IBDP Biology Chapter 8 Notes

metabolism, cell respiration and photosynthesis


These notes have specially been curated by expert teachers to simplify and enlighten concepts given in IB Biology HL. The notes are comprehensive in nature and are sufficient to study the chapter in depth and one need not look for other resources beyond the notes provided on our website which can be accessed for free. The notes for Cell Biology IBDP HL are available on our official website and can be downloaded for free. You are one click away from obtaining all that you need to score well in IB Biology HL.

The material made available on Tychr’s website is available for all IBDP subjects and is specially curated after an extensive amount of effort to ensure that the notes are in consonance with the IB curriculum and are an amalgamation from various textbooks prescribed by the IBO.Students often face a challenge understanding concepts, especially concepts that are new and tricky. These IB Biology Notes will help the student cover the chapter of Cell Biology entirely while explaining each and every concept in a detailed and easy way.

In this chapter, we are going to deal with cell respiration and photosynthesis in green plants. Metabolic reactions are mediated by enzymes that form an enzyme-substrate complex at the active site. This process can be inhibited competitively (by competing for the active site, e.g. sulpha drugs) or non competitively (by modifying the structure of the active site, aka allosteric inhibition). Another kind of inhibition in which the end product itself inhibits the enzyme called end-product inhibition.

Cell respiration is a catabolic redox process in which glucose is oxidised to release energy. It starts with glycolysis, an anaerobic process in which glucose (6 C) is oxidised to pyruvate( 3 C) with a net gain of 2 ATP followed by a link reaction which converts pyruvate to Acetyl-CoA (2 C). Acetyl-CoA then enters the Krebs cycle. Throughout all three steps NADH and FADH2 are produced, which undergo oxidative phosphorylation via the ETC. Oxidative phosphorylation occurs in the inner mitochondrial membrane and yields ATP with the help of ATP Synthase( NADH 3 ATP; FADH2 2 ATP).

Alternatively, we also discuss photosynthesis process by which green plants convert light energy into chemical energy. It occurs in chloroplasts and utilises the light energy to reduce the atmospheric CO2 to glucose. It has two reactions: light-dependent (site: thylakoids) and light-independent(aka Calvin cycle site:stroma). Plants absorb light energy with the help of photosystems present in thylakoids.