Plant Structure & Function (Edexcel International A Level (IAL) Biology): Exam Questions

The stem of a plant contains structures involved in transporting substances and supporting the plant.

The photograph shows a section through part of the stem of a plant, as seen using a light microscope.

(i) Which of the labelled structures is sclerenchyma?

(1)

(ii) Which of the labelled structures is involved in transporting substances both up and down the plant stem?

(1)

(iii) Which of the labelled structures is involved in transporting calcium ions from the stem to the leaves?

(1)

(iv) Which of the following may have secondary thickening in the cell walls?

(1)

☐ A Phloem sieve tubes only
☐ B Phloem sieve tubes and sclerenchyma fibres
☐ C Xylem vessels only
☐ D Xylem vessels and sclerenchyma fibres

Plants require inorganic ions for growth.

In an investigation, groups of plants were watered with the same volume of a nutrient solution.

The solution contained all the required inorganic ions, but with different concentrations of magnesium ions.

The table shows the results of this investigation.

(i) Explain the importance of magnesium ions to plants.

(2)

(ii) Comment on the results of this investigation.

Use the information in the table to support your answer.

(4)

Plants contain many types of molecule.

(i) Which molecule is shown in the diagram?

(1)

(ii) Which is a feature of cellulose molecules?

(1)

(iii) Which molecule contains magnesium ions?

(1)

Plants contain tissues that have different functions.

(i) Name one tissue that gives the plant support and is also involved in the transport of water through the plant.

(1)

(ii) Name one fibre that gives the plant support but is not involved in the transport of water through the plant.

(1)

The Ulin tree (Eusideroxylon zwageri), is native to Brunei, Indonesia and the Philippines.

The photograph shows an Ulin tree.

This species of tree is endangered and the export of wood from these trees is forbidden from some countries. Suggest three reasons why this species of tree is endangered.

1............................................

2............................................

3............................................

Trees, and other plants, contain phloem vessels and sclerenchyma fibres. The photograph shows sieve plates in the phloem of a plant.

magnification ×200

(i) Calculate the width of the phloem vessel along the line XY in micrometres. The line XY measures 3.8cm when the photograph is printed onto paper.

Give your answer in standard form.

(3)

(ii) Describe the role of phloem.

(2)

(iii) How many of the following statements about mature sclerenchyma fibres are correct?

• they contain cellulose microfibrils

• they contain pits

• they contain cytoplasm

(1)

The roots of plants contain phloem and xylem vessels, as shown in the diagram.

Give three differences between the distribution of phloem and xylem in the root compared with their distribution in the stem.

1...............................................
2...............................................
3...............................................

Abaca plants are found in the Philippines.

The illustrations shows some mats made from abaca plant fibres.

Obsidi♠nSoul, Public domain, via Wikimedia Commons

Plant fibres include xylem vessels.

The photograph shows some xylem vessels, as seen using a light microscope. 

(biophotos), CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons

A stain was added to the xylem before viewing using a microscope.

Give a reason why it is usual to stain specimens in microscopy.

Explain how the arrangement of cellulose molecules and secondary thickening in xylem vessels contributes to the physical properties of the cell wall.

The micrograph shows an organism known as Chlamydomonas, a unicellular photosynthetic organism found in freshwater environments.

Dartmouth Electron Microscope Facility, via Wikimedia Commons (opens in a new tab)

Identify the structures labelled B, D and G.

The two structures labelled D are slightly different in size and shape.

Suggest why this is the case.

Structure A is an amyloplast.

Which of the following correctly describes the function of an amyloplast?

The amyloplasts surround a darker structure known as the pyrenoid. The pyrenoid is a compartment that contains enzymes involved in photosynthesis.

Explain one possible advantage of these enzymes being contained within a compartment.

The scale bar shown in part (a) measures 1 cm and the diameter of the cell in the image measures 12.2 cm.

Calculate the actual diameter of the Chlamydomonas cell. Give your answer in μm.

The micrograph shows a cross section through plant tissue.

Berkshire Community College Bioscience Image Library, via Flickr (opens in a new tab)

(i) Identify structures X, Y and Z.

[3]

(ii) Identify the region of the plant from which this cross-section has been taken.

[1]

The structure labelled X in part (a) can be used to produce materials for human use.

Explain how this contributes to sustainability.

Cellulose and starch are both polysaccharides found in plant cells.

Compare and contrast the structure of cellulose and starch.

Describe the features of plant fibres that give them a high tensile strength.

The cassava root is an important food crop grown in the tropics.

The photograph shows organelles containing starch granules inside cassava root cells, as seen using an electron microscope.

(i) Name these organelles found in cassava root cells.

(1)

(ii) Explain how the structure of starch relates to its function.

(3)

The graph shows the mass of five food crops grown in Africa. It also shows the world production of these crops.

(i) Which is the percentage of the world cassava crop that is grown in Africa?

(1)

☐ A 33%

☐ B 34% 

☐ C 66%

☐ D 67%

(ii) It is predicted that the world maize production will increase by 2.3% in the following year.

Calculate the world production of maize in the following year.

Give your answer to the nearest whole number.

(1)

Answer ............................ million tonnes

Some plants contain chemicals that protect them from being eaten by animals.

These chemicals taste bitter and can be converted by enzymes into hydrogen cyanide.

Hydrogen cyanide inhibits respiration and can cause death.

Cassava can be grouped into two main varieties: bitter cassava and sweet cassava.
These varieties differ in the concentration of the bitter-tasting chemicals.

Processing of the cassava removes most of these chemicals.

The graph shows the mean dry mass of these cassava varieties when grown in the same conditions.

The table gives information about three crop plants.

Discuss the advantages and disadvantages of growing these three crop plants for human food.

Use the information in the question to support your answer.