Plant Pigments and Photosynthesis 1. What is the color of the following plant pigments? Which wavelengths do they absorb?
Pigment Color Wavelengths (colors) absorbed
Chlorophyll A
Chlorophyll B
Carotene
Xanthophyll
Anthocyanin
2. Explain how the wavelengths absorbed and reflected determine the color of a pigment?
3. Take a look at the overall reaction for photosynthesis and suggest two ways that the rate of photosynthesis could be measured (Hint: Consider how the substrates and products will change throughout the course of the reaction).
6CO2 + 6H2O + Light Energ → C6H12O6 + 6O2
4. Many deciduous trees have leaves that turn yellow in the fall. What is happening in the leaves at the cellular and molecular level that is responsible for this color change?
5. Chloroplasts are the organelles in plant cells that convert solar energy to chemical energy (sugars) that can be used by the cell. Mitochondria are organelles in all eukaryotic cells that convert sugars to ATP Both organelles are have double membranes and contain their own set of DNA. What is the likely explanation for this?

1. Chlorophyll A has a yellow-green pigment and absorbs at a wavelength of 430-662 nm.  Chlorophyll B has a blue-green pigment and absorbs at a wavelength of 453-642 nm. Carotene has an orange pigment and absorbs at a wavelength of 460-550 nm. Xanthophyll has a yellow pigment and absorbs at a wavelength of 700 nm. Anthocyanin has a purple pigment and absorbs at a wavelength of 660 nm.

2. Plant and planktons that survive by photosynthesis do so with the help of pigments. These pigments help them trap light ( e.g sunlight). When this happens a reflection occurs which gives rise to the pigment colour observed which is usually not absorbed. A typical example is seen in chlorophyll which is green pigmented hence it absorbs all other wavelengths of light the except green.

3. The various ways in which the rate of photosynthesis can be measured include: Measuring the amount of carbon(IV)oxide uptake as well as measuring the amount of oxygen produced.

The reason for the colour change in deciduous trees in the fall is because the chlorophyll in the leaves of the plants is broken down leading to the loss of the green colouration. Also, the presence of anthocyanin can also be responsible for the yellow pigmentation.

5. Due to the evolution of species, and the fact that life originated from microbes, microbes have evolved from the single membrane to more complex systems with specialized organs like the mitochondria and chloroplasts. Early microbes were photosynthetic in nature e.g phytoplanktons which have evolved specialized systems controlled by the DNA to ensure their survival.

Explanation:

1. Chlorophyll A has a yellow-green pigment and absorbs at a wavelength of 430-662 nm.  Chlorophyll B has a blue-green pigment and absorbs at a wavelength of 453-642 nm. Carotene has an orange pigment and absorbs at a wavelength of 460-550 nm. Xanthophyll has a yellow pigment and absorbs at a wavelength of 700 nm. Anthocyanin has a purple pigment and absorbs at a wavelength of 660 nm.

2. Plant and planktons that survive by photosynthesis do so with the help of pigments. These pigments help them trap light ( e.g sunlight). When this happens a reflection occurs which gives rise to the pigment colour observed which is usually not absorbed. A typical example is seen in chlorophyll which is green pigmented hence it absorbs all other wavelengths of light the except green.

3. The various ways in which the rate of photosynthesis can be measured include: Measuring the amount of carbon(IV)oxide uptake as well as measuring the amount of oxygen produced.

The reason for the colour change in deciduous trees in the fall is because the chlorophyll in the leaves of the plants is broken down leading to the loss of the green colouration. Also, the presence of anthocyanin can also be responsible for the yellow pigmentation.

5. Due to the evolution of species, and the fact that life originated from microbes, microbes have evolved from the single membrane to more complex systems with specialized organs like the mitochondria and chloroplasts. Early microbes were photosynthetic in nature e.g phytoplanktons which have evolved specialized systems controlled by the DNA to ensure their survival.

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