Download Photosynthesis: The Process of Converting Light Energy into Chemical Energy and more Study notes Biology in PDF only on Docsity! Exercise 4: Photosynthesis: Using Light to Make Food Section A: Photosynthesis – Overview Plants are autotrophs/producers Photosynthesis converts light energy into chemical energy to form glucose Overall reaction: 6CO2 + 6 H2O + Light energy ---> C6H12O6 + 6O2 Carbon dioxide + Water + Light energy ---> Glucose + Oxygen The oxygen is formed by the break down of H2O molecules, and it is formed as a byproduct Photosynthesis occurs in the chloroplasts and is involved in two reactions: o Light reaction, capturing energy from the sunlight and using it to make ATP & NADH (molecules that can store energy), it occurs in the thylakoids and granna o Dark reaction (Calvin Cycle), use CO2 & ATP to make organic molecules (such as glucose); it occurs in the stroma of the chloroplast. Section B: Leaves and Chloroplasts are Adaptations for Photosynthesis Epidermis: upper & lower; secrets cuticles that forms a waxy layer to prevent water loss Stoma (stomata, pl.): pore/opening; controls gas exchange & evaporation of H2O Mesophyll: between the upper and lower epidermis; a multi-layer tissue Vascular bundles: functions in transporting water, minerals, and products of photosynthesis Palisade mesophyll (also called Palisade parenchyma): major site for photosynthesis; also carries out gas exchange function Spongy mesophyll (also called Spongy parenchyma): major site for gas exchange; also carries out photosynthesis Chloroplasts: photosynthesis occurs within the thylakoids & granna; CO2 fixation occurs in the stroma Section C: Visible Light Drives the Light Reaction Light reaction: 12H2O ---> 6O2 + 24H+ + 24e- Light is an example of electromagnetic radiation, energy that transmitted as discrete particles called photons The visible light spectrum is the energy of certain wavelengths that produces light visible by human eyes The longer the wavelength, the lower the energy; on the other hand, the shorter the wavelength, the higher the energy Section D: Photosystems Capture Solar Energy Photon Section E: Photosynthetic Pigments Three basic types of plant pigments: o Chlorophyll o Carotenoids o Phycocyanins Different types of plant pigments absorb light at different wavelength, which can increase the energy capture efficiency of the plant Know the light each pigment absorbs and the color it reflects Chromatography o Paper chromatography – technique used to separate the various components of a liquid mixture o Utilizes the different affinities of the individual components in the liquid mixture to the chromatography paper (stationary phase) and their different rate of solubility in the solvent (moving phase) o Ex. molecules that have high affinity with the chromatography paper will migrate slower than molecules that have low affinity with the chromatography paper Atom at it’s ground state (stable state/stable energy level); the electrons are at the ground orbit As the photon hits the atom, an electron is being bumped into the next energy level/orbit. The electron gains potential energy but is very unstable As the electron moves back down to the ground state, the potential energy is lost in the form of heat and light. In theory, if all the energy has been converted to light, then the light emitted (you observed) will have high energy. However, only a portion of the total energy is being converted to light, so the light emitted has a lower energy. Heat and Light
