Plants and Photosynthesis

Plants  Plants are made up of different parts.  There are many different kinds of plants:  Angiosperms have flowers.  Mosses and liverworts don’t have a classic plant structure.  Cacti don’t have leaves.

Plants cont’d  Basic similarity is that plants produce their own energy.  Vascular plants are a very common plant type. They have the following structures:  Roots  Stems/shoots  Leaves

Plants cont’d  Have a go at drawing this plant in your book. Make sure you label it too. Make sure you label the 3 basic parts.

Plant parts Write down these notes in your books.  Roots: are for soaking up water and minerals from the ground. They also anchor the plant.  Stems/shoots: are support structures that transport food and water.  Xylem: tubes that transport water and minerals upwards.  Phloem: tubes that transport sugars downwards.  Leaves: are the part that does photosynthesis/makes energy.

Plants  I will give you a copy of the plant picture to glue into your books.  Glue it in next to or near the picture that you drew of the plant.

Leaves and photosynthesis  We are now going to learn about leaves and photosynthesis.  Leaves make energy via photosynthesis.  What do plants do? They grow.  What do we as humans need to make us grow? Food/energy.

Leaves and photosynthesis  Now the question is how do plants grow?  They need energy too. But plants can produce their energy.  Plants use light to convert water and carbon dioxide into energy/plant material/growth.  This process is called photosynthesis.

Photosynthesis  Carbon dioxide + water + light  glucose and oxygen  6CO2 + 6H2O + light and chlorophyll  C6H12O6 + 6O2  What is glucose? It’s a type of sugar. Somewhere in the leaf this process is happening. The part of the leaf that is responsible for this is the chloroplast (the part we see as green in the leaf).

Photosynthesis A stomata  Photosynthesis takes place in the chloroplast of a cell because of a pigment called chlorophyll which traps the light.  Like I mentioned earlier the xylem transports the water to the leaf.  But where does the plant get the CO2 from? From the air, through a pore in the underside of a leaf called a stomata. Also the oxygen is released through this same pore/stomata.

Photosynthesis  A plant gets CO2 from the air through a pore known as a stomata. Plants release oxygen through stomata.  Now photosynthesis is more complex than the equation looks, because there are also enzymes involved to make the reaction occur.  Basically there is one part of the reaction that requires light energy to transform into chemical energy (ATP), and that is called the light reaction, and then there is a second part where enzyme reactions cause carbon dioxide and hydrogen ions to combine to form glucose, and this part is the dark reaction.

Photosynthesis  Light reaction: light energy  chemical energy  ATP and NADPH  Dark reaction: carbon dioxide and energy  glucose  This is also known as the Calvin Cycle.

Photosynthesis overview.png

Videos  We are now going to look at a couple of videos about photosynthesis.  So go back to your wiki page and follow the link to the videos.

References  Phillips, G et al, 2004, Sci3, Pearson Education Australia, Sydney. 