Integrated Science M2 Excretion in plants

INTEGRATED SCIENCE

Module 2- Unit 5- Lesson 6 (a)

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http://en.wikipedia.org/wiki/File:The_tree_is_on_fire.jpg

What is excretion?

Waste from respiration and photosynthesis

Some methods of excretion

Other excretory products of plants

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Objectives and Introduction

Objectives

When you complete this slide presentation, you should be able to:•state some examples of waste substances that plants produce.•list some methods of waste excretion used by plants.•state the importance of excretion to plants.

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.

cont’d

What is excretion?




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Introduction

• All organisms produce waste from their metabolic activities carried out for growth, development and generally to sustain life. Excretion serves the purpose of ensuring there is balance in the organism’s body.

• In animals, excretory processes are quite obvious and there are specific organs of excretion. Not so in flowering plants!

• Nevertheless, plants produce and excrete a wide variety of waste, and this is what we’ll explore in this slide presentation.

What is excretion?




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What is Excretion?

WHAT IS EXCRETION?

• It is a characteristic of all living organisms.

• It involves the removal from the organism’s cells and body of waste substances that are formed during cellular metabolic activities, such as respiration and photosynthesis, and which, if left in the body, could be toxic.

WHY CARRY OUT EXCRETION?

• It helps to maintain homeostasis or ‘balance’ of the internal environment.

CHECK MY ANSWER CHECK MY ANSWER

What is excretion?




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What ‘waste’ is produced from respiration in plants?

Every organism carries on respiration in its cells. This equation represents the process of respiration: C6H12O6 + 6O2 6CO2 + 6H2O + Energy

It means that oxygen combines with sugars present in cells to break molecular bonds, thus releasing the energy contained in those bonds. The other products of the respiratory reactions are carbon dioxide and water, which can be excreted if not needed then by the plant for photosynthesis.

What is excretion?




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What ‘waste’ is produced from photosynthesis in plants?

1. From the diagram, write a word and a balanced chemical equation for photo synthesis.

2. What excretory ‘waste’ product results from photosynthesis? Name it and underline it in the equations. Write your answers in your notebook.

Photo: http://www.1ststeps.org/Science/Photosynthesis/photosynthesis.htm

CHECK

http://www.1ststeps.org/Science/Photosynthesis/photosynthesis.htm

What is excretion?




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Feedback to : What ‘waste’ is produced from photosynthesis in plants?

2. O2 is a ‘waste’ product of photosynthesis.

Return now to Body of Lesson 1) in your SIM!

6CO2 + H2 O C6H12O6 + 6O2

light

chlorophyll

1. Carbon dioxide and water react together, in the presence of light, to produce sugar and oxygen.

What is excretion?




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Path of CO2, O2, H2O vapour excretion

http://www.slideshare.net/mazz4/gaseous-exchange-all-17137726

3. What happens to the H2O, O2 and CO2 that form as ‘waste’ from the two processes?

Feedback to 3. These gaseous wastes, e.g. CO2, O2, ethylene and water vapour, diffuse out of the plant via stomata in leaves and also lenticels on tree trunks.Arrows in this and the next diagram show the diffusion pathway.

CHECK MY ANSWER

What is excretion?




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Excretion through stomata1. Gas Excretion and 2. Water vapour loss during transpiration

O2 and CO2 are excreted by diffusion into air

H2O vapour diffuses out during transpiration

Guard cells with stoma open

http://www.worldofteaching.com/powerpoints/biology/plantsgeneral.ppt#262,13

,

cont’d

Watch from 1.01 > http://www.youtube.com/watch?v=ilmgfymbaug

http://www.worldofteaching.com/powerpoints/biology/plantsgeneral.ppt

http://www.youtube.com/watch?v=ilmgfymbaug

What is excretion?




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Excretion O2, CO2 and H2O

• Remember that the centre of trees has only xylem/wood which are dead cells that neither respire nor photosynthesize. Even in the biggest/tallest trees, the living cells found mainly in leaves/outer stem, are in contact with the external air.

• Stomata are present on leaves and soft, green stems, and lenticels are found in areas with bark. The leaves are the organs in which most metabolic activity constantly occur. So, gaseous ‘waste’ easily diffuse out of cells into the intercellular spaces then reach the space just around the stomata.

• Whenever the concentration of the waste gas is higher there than in the immediate air outside the stomata, diffusion occurs into the air, with the ‘waste’ or excretory by-products moving down their concentration gradient.

Return now to Body of Lesson 1) b. ii. in your SIM!•

What is excretion?




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• The waste from respiration and photosynthesis are usually considered as ‘by-products’, rather than waste, as they can be used in either process reciprocally, depending on whether or not light is present.

• Many other metabolic processes occur in flowering plants, and from them, a wide range of wastes are produced. Plants usually store these wastes in certain areas, e.g., leaves, to be later excreted in a variety of ways .

What is excretion?




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•Organic acids: are formed as a by-product of respiration. Organic acids are abundant in leaves and fruits, e.g. citric acid in lemon/lime, tartaric acid in tamarind,

•Resins: are nonvolatile substances probably formed by oxidation of essential oils. Pure resin is hard and brittle, e.g. shellac, lacquer.

•Gums: are formed by decomposition of cellulose of cell walls. Gum arabic and balsam are common examples. Check the next slide!

Source: http://ezinearticles.com/?Excretion-in-Plants&id=7742732

What is excretion?




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Source: http://waynesword.palomar.edu/ecoph13.htm

http://www.visualphotos.com/image/1x7605007/calcium_oxalate_crystals_oil_cells_gossypium

cont’d

Gum oozes out of a branch/stem and is excreted that way

Calcium oxalate crystals and oil stored in cells


http://waynesword.palomar.edu/ecoph13.htm

What is excretion?




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• Essential oils: are volatile oils present in fruits, flowers, e.g., citrus oil, lavender oil.

• Alkaloids: are nitrogenous waste products, e.g., nicotine, caffeine, morphine, cocaine.

• Tannin is a type of bitter waste material used for tanning of leather, for preparing ink etc.

Source: http://ezinearticles.com/?Excretion-in-Plants&id=7742732

Source: http://www.desert-tropicals.com/Articles/Stem_cuttings/Euphorbias.html

• Latex: a sticky, milky-white emulsion of proteins, gum, resins,

e.g., in Poinsettia.

What is excretion?




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Other excretory products of plantsCrystals – chemicals formed in cells.

Left = salt crystals excreted onto Mangrove leaf surface Calcium oxalate crystal inside cell

of Tilia.

http://commons.wikimedia.org/wiki/File:Avicennia_germinans-salt_excretion.jpgTilia sp.: http://waynesword.palomar.edu/ww0601c.htm

http://upload.wikimedia.org/wikipedia/commons/a/a4/Avicennia_germinans-salt_excretion.jpg

What is excretion?




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Methods of excretion in plantsExcretion of gases by diffusion

On woody stems – lenticels are the openings or pores in the layer of bark which is impervious to gases/water.O2 and CO2 can diffuse out through these lenticels, as long as there is a concentration gradient for the waste.

Image source:http://www.tutorvista.com/content/biology/biology-ii/respiration/plants-gaseous-exchange.php

cont’d

What is excretion?




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Methods of excretion in plants

• Salt crystals forming on leaves, similar to that shown on the previous slide for the Black Mangrove, or gum oozing out of a mango tree or a pine tree (‘Christmas tree’) are signs that plants periodically excrete other waste in addition to water vapour, O2 and CO2!

• Flowering plants use a wide range of methods to get rid of the waste that they might have produced and perhaps stored temporarily in leaf, stem cells or other plant parts.

cont’d

What is excretion?




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•Storage: Excretory materials like gum, resin latex, are stored within specialized cells. Sometimes they ooze out on to the surface.

•Shedding of bark: at irregular intervals, trees that have woody trunks, shed their bark in which excretory waste substances are stored.

•Diffusion: Gaseous waste, e.g. CO2, O2, ethylene and water vapour, diffuse through stomata in leaves and also via lenticels.

http://ezinearticles.com/?Excretion-in-Plants&id=7742732 cont’d

http://ezinearticles.com/?Excretion-in-Plants&id=7742732

What is excretion?




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Methods of excretion in plantsGuttation

Guttation: water droplets passed out of special pores at leaf margins. Water may contain sugars/salts to be excreted.

http://en.wikipedia.org/wiki/Guttation

cont’d

http://www.rosenfreundehannover.de/botanik.php

What is excretion?




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• Leaf fall: Deciduous plants like tobacco, tea, almond, get rid of excretory waste, stored within leaves, through leaf fall.

• Waste compounds are often stored in dead heartwood, bark and leaves which die/fall off.

• When chlorophyll breaks down, other compounds in leaves give the characteristic autumn colours seen just before leaf fall.

http://www.na.fs.fed.us/spfo/pubs/misc/leaves/leaves.htm http://ezinearticles.com/?Excretion-in-Plants&id=7742732

cont’d

What is excretion?




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• Fruit and flower fall: Waste stored within flower petals, sepals, bracts, also seeds and fruit walls are eliminated when these fall off.

• Leaching: is a process of diffusion of water, soluble substances like salts, hormones, inhibitors etc. from underground parts of plants body into the soil."

Return to Body of Lesson 3) b. in your SIM.

http://ezinearticles.com/?Excretion-in-Plants&id=7742732

What is excretion?




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Summary

• Excretion is the removal from the organism’s body of waste substances produced during cellular metabolism.

• Plants do not have any set excretory system, so, getting rid of wastes often involves storing the substance (e.g. calcium oxalate, tannins) in some plant tissue, passing it out onto leaf surfaces (e.g. salts) or diffusion (e.g. O2, CO2).

• Because salts are so removed, excretion also serves the important function of osmo-regulation which maintains homeostasis.

• Go through the summary comparison on the next slide.

What is excretion?




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Type of Organism

Structure/s Excretorywaste

Process/esinvolved

Plants Stomata, lenticels

H2O, CO2,

H2O vapour

Diffusion

Evapo-Transpiration

Vacuoles in Cells of leaves

Insoluble crystalsOils, gums, tannins etc.

Stored in plant cells;Eliminated when

leaf etc. dies

HumansNephrons in the kidneys

H2O, urea, salts, ammonia, uric acid,

various drugs

UltrafiltrationReabsorption

SecretionExcretion

What is excretion?




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End of Activity

• You have reached the end of the activities. • If you wish to review any concepts in this lesson, go

to the first slide and click the subtopic on the left.• If you have finished viewing the lesson, click the

Close (X) button.

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What is excretion?




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CREDITS

• http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookplantanat.html• http://en.wikipedia.org/wiki/Autumn_leaf_color • http://life.bio.sunysb.edu/marinebio/mg_06.jpg• http://www.1ststeps.org/Science/Photosynthesis/photosynthesis.htm• http://ezinearticles.com/?Excretion-in-Plants&id=7742732• http://waynesword.palomar.edu/ecoph13.htm• http://www.desert-tropicals.com/Articles/Stem_cuttings/Euphorbias.html• http://commons.wikimedia.org/wiki/File:Avicennia_germinans-salt_excretion.jpg• http://waynesword.palomar.edu/ww0601c.htm• http://www.slideshare.net/mazz4/gaseous-exchange-all-17137726• http://www.worldofteaching.com/powerpoints/biology/plantsgeneral.ppt#262,13,• http://tinyurl.com/7gen23d • http://www.tutorvista.com/content/biology/biology-ii/respiration/plants-gaseous-

exchange.php• http://www.rosenfreundehannover.de/botanik.php• http://en.wikipedia.org/wiki/Guttation• http://www.na.fs.fed.us/spfo/pubs/misc/leaves/leaves.htm • http://humanphysiology2011.wikispaces.com/file/view/17.21.jpg/224354606/800x282/17.21.jpg

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Integrated Science M2 Excretion in plants