Stem cells

Coronary heart disease (CHD) is a type of cardiovascular disease.

Stem cells can be used to treat patients who have CHD.

The stem cells differentiate into cells of coronary arteries or heart muscle cells.

A patient with CHD was treated with stem cells.

The patient said:

‘Before the treatment, I was always tired. Now I can run.

There was a gradual improvement in my health and 3 months after the treatment I felt fit.’

Stem cells for the treatment of CHD can come from the patient or from a donor.

Describe why using stem cells from the patient is more successful than using stem cells from a donor.

Figure 7 shows an oak tree.

The binomial name of the oak tree is Quercus robur.

What is the genus name of the oak tree?

Tick (✓) one box.

Oak

Quercus

Robur

Other species of tree are in the same genus as Quercus robur.

What does it mean if two species of tree are in the same genus?

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The two species are always found in the same place.

The two species are closely related to each other.

The two species look exactly the same.

Oak trees grow at points where cells can divide.

Growth in oak trees happens at the tips of the branches.

Name the type of tissue at the tips of the branches.

Oak trees reproduce by sexual reproduction to produce seeds.

An acorn is a nut that contains a seed.

The seed may become a new oak tree.

Which process produces the cell that grows into the seed?

Tick (✓) one box.

Evolution

Fertilisation

Translocation

One type of insect lays eggs in acorns.

The insect eggs cause the acorn to grow abnormally.

The abnormal growth is called a gall.

Insect embryos grow inside the gall.

Figure 8 shows a normal acorn and an acorn that has grown a gall.

The gall is made from oak tree cells that have divided.

The cells of the gall contain two sets of chromosomes.

Which process produces the cells of the gall?

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Circulation

Digestion

Mitosis

The insects have changed over time and caused a gall to grow on acorns.

The gall increases the chance of survival of the insects inside the gall.

What name is given to the process of the insects changing over time?

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Clone production

Evolution

Inbreeding

The oak tree transports water and nutrients to the insect embryos inside the gall.

Water moves from the roots to the leaves.

Name the process that moves water from the roots to the leaves.

This question is about plant tissues.

Plant meristem tissue is found in the growing tips of shoots and roots.

Name two processes in plants that only occur in meristem tissue.

An acorn is a nut that contains the seed of an oak tree.

When one type of insect lays an egg in an acorn, the acorn grows abnormally.

The abnormal growth is called a gall.

An insect embryo grows inside the gall.

Figure 8 shows a normal acorn and an acorn that has grown a gall.

The seed in an acorn forms from one original cell with two sets of oak tree chromosomes.

The original cell in each seed was produced by sexual reproduction.

The gall has cells that contain two sets of oak tree chromosomes.

Compare the process that produced the original cell in each seed with the process that produced cells in the gall.

The insect embryo inside the acorn:

causes the growth of the gall

uses nutrients from the gall to grow

causes lignin to form around the outside of the gall.

The lignin around the gall protects the acorn from being eaten by herbivores.

Which other structure in the oak tree contains lignin?

Tick (✓) one box.

Phloem

Root hair cells

Xylem

Many years ago, a mutation of an insect embryo led to the embryo causing lignin production in an acorn.

Explain how the mutation could have produced a population of insects that all cause lignin production.

This question is about plants.

Meristem is a specialised tissue found at the tips of shoots and roots.

What is the function of meristem tissue?

Tick (✓) one box.

Cell division

Fertilisation

Transpiration

Xylem tissue and phloem tissue are found in plants.

Cells in phloem tissue contain sugars.

Table 1 shows some features of xylem tissue and phloem tissue.

Complete Table 1.

Put one tick (✓) in each row to show if the feature is true for:

both xylem and phloem.

Stomata are tiny holes in the surface of leaves.

Guard cells surround the stomata.

Figure 2 shows the shape of guard cells around stomata at different times of the day.

Figure 2

Guard cells control water loss from the leaf.

Explain what happens to the guard cells to increase water loss from the leaf.

Use Figure 2.

Stem cells are found in human embryos and in meristem tissue.

Which organisms is meristem tissue found in?

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Animals

Bacteria

Plants

New cells are produced during the formation of an embryo.

Figure 14 shows how a human baby is formed.

Some people believe using embryonic stem cells in medical research is unethical.

Give one reason why.

Bone cells divide to repair damage.

Give one other reason why bone cells divide.

Scientists tested a new drug to treat tumours in mice.

All the mice had the same type of tumour.

This is the method used.

1. Inject six mice with the drug once a day for 24 days.

2. Measure the volume of the tumour every 4 days.

3. Repeat steps 1 and 2, injecting a new group of mice with the drug twice a day.

Figure 15 shows the results.

Six other mice were given an injection that did not contain the drug.

Why did the scientists use mice that were not given the drug?

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As a clinical trial

As a control

As an anomaly

Describe how the drug injected once a day and the drug injected twice a day affected the volume of the tumour.

Use data from Figure 15.

Plants have different tissues that are adapted for special functions.

One plant tissue is meristem tissue.

Meristem tissue:

is made of meristem stem cells

is found in the growing areas of a plant

contains the cells that divide as a plant grows.

Figure 12 shows how specialised leaf cells are produced from meristem cells.

Meristem cells divide and then form specialised cells.

Cells become specialised during process X.

Name process X.

Describe two changes that can happen in a plant because meristem cells divide.

Scientists used a microscope to investigate cell division in a plant shoot.

Figure 13 shows the plant shoot.

The percentage of cells dividing by mitosis was estimated.

This is the method used.

1. Take a tissue sample from section A of the plant shoot and view 100 cells.

2. Count how many of the 100 cells are dividing by mitosis.

3. Repeat steps 1 and 2 for sections B, C and D of the plant shoot.

Table 8 shows the results.

Explain the results in Table 8.

Phloem tissue and xylem tissue are part of a plant’s transport system.

What is the name of the process that transports dissolved sugars around a plant?

Figure 14 shows a section of phloem tissue in a leaf.

Describe two ways the structure of phloem cells is different from the structure of xylem cells.

Dissolved sugar moves from the leaf cell into the phloem cell.

In Figure 14:

the concentration of sugar in the leaf cell is 4 mg per dm³

the concentration of sugar in the phloem cell is 118 mg per dm³.

The companion cell is needed to move sugar from the leaf cell into the phloem cell.

Explain why.

Adult stem cells are found in human bone marrow.

Bone marrow stem cells can differentiate into many types of blood components.

Figure 7 shows the components the bone marrow stem cells can differentiate into.

Name the component of the blood labelled A.

Damage to the bone marrow will lead to a reduction in the number of blood components produced in a person.

Describe the effect a reduction of component A will have on the person.

A person has 5.1 × 10⁹ red blood cells per cm³ of blood.

The person has 4.25 dm³ of blood in their body.

A total of 2.0 × 10¹¹ of the red blood cells are replaced each day.

Calculate the percentage of red blood cells that are replaced each day.

1 dm³ = 1000 cm³

Explain why red blood cells cannot divide by mitosis.

The different components of the blood can be used to treat different medical conditions.

Table 6 gives information about: blood from blood donation by volunteers the production of red blood cells from stem cells in laboratories.

Evaluate the use of blood donation to provide blood components compared with using stem cells to provide blood components.

Use information from Table 6 and your own knowledge.

A plant shoot is made of several tissues.

What is a tissue?

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What is the name of the tissue at the growing tip of a plant shoot?

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Plant cells divide by mitosis so that the plant can grow.

Give one other reason plant cells divide by mitosis.

Do not refer to growth in your answer.

Figure 9 shows a cell cycle.

Which two processes happen during cell growth in the cell cycle?

Tick (✓) two boxes.

In mitosis and meiosis cells divide to produce new cells.

Cell division by meiosis produces gametes.

Figure 10 shows a cell dividing by mitosis and a different cell dividing by meiosis.

Describe how the cells produced by mitosis are different from the cells produced by meiosis.

Use information from Figure 10.

A scientist investigated cell division in the growing tip of a plant shoot.

The scientist recorded data at different distances from the tip of the shoot.

Table 6 shows the results.

Give two conclusions from the data in Table 6.