Cell Structure (Edexcel IGCSE Biology: Double Science)

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

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

(1)

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 

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

Name the organelles indicated by X.

(1)

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

(2)

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.

Explain why the grass roots contain starch.

(2)

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

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

(2)

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

The diagram below shows a representation of a plant cell.

Describe the functions of structures P Q, and R.

(3)

(b)

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.

(1)

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.

(2)