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This website provides information on plant structure and support.

This diagram shows the process of secondary thickening in stems

This diagrams shows the annual rings of a tree trunk

Investigation - tree rings and climate change

Every year a tree forms a new layer of xylem around the trunk. This forms tree rings, which are visible as circles in a cross section of a tree that has beencut down. Each tree ring, or wood layer, consists of two colours of wood; light wood that grows in spring and summer and dark wood that grows in autumn andwinter. Tree rings can be counted to give you a rough estimation of the age of a tree. Occasionally a tree will form many rings in one year or miss formingrings in a year. The width of tree rings is greater in years where good growing conditions occur. In years with droughts or low temperatures, the trees willproduce smaller rings. Therefore, by looking at the tree rings you can get an idea of the weather affecting a tree in a particular year. Scientists can usethis information to help determine the weather patterns of the past as well as events such as forest fires, earthquakes and volcanic eruptions. The study ofpast events using the growth rings of trees is known as dendrochronology (“dendros” = tree, “chronos” = time).

Aim: to observe annual tree rings to assess age and climatic conditions

1. Find a cut or fallen tree, and count the tree rings, starting with the innermost ring. Measure the width of each ring using a ruler, or make a note ofwhether a ring is narrow or wide. Make a note of any scars caused by events such as fires or pests.

2. Draw a bar graph showing the width of your tree rings for every year of the tree's life.

3. How old is your tree? What can you say about the climatic conditions throughout the life of your tree?

http://www.classzone.com/books/earth_science/terc/content/investigations/es2905/ es2905page01.cfm

This is a link to an online tutorial about counting tree rings.


This is a link to a great cartoon video about the different tissue layers in trees (xylem, phloem, etc) and the formation of tree rings.


This is a link to a good website about tissue layers in trees.

Economic importance of plant support tissues

Plant support tissue supplies with two important resources namely wood and fibre . Xylem is a source of wood and the sclerenchyma is a source of fibre.

Of course in order to obtain wood and fibre we need to cut down numerous trees. This is called deforestation . Deforestation has escalated in the recent years due to the growing need for wood.


Collect data showing the area covered by forests in the years 1990 and 2010. Find this data for the following countries: South Africa, Europe, Asia, Northand Central America and South America.

Divide the class into two teams. One group will argue the need for us to cut down trees and the other will be responsible for convincing us thatdeforestation must be reduced dramatically.

Indigenous knowledge

Making paper, flax, cotton, sisal. Traditional use of fibrous plants by san bushman using sansevaria to make rope etc. thatching. Can we please get helpwith this?

Dicotyledonous leaf

Internal structure of the dicotyledonous leaf

Refer to chapter 1 to remind yourselves of the internal structure of a dicotyledonous leaf.

This diagram shows the movement of water through a dicot leaf.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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why and for what was five kingdom of classification of organisms introduced
give the ans as fast as possible
Comment on the ozone depletion over the period of 1982 to 1996
Mpho Reply

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Source:  OpenStax, Siyavula: life sciences grade 10. OpenStax CNX. Apr 11, 2012 Download for free at http://cnx.org/content/col11410/1.3
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