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Revising a-level Biology: Plants ‘r’ mint Introducing mint


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Revising A-level Biology: Plants ‘r’ mint

Introducing mint
In this revision pack, you will revise information you’ve studied at AS and A2. You’ll look at one particular living organism, mint, and see how this can be linked to the topics that you’ve already studied.

Aims

  1. To develop your breadth of knowledge (including AS topics) and your ability to apply both AS and A2 knowledge in new contexts.



  1. To help you make links between different topics and modules to encourage synoptic thinking.



Introducing mint
All mint plants belong to the genus Mentha, There are 18 recognised species of Mentha, with numerous varieties and a further 11 hybrids (created by crossing two different species). They grow in the wild on every continent except Antarctica, and are noted for their production on essential oils. They have been used traditionally for more than 2000 years as a source of medical remedies, flavourings, fragrances and even as a source of insecticides.
Mint plants are currently one of the most important commercial herbs grown, as the essential oils they produce are of high economic value. The most important commercial mint species are Mentha x piperita (peppermint), Mentha spicata (Native spearmint), Mentha x gracilis (Scotch spearmint) and Mentha canadensis (cornmint). Both Native and Scotch Spearmint are mainly produced in North America and China; peppermint oil is produced in the USA and India, while cornmint oil is mainly produced in India. Globally, over 40,000 tonnes of mint oils are produced per annum, with a value of over $800 million.
The essential oils produced by different mint plants are a complex mix of alcohols, monoterpenes and other hydrocarbons, oxides, esters, aldehydes and ketones and to a lesser extent carboxylic acids. Peppermint oil is mainly composed of L-L-menthol and L-menthone; cornmint oil is mainly composed of L-menthol and spearmint oil is mainly composed of L-carvone.
Other important mint oils include pennyroyal oil (an oil rich in the ketone D-pulegone), produced by Mentha pulegium, and bergamot oil, produced by Mentha aquatic var. citrata oil, which is rich in linalool and linalyl acetate.
The essential oils produced by mint plants are secreted by specialised cells and stored in circular structures called trichomes. These are small glandular outgrowths of the leaf epidermis. The natural role of these oils is to inhibit the growth of other competitor plant species (allelopathy), and to protect the mint plants from attack by insects and pathogens such as bacteria and fungi.
autoshape 7311

Wrigley’s peppermint flavoured chewing gum was first



marketed in 1893, in the same year that Colgate

introduced mint-flavoured toothpaste.




Information kindly supplied in 2013 by Brian Lawrence, editor of Mint -The Genus Mentha. CRC Press (2007). Lawrence (ed).

Find out more about the historical and commercial uses of mint plants and the essential oils they produce. Place your summary here – in any form that suits you (e.g. written; pictorial).

Consider food and drink, fragrances, medicines and any other uses you can find. (10 marks)


Mint hint: do an internet search using key words on page 1 to help you.

There are plenty of mint sources out there!

Food & Drink:

Fragrances:

Medicines:

Other:

.



Science & Plants for Schools: www.saps.org.uk (2013)

Revising A-level Biology: Plants ‘r’ mint




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