All organisms require energy to perform cellular processes. Although different organisms obtain energy in different ways, they often use it in similar ways.  Plants use the pigment chlorophyll to absorb light energy in chloroplasts in their leaves and transform it into usable chemical energy via the process of photosynthesis. Photosynthesis is an endergonic reaction, meaning it requires an input of energy to occur. The energy for photosynthesis is obtained from light.

While it appears a simple process, it is actually quite complex and involves several steps. Two types of reactions occur in photosynthesis: light dependent (photochemical) and light independent (biochemical) reactions.

Light dependent reactions are known as photochemical reactions because they require light to occur.  Light independent reactions are known as biochemical reactions because they occur independently of light conditions.

Photochemical reactions oxidise water (split the hydrogen and oxygen atoms), release the oxygen as a bi-product, produce ATP (adenosine triphosphate) and reduce NADP to become NADPH (nicotinamide adenine dinucleotide phosphate-oxidase). The ATP and NADPH are then used in biochemical reactions which reduce CO2 to carbohydrates in the form of sugar.

Biochemical reactions of photosynthesis occur either in the light or in the dark, provided that ATP, NADPH and CO2 are all present. NADPH is a membrane bound enzyme complex which is formed from NADP in the last step of the electron chain in the light dependent reactions of photosynthesis.

A knowledge of the processes of photosynthesis and respiration is preferred.

In this program students will:

• Investigate photosynthetic rate in chloroplasts under different light conditions.
• Practise using scientific investigation methodologies to design their own experiment.
• Explain leaf gas exchange after altering different variables.

Students will:

• Measure the rate of photosynthesis occurring in chloroplasts in light and dark conditions.
• Design and conduct an experiment measuring leaf gas exchange and rate of photosynthesis.

Ecolinc Learn Online is a virtual outreach learning management system (LMS) offering interactive online courses for students and teachers. These courses can be undertaken either as a pre-visit, post-visit or stand-alone.

Students are encouraged to do the pre-learning course on Ecolinc Learn Online called Photosynthesis in C3, C4 and CAM Plants prior to coming to Ecolinc. In this course students will become familiar with the inputs, outputs and locations of the light dependent and light independent stages of photosynthesis in C3 plants, explore the electron transport chain and Calvin cycle, compare C3, C4 and CAM plants, analyse CRISPR cas9 and see how it may be used to improve the efficiency of photosynthesis and our crops.

Area of Study 2: How are biochemical pathways regulated?

Regulation of biochemical pathways in photosynthesis and cellular respiration

• The general structure of the biochemical pathways in photosynthesis and cellular respiration from initial reactant to final product

Photosynthesis as an example of biochemical pathways

• Inputs, outputs and locations of the light dependent and light independent stages of photosynthesis in C3 plants
• The factors that affect the rate of photosynthesis: light availability, water availability, temperature and carbon dioxide concentration