Plant Structure & Function

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.

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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.

Explain the importance of magnesium ions to plants.

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(ii)

Comment on the results of this investigation.

Use the information in the table to support your answer.

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Plants contain many types of molecule.

Which molecule is shown in the diagram?

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Which is a feature of cellulose molecules?

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(iii)

Which molecule contains magnesium ions?

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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.

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(ii)

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

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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.

Trees, and other plants, contain phloem vessels and sclerenchyma fibres.

The photograph shows sieve plates in the phloem of a plant.

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• they contain cellulose microfibrils
• they contain pits
• they contain cytoplasm

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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.

Woese classified organisms into a three‐domain system.

Plant cells were classified into the Eukarya domain.

The diagram shows an incomplete cell from a plant.

Complete the diagram by drawing an amyloplast, a chloroplast and the tonoplast to show their location and relative size in this cell.

Label these three structures.

The photograph shows an organelle found in a plant cell, as seen using an electron microscope.

State the function of this organelle.

The other domains in the three‐domain system are Archaea and Bacteria.

Complete the table to show in which of the domains the following structures would be found.

Place an X in each appropriate box.

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.