Cell Structure & Organisation

All organisms contain one or more cells.

In which of the following is a cell membrane present?

(1)

In which of the following is a cell wall present?

(1)

Sailor’s eyeball (Valonia ventricosa) is a single-celled, spherical organism.

The diagram shows one of these cells. A ruler scale has been provided to show the diameter of the diagram when viewed on a screen.

The diameter of this cell is 25 μm.

Calculate the magnification of the diagram.

(2)

This cell contains chloroplasts.

State the function of these chloroplasts.

(1)

This cell is not a prokaryotic cell as it contains chloroplasts.

Give one other reason why this organism is not a prokaryotic cell.

(1)

The image shows part of two adjoining plant cells, as seen using an electron microscope.

Name the part labelled X.

(1)

(ii)

Explain the function of the part labelled X.

   (2)

Female mosquitoes feed on the blood of other animals to promote the development of their eggs. During this process, infected mosquitoes can transmit the Plasmodium parasite.

The Plasmodium parasite causes the disease malaria.

The photograph shows a female Anopheles mosquito.

A ruler has been included for scale. 

Alan R Walker, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Calculate the magnification of the Anopheles mosquito in this photograph.

Give your answer to one decimal place.

In 2017, an estimated 219 million people in 87 countries had malaria, and 435 000 of these people died.

Which of the following shows the percentage of infected people who died?

The fungus Metarhizium pingshaense infects Anopheles mosquitoes.

A student drew a labelled diagram of a fungal cell that was dividing.

State the function of a nucleolus.

(1)

(ii)

Give three differences in ultrastructure between this cell and a cell taken from the root of a plant.

(3)

Insecticides are chemicals used to kill insects.

Anopheles mosquitoes have developed resistance to the insecticides currently used.

Metarhizium pingshaense is a fungus that infects Anopheles mosquitoes.

Scientists in West Africa have genetically engineered (GE) this fungus using a gene from a spider.

When the GE fungus infects an Anopheles mosquito this gene becomes activated. A toxin is released, which kills the mosquito.

In an investigation, four huts each containing a group of 500 breeding pairs of mosquitoes were used.

Three different treatments used to kill mosquitoes were compared with a control group.

The walls and ceiling of the huts were sprayed with the treatment.

The table shows the number of adult mosquitoes in the first two generations of offspring from each hut after spraying.

Evaluate these three treatments.

Use the information in the question, and your own knowledge, to support your answer.

Eukaryotic cells contain cell organelles.

The diagram shows part of a eukaryotic cell, as drawn by a student.

The nuclear envelope, nuclear pores and rough endoplasmic reticulum are labelled.

(1)

After cell division, the plant cells produced increase in size.

Explain how these plant cells increase in size.