure 5.

Give your answer in micrometres (µm).

Use the equation:

1 mm = 1000 µm

Some drugs can treat cancer.

Complete the sentences.

Choose answers from the box.

In drug trials some patients are given a tablet which does not contain the drug.

What name is given to the tablet that does not contain the drug?

Cancer is caused by changes in cells that result in uncontrolled cell division.

Before a cell begins to divide, its DNA replicates to form two copies of each chromosome.

Describe one other change that occurs in a cell before the cell begins to divide.

Figure 8 shows a cell during one of the stages of cell division.

Name structure Z in Figure 8.

Structure Y in Figure 8 is a cylinder.

For structure Y:

• real volume = 24 500 000 nm³

• real radius = 125 nm.

The length of a cylinder is calculated using the equation:

The length of the image of structure Y in Figure 8 is 4 mm.

Calculate the magnification of structure Y in Figure 8.

Use π = 3.14

Magnification = ×

Figure 9 shows some of the stages of cell division.

Some cancer drugs prevent cell division.

Drug X prevents the fibres from attaching to the replicated chromosomes in stage 1.

Explain why a cell cannot complete division when affected by drug X.

Give the reason why a drug that stops cell division helps to treat cancer.

New cancer drugs are tested in clinical trials.

Preclinical testing happens before clinical trials.

What is involved in preclinical testing of drugs?

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Malaria is caused by a protist.

The protist is passed from one person to another person by mosquitos.

Which term describes the mosquito?

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The malarial protist is a eukaryotic cell.

Figure 2 shows a malarial protist.

Give two features of the malarial protist that show the cell is eukaryotic

and not prokaryotic.

Which organism is prokaryotic?

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The malarial protist reproduces asexually.

What is a feature of asexual reproduction?

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Mitosis occurs in the malarial protist during asexual reproduction.

The protist has 14 chromosomes.

How many chromosomes will each new protist cell have after mitosis?

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When a person has malaria, the protists destroy red blood cells.

What change would happen in the blood of a person with malaria?

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It is estimated that 210 million people are infected with malaria every year. Half of these infected people survive the disease.

Calculate how many people would survive the disease in 3 years if the estimate is correct.

Give your answer in standard form.

The spread of malaria can be controlled by using mosquito nets to avoid being bitten.

Describe two other ways that people can reduce the chance of being bitten by mosquitos.

Do not refer to mosquito nets in your answer.

Different types of disease may interact.

Scientists studied how having disorder S interacts with malaria.

The scientists calculated the chance of children with disorder S getting malaria.

Table 4 shows the results.

Describe the trend shown in Table 4.

Use data from Table 4.

This question is about food and digestion.

Proteins are needed to make new body cells by mitosis.

Give one reason why a person needs new body cells.

What are proteins made of?

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Which chemical is used to test for protein in food?

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What colour would be seen in a positive test for protein?

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Enzymes break down food molecules in the human body.

Characteristics of enzymes are linked to their function.

Draw one line from each characteristic to its effect on enzyme function.

Figure 3 shows how pH affects the rate of breakdown of protein.

Which pH does enzyme Y work fastest at?

Explain why enzyme X works best in the stomach.

Complete the sentences.

Choose answers from the box.

Enzyme Y does not break down protein at pH 6 because the shape of the enzyme has changed.

The part of the enzyme that changes shape is

the.

The change in shape means the enzyme cannot bind to

the.

Amylase is an enzyme which breaks down starch.

A student investigated the effect of pH on the rate of starch breakdown by amylase.

Figure 4 shows some of the apparatus the student used.

Describe a method to investigate the effect of pH on the rate of starch breakdown by amylase.

You should include the apparatus shown in Figure 4.

The protist that causes malaria is passed from one person to another person by mosquitos.

What term describes an organism that passes a pathogen from one person to another person?

Figure 7 shows the malarial protist.

The malarial protist is a eukaryotic cell. Describe three ways the structure of the malarial protist is different from the structure of a prokaryotic cell. Do not refer to size in your answer.

During one stage of malaria infection, the malarial protists enter red blood cells and cause them to burst. Explain why the bursting of red blood cells causes tiredness.

The malarial protist reproduces sexually and asexually during a life cycle. Complete Table 3 to give three differences between sexual reproduction and asexual reproduction. One difference has been completed for you.

One drug for treating malaria prevents mitosis occurring in the malarial protist. The drug stops the synthesis of new DNA bases in the cell. Suggest how the drug prevents mitosis occurring.

Describe the process of cell division by mitosis.

Different types of disease may interact. Scientists studied the incidence of malaria infections in children:

• with disorder S

• without disorder S.

The incidence of malaria in children with disorder S was calculated as a percentage of the incidence in children without disorder S. Table 4 shows the results.

Describe what the results in Table 4 show about the interaction between disorder S and malaria.

Figure 1 shows animal cells.

Some of the cells are dividing by mitosis for growth and repair.

What fraction of the cells in Figure 1 is dividing by mitosis?

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The cells which are not dividing in Figure 1 each contain 10 chromosomes.

One of these cells divides by mitosis to produce two new cells.

How many chromosomes will each new cell contain after mitosis?

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Cells divide in a series of stages called the cell cycle.

Complete the sentences.

Choose answers from the box.

After the chromosomes have been pulled to each end of the cell, the

Figure 2 shows the time taken to complete different stages of the cell cycle.

Which stage of the cell cycle takes the most time?

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What percentage of time in the cell cycle is stage A ?

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Stem cells divide by mitosis.

Scientists can use stem cells from an embryo to create heart cells in a laboratory.

Which organ system contains heart cells?

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Name one medical condition that could be treated using heart cells created from an embryo.

Give one reason why a patient may not want to be treated with heart cells created from an embryo.

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Plants and animals have many defence responses.

Table 5 shows some plant defences. Identify whether each defence is a chemical response or a physical response. Tick (✓) one box in each row.

Mimicry is a mechanical adaptation seen in both plants and animals.

Figure 5 shows two insects.

Hornets are insects that sting other animals and cause pain. Hornet moths do not sting other animals. Suggest how mimicry helps the hornet moth survive.

Adult hornet moths lay eggs that hatch into larvae.

Figure 6 shows the larvae of a hornet moth.

The larvae of the hornet moth:

• live inside the roots of trees

• use the tree roots as a source of food

• cause damage to the tree roots.

Explain why a tree might die if the roots of the tree are damaged.

The larvae of the hornet moth form when fertilised eggs divide by mitosis. Describe how mitosis produces two genetically identical cells.

The cells which are first formed from the fertilised eggs of the hornet moth are stem cells. Name the process by which these stem cells then form specialised cells.

This question is about cell division.

Which process makes two identical new body cells for growth and repair? Tick (✓) one box.

Figure 5 shows the three stages of a cell cycle.

Draw one line from each stage of the cell cycle to what happens during that stage. Stage of cell cycle What happens during that stage

What percentage of the total time for the cell cycle is taken by stage 1?

A cell divides to form two new cells every 24 hours. How many days will it take for the original cell to divide into 8 cells? Tick (✓) one box.

The chromosomes contain the genetic material. Name the chemical which the genetic material is made from.

The genetic material is made of many small sections. Each section codes for a specific protein. What is one section of genetic material on a chromosome called? Tick (✓) one box.

Stem cells are cells which have not yet been specialised to carry out a particular job. Bone marrow cells are one example of stem cells. Explain how a transplant of bone marrow cells can help to treat medical conditions.

Figure 5 shows three types of cell.

Give two similarities between the prokaryotic cell and the eukaryotic cells in Figure 5.

Give three differences between the prokaryotic cell and the eukaryotic cells in Figure 5.

Calculate the ratio of the size of the bacterial cell to the size of the mesophyll cell.

Name the type of cell division that produces genetically identical body cells for growth and repair.

Figure 6 shows a cell cycle.

What percentage of the time for one cell cycle is represented by stage 2 and stage 3 together? Tick (✓) one box.

Describe what happens during each stage of the cell cycle.

An animal called an axolotl lives in water.

Figure 3 shows an axolotl.

Oxygen enters the axolotl’s bloodstream through the gills by diffusion.

What is diffusion?

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Describe how one feature of the axolotl’s gills increases the rate of diffusion of oxygen.

Use information from Figure 3.

If a gill of an axolotl is removed, stem cells in the damaged area will divide and a new gill will grow.

Complete the sentence.

Choose the answer from the box.

When stem cells specialise to produce gill cells, this process is

known as.

Complete the sentence.

Choose the answer from the box.

To grow a new gill the stem cells divide by.

Which one of the following does not contain stem cells?

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Axolotls are small animals. Axolotls are used in stem cell research.

What are two advantages of using axolotls in stem cell research?

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Oxygen uptake in humans takes place in the lungs.

Figure 4 shows the human breathing system.

Where does oxygen enter the bloodstream?

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Name part E on Figure 4.

Which blood vessel carries blood to the lungs?

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This question is about the cell cycle.

Chromosomes are copied during the cell cycle.

Where are chromosomes found?

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What is the name of a section of a chromosome that controls a characteristic?

Figure 1 shows information about the cell cycle.

Which stage of the cell cycle in Figure 1 takes the most time?

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During mitosis cells need extra energy.

Which cell structures provide most of this energy?

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The cell cycle in Figure 1 takes two hours in total.

The cell growth stage takes 45 minutes.

Calculate the time taken for mitosis.

Figure 2 shows some cells in different stages of the cell cycle.

Which cell is not dividing by mitosis?

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Cell E in Figure 2 contains 8 chromosomes.

Cell E divides by mitosis.

How many chromosomes will each new cell contain?

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Why is mitosis important in living organisms?

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