Cell Structure (Edexcel IGCSE Biology)

Plant and animal cells have some features in common and some differences.

(i) Which of these structures is not found in animal cells?

(1)

(ii) Which of these substances is a carbohydrate stored in plant cells? 

(1)

The diagram shows a leaf palisade mesophyll cell.

(i) Describe the function of the parts labelled A, B, C and D.

(4)

(ii) Explain two ways that the structure of this palisade mesophyll cell is adapted for its function.

(2)

Separate: Biology Only

As an embryo develops, its cells differentiate.

Explain the importance of cell differentiation in the development of the growing embryo.

Separate: Biology Only

(i) Which of these is a feature of adult stem cells?

(1)

(ii) Adult stem cells or embryonic stem cells can be used in medical treatments.

Explain why the choice between these two types of stem cells can cause issues for doctors.

(2)

The diagram below shows a representation of a plant cell.

Describe the functions of structures P Q, and R.

(i) Label the diagram in part (a) with an S to indicate the location of the cell wall.

(1)

(ii) Describe the function of the cell wall.

(1)

Plants are one of the five groups of eukaryotes.

(i) Name another group of eukaryotes in which you might find structure P labelled in part (a).

(1)

(ii) State one other feature of the group named in part (i).

(1)

The cell shown below is found inside a salivary gland.

Suggest what can be concluded about the activities of the salivary gland cell from the image above.

Separate: Biology Only

The image below shows four specialised cells. Each cell is represented by a letter, A-D.

Identify one letter, from A-D, that corresponds to a cell that is described in each of the following statements. Each letter may be used once, more than once, or not at all.

(i) This is a plant cell.

(1)

(ii) This cell contains digestive enzymes.

(1)

(iii) This cell is motile (moves around).

(1)

(iv) This cell is involved in co-ordination of the body's activities.

(1)

Separate: Biology Only

Each of the cells shown in part (a) began its life as a stem cell.

Describe how a stem cell can give rise to the cell types shown in part (a).

Separate: Biology Only

Muscular dystrophy is a genetic condition in which patients lose muscle mass, leading to muscle weakness.

A clinical trial was carried out to investigate the effectiveness of bone marrow-derived stem cell treatment on muscle regeneration in muscular dystrophy patients.

(i) Bone marrow-derived stem cells are extracted from bone marrow.

Explain the abilities of stem cells taken from bone marrow.

(2)

(ii) Suggest how stem cells could be used to treat muscle wasting.

(3)

Separate: Biology Only

The graph below shows some of the results from the trial.

(i) Identify the dependent variable in this trial.

(1)

(ii) Suggest how the researchers might have measured the dependent variable identified in part (i).

(2)

(iii) Calculate the percentage of participants that showed a large muscle mass improvement in the trial. Give your answer to 1 decimal place.

(2)

Separate: Biology Only

A medical student concluded from these results that stem cell therapy would be an effective treatment for muscular dystrophy.

Evaluate the student's conclusion.

Separate: Biology Only

The image below shows a microscope image of the surface of a plant root.

(i) Name structure X.

(1)

(ii) Name two structures that would be present in structure X that would not be found in an animal cell.

(2)

The actual length of an object in a magnified image can be calculated using the following formula:

Calculate the actual length of structure X shown in part (a).

Measure structure X from the tip to the point at which the upper edge joins the main part of the root.

Give your answer in mm.

Separate: Biology Only

Suggest why the lack of a fully developed structure X could be damaging to a plant.

A student uses a light microscope to look at a human cheek cell.

The student makes this drawing of the cell.

Name the organelle shown in the drawing.

Mitochondria are organelles that are too small to be seen using a light microscope.

The drawing shows a mitochondrion that has been magnified.

The actual length of this mitochondrion is 6 μm.

[1 μm = 0.001 mm]

Calculate the magnification of this drawing.

The table gives information about mitochondria in different human cells.

(i) What is the mean number of mitochondria per μm³ in a heart muscle cell?

(1)

(ii) Comment on the differences in the data for the sperm and for the egg.

(3)

The image below is an electron microscope photograph of a cell.

(i) Name the group of organisms from which the cell shown in the image has been taken.

(1)

(ii) Explain how you identified the group of organisms in part (i).

(1)

Structure Y in part (a) is a starch granule.

Explain why structure Y is present inside structure X in the image in part (a).

Name three structures that are not clearly identifiable in the image in part (a) that you would expect to find inside cells from this group of organisms.

The cell in part (a) has been magnified 7.5 x 10³ times, and the image of the nucleus has a diameter of 6.5 cm.

Use the formula below to calculate the actual diameter of the nucleus. Give your answer in μm.

Note that 1 μm = 0.001 mm 

Separate: Biology Only

The image below is a representation of an electron microscope photograph of part of a sperm cell.

Name structures X, Y and Z labelled in the image.

Separate: Biology Only

Label two additional features on the image in part (a) with descriptions that explain how the features aid the sperm cell in its function.

Separate: Biology Only

Sperm cells are produced in the testes in a process known as spermatogenesis. A summary of spermatogenesis is shown in the image below.

(i) Label the image above with a letter D to indicate where the process of differentiation is occurring.

(1)

(ii) Explain what is taking place at letter D in order for differentiation to occur.

(2)

Spermatogonial stem cells (SSCs) can be used to treat male infertility.

(i) Suggest how SSCs could be used to treat male infertility.

(2)

(ii) Some research in mice has suggested that SSCs have the ability to become many different cell types.

Evaluate the potential use of SSCs in stem cell therapy.

(3)

The diagram below shows three different cells.

Calculate the size ratio of the bacterial cell compared to the liver cell and mesophyll cell.

The electron microscope image below shows a section from the inside of a liver cell...

Bochimoto H, Matsuno N, Ishihara Y, Shonaka T, Koga D, Hira Y, et al., CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons

(i) Name the organelles indicated by X.

(1)

(ii) Use information in the image to suggest the possible cell activities that take place inside a liver cell.

(2)

Separate: Biology Only

The liver is known to have a strong regenerative ability, meaning that when the liver is damaged it can regenerate itself within days. This regenerative ability is thought to be due to several types of adult stem cells present within and around the liver.

Contrast adult stem cells with stem cells taken from an embryo.

Separate: Biology Only

Scientists researching the regenerative capacity of the liver have identified a chemical signalling pathway inside liver cells that prevents the liver from growing too large when it regenerates. This chemical signalling pathway has been named 'Hippo'.

A recent discovery has shown that switching off the Hippo signalling pathway reverses the differentiation process, resulting in de-differentiated liver cells.

Suggest what this discovery could mean for the development of stem cell therapies.

Separate: Biology Only

The image below shows a light microscope photograph of part of a plant root.

Berkshire Community College  Bioscience Image Library, CC0, via Wikimedia Commons

(i) Name the type of specialised plant cell visible in the image.

(1)

(ii) Explain how the process of differentiation has allowed the cell in the image to carry out its specific function in plants.

(4)

A group of scientists carried out a study to investigate the starch content of roots in a species of grass at four points throughout the year. 

Their results can be seen in the graph below.

(i) Explain why the grass roots contain starch.

(2)

(ii) Explain how the starch found in the roots of grass species helps to support growth of the grasses.

(2)

(i) Calculate the percentage change in stored starch from January to October in the graph in part (b).

(2)

(ii) Suggest an explanation for the change calculated in part (i).

(3)