Integrated Science M2*U5*L6(b)

BEGIBEGINN

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Objectives

You should be able to: 1.define osmoregulation.2.describe the four types of plants based on their adaptations for osmoregulation.3.state the importance to plants of conserving/storing water.

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NOTE: For the activities in this slide show, you will be asked to type your responses in boxes. To do so, you must be in Slide Show View. You can insert and delete text in the box in Slide Show View.

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Introduction

The protoplasm of living organisms has a high percentage of water, so without water, living organisms would die.

Plants living in water, or those in hot, arid conditions where water is not readily available all the time, or in which there is a high concentration of solutes such as occurs in/near sea water, must adapt their structure and/or their various functions – or both - to ensure the conservation of needed water and prevent the upset of the osmotic balance of cell contents.

Without the right osmotic balance – the plant dies!Without the right osmotic balance – the plant dies!

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Surviving the salt

These Mangroves grow in wet, muddy soil at the sea -water's edge. If you look at the leaves, salt crystals are excreted on to their surfaces, and if you taste the sap – it’s very salty!

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How can they live with so much salt?

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Surviving the salt

Most trees cannot survive in water that has too much salt in it, but mangrove trees have a unique adaptation for dealing with the sea's salinity.

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Some mangroves are almost covered by salty sea water!

Read the ‘One ingenious plant’ to the end of ‘Roots that Multitask’ at: http://www.amnh.org/explore/science-bulletins/bio/documentaries/mangroves-the-roots-of-the-sea/what-s-a-mangrove-and-how-does-it-work

http://images.all-free-download.com/images/graphiclarge/grass_trees_hd_picture_165975.jpg

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Surviving the salt

Now, read the first four paragraphs at > http://www.naturia.per.sg/buloh/plants/mangrove_trees.htm

When they’re submerged in sea water, warty growths on mangrove roots filter out most of the salt as they take water in through their roots.

Some mangroves concentrate extra salt in old leaves (which turn yellow and die), and some are able to get rid of the salt by secreting it through the pores of special glands.

Source: http://wiki.answers.com/Q/Why_mangroves_live_in_salt_water?#slide=5

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Surviving drought

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How do they survive?

In contrast to mangroves, plants, such as these cacti and Acacia that live in places like along the Palisadoes strip or in the Hellshire area, grow in limited, dry, sandy soil, with little rainfall, a very high temperature and a hot, dry wind.

There is little soil moisture.

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Some water-conservation methods

Look at the Cactus stem and those leaves. Do they help you to answer that question?

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Succulent leaves of Sesuvium & Aloe

Succulent plant stem (Cactus)

Succulent plant stem (Cactus)

How do they survive?

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Osmoregulatory adaptations

The plants shown on the previous slides have adaptations that ensure osmoregulation.

Osmoregulation is the active regulation of the osmotic pressure of an organism’’s fluids to maintain the homeostasis (or constant unchanging balance) of the organism’s water content; that is, it keeps the organism's fluids from becoming too diluted or too concentrated.

Think and recall what you learned about osmosis in term 1.

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Source: http://en.wikipedia.org/wiki/Osmoregulation

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Osmoregulatory adaptations

Plants such as mangroves develop structural and physiological adaptations to regulate the osmotic balance of their cell contents – i.e. To carry out osmoregulation.

The cacti and other plants living along the hot, dry scrubland of the Palisadoes strip also develop special adaptive features for osmoregulation.

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Osmoregulatory adaptations – Types of plants

Depending on their habitat, plants can be grouped into four different types according to the osmoregulatory adaptations that they show either in their structure, functions, or both. Groups are as follows:

1. Halophytes2. Hydrophytes3. Xerophytes4. Mesophytes

Read the section on ‘Osmoregulation in Plants’ at > http://en.wikipedia.org/wiki/Osmoregulation

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Activity

1. When you open this video, click pause each time text appears so that you can read it properly >

http://www.youtube.com/watch?v=lBzHYzXjdToPlay it twice if necessary!2. In which group would you place the following plants?

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a. Mangrove = halophyteb. Cactus = xerophytec. Ackee tree = mesophyted. Water lily = hydrophyte

Groups:1. Halophytes2. Hydrophytes3. Xerophytes4. Mesophytes

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Activity: Hydrophytes

3. What adaptations do these water lilies show for living in water?

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The leaves float on the water surface and numerous stomata are present on the upper surface of the leaves facing the atmosphere to promote loss of water. The surface area of these leaves is very large to enable excessive water loss by transpiration.

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Feedback to Activity

FEEDBACK.2. (a) mangrove = halophyte (b) Catus = xerophyte (c ) an ackee tree = mesophyte (d) water lily = hydrophyte3. The leaves float on the water surface and numerous

stomata are present on the upper surface of the leaves facing the atmosphere to promote loss of water. The surface area of these leaves is very large to enable excessive water loss by transpiration

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Why is osmoregulation important to plants?

the habitat is dry, hot and desert-like.sandy/rocky soil does not hold much water. rainfall is scarce or only at certain times.adequate water is not available for photosynthesis and

hydration of the cell contents.habitat is completely aquatic.salinity of the habitat is high.

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1. Enables the plant to grow, develop, carry on respiration, photosynthesis and survive, even if:

2. It regulates and balances the uptake and loss of water and solutes so maintains homeostasis.

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Credits

http://www.mangrove.at/images/mangrove/forests/overwashed/overwashed%20mangrove%20forest.jpg

http://images.all-free-download.com/images/graphiclarge/grass_trees_hd_picture_165975.jpg

http://www.palmislandestates.org/images/environmental/mangroves.jpg http://scienceray.com/biology/botany/the-desert-saguaro/ http://www.cbd.int/doc/world/jm/jm-nbsap-01-p4-en.pdf http://keetsa.com/blog/wp-content/uploads/2009/06/aloe-vera-plant.jpg http://commons.wikimedia.org/wiki/File:Avicennia_germinans-salt_excretion.jpg http://wiki.answers.com/Q/Why_mangroves_live_in_salt_water?#slide=5 http://www.shutterstock.com/pic-141931372/stock-photo-lotus-flower-in-

thailand.html?src=pp-photo-61336477-vmC5123JqUfb8rxqG8USKw-2 http://www.shutterstock.com/pic-172736525/stock-photo-victoria-regia-the-

largest-water-lily-in-the-world.html?src=vmC5123JqUfb8rxqG8USKw-5-35 Sesuvium sp.- http://dspace.mona.uwi.edu Slide 14: Aloe vera - http://waterconservationwise.com.au/water-efficient-plants

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