Plant Science

After finishing our quite extensive foray into leaf structure, function, and modifications, we finally start to look at what is arguably the main purpose of leaves: absorbing light energy, and using that energy to fix carbon dioxide.

In this lecture we will discuss the discovery of photosynthesis, and the general principle of the process.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

After finishing our quite extensive foray into leaf structure, function, and modifications, we finally start to look at what is arguably the main purpose of leaves: absorbing light energy, and using that energy to fix carbon dioxide.

In this lecture we will discuss the discovery of photosynthesis, and the general principle of the process.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

After finishing our quite extensive foray into leaf structure, function, and modifications, we finally start to look at what is arguably the main purpose of leaves: absorbing light energy, and using that energy to fix carbon dioxide.

In this lecture we will discuss the discovery of photosynthesis, and the general principle of the process.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Leaves have features that prevent uncontrolled water loss such as cuticles and wax layers. Because these impermeable layers also prevent diffusion of carbondioxide into the leaf air space plants have developed structures that act like valves and control the flow of water vapour and carbondioxide: stomata.

The central opening, called pore or aperture, is surrounded by two guard cells that contain chloroplasts. The guard cells can swell (increase in turgor) and shrink (decrease in turgor), thereby regulating the size of the stomatal aperture. In this lecture we have a look at the principles that determine the pore size, and the mechanics behind it.

Leaves have features that prevent uncontrolled water loss such as cuticles and wax layers. Because these impermeable layers also prevent diffusion of carbondioxide into the leaf air space plants have developed structures that act like valves and control the flow of water vapour and carbondioxide: stomata.

The central opening, called pore or aperture, is surrounded by two guard cells that contain chloroplasts. The guard cells can swell (increase in turgor) and shrink (decrease in turgor), thereby regulating the size of the stomatal aperture. In this lecture we have a look at the principles that determine the pore size, and the mechanics behind it.

Leaves are the main "organs" of plants responsible for capturing light energy, and converting it through fixation of carbon dioxide into chemical energy in the form of sugars.

In this lecture we look at modified leaves that serve as adaptations to lack or excess of water, lack of nutrients, and as protective structures to prevent herbivory. We also take a look at the structural organisation of a "typical" leaf.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Leaves are the main "organs" of plants responsible for capturing light energy, and converting it through fixation of carbon dioxide into chemical energy in the form of sugars.

In this lecture we look at modified leaves that serve as adaptations to lack or excess of water, lack of nutrients, and as protective structures to prevent herbivory. We also take a look at the structural organisation of a "typical" leaf.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Leaves are the main "organs" of plants responsible for capturing light energy, and converting it through fixation of carbon dioxide into chemical energy in the form of sugars.

In this lecture we look at modified leaves that serve as adaptations to lack or excess of water, lack of nutrients, and as protective structures to prevent herbivory. We also take a look at the structural organisation of a "typical" leaf.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Leaves are the main "organs" of plants responsible for capturing light energy, and converting it through fixation of carbon dioxide into chemical energy in the form of sugars.

In this lecture we look at modified leaves that serve as adaptations to lack or excess of water, lack of nutrients, and as protective structures to prevent herbivory. We also take a look at the structural organisation of a "typical" leaf.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

The third and final lecture on plant hormones is about brewing beer and Prince. No, of course not, but both are used as examples for the effects of gibberellins and abscisic acid.

Gibberellins were first discovered in "foolish rice" (or banana) where a fungal infection results in increased levels of gibberellins and very long, extended internodes. They are a large group of compounds (more than 120 gibberellins are known) and also stimulate seed germination, an effect that is taken advantage of in the malting process. Plants with lower amounts of gibberellins are referred to as "dwarf" mutants and have played an important role in the agricultural revolution.

Despite its name, abscisic acid is generally not involved (with a small number of exceptions) in leaf abscission. Instead, it plays a major role in all plant stress-related processes. Most importantly, closure of stomata as a result of waterstress is caused by abscisic acid. Another important role of absisic acid is the delay of seed germination - together with gibberellins this results in a very tight regulation.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.