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PART I: DNA FINGERPRINTING DNA fingerprinting has many applications. It is now routinely used to test samples of blood, hair, saliva and semen left at crime scenes. The results are compared to those of a suspect to establish the individual’s guilt. DNA fingerprinting can also be used to establish familial relationships in paternity cases, to […]

Exercise 5 – The effect of the color of light on the rate of photosynthesis Green leaves look green not because they absorb green light, but because they reflect green light to our eyes. A pigment’s absorption spectrum (Figure 3) quantifies graphically how much of each color (wavelength) the pigment absorbs. Chlorophyll a and chlorophyll

Exercise 4 – The effect of carbon dioxide and pH on the rate of photosynthesis 1. Use a cork borer to cut 100 or more leaf disks from a spinach leaf (spinach is rich in chloroplasts). Cut to either side of the largest leaf veins, not through them. Discard any disks that are bruised or

PART III: FACTORS AFFECTING THE RATE OF PHOTOSYNTHESIS In this section you and you partner(s) will do experiments to test the influence of two environmental factors on the rate of photosynthesis. Possible factors affecting photosynthetic rate Your experience with enzyme-catalyzed reactions from minicourse 2 suggest a number of factors that might influence the rate of

PART II: STRUCTURAL ORGANIZATION OF LEAVES 9.2 Exercise 2 – Internal features of a leaf All the structures of the leaf can be understood in terms of their role in maximizing the efficiency with which the chloroplasts carry out photosynthesis in different habitats. As you study the structures below, ask yourself, “How does this structure

How many different pigments (spots) were present in your leaf? Analysis and Discussion 1. How many different pigments (spots) were present — in your leaf? — in the leaf of the other species? 2. What causes the differences in color? 3. The two spots closest to the source point are usually “chlorophyll a” (bluish green)

Exercise 1 – Separation of leaf pigments by paper chromatography Chromatography is a technique used to separate substances in a mixture. It can be used to determine what pigments are present in a leaf. Paper chromatography can separate different pigments only if those pigments (a) have different solubilities, and/or (b) differ in the degree to

PART I: LIGHT-ABSORBING PIGMENTS Sunlight is “white” light composed of all the wavelengths (colors) of the visible spectrum: red-orange- yellow-green-blue-indigo-violet (or “Roy G. Biv.”). Photosynthesis begins with the absorption of sunlight by pigments in the chloroplasts. These pigments absorb some colors of light better than others. For example, a green leaf contains the pigment chlorophyll.

Explain how paper chromatography is used to separate the light-absorbing pigments in a leaf. Prepare and interpret a chromatogram. Lab 4 – Photosynthesis 9 Almost all life on earth depends directly or indirectly on photosynthesis: the ability of certain organisms (notably green plants) to capture and store the energy of sunlight. Photosynthesis in green plants

What advantages and/or disadvantages might this have for freshwater plants? Analysis and Discussion For cells to survive in environments whose salinity is much lower or much higher than 3%, the cells may need to pump salt in (or out) to maintain a suitable internal environment. However, molecular pumps require a lot of energy (ATP), so