Biology

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

Since plant species evolved for survival in different environments, their internal solute concentrations should be different from their marine ancestors. Which hypothesis do you think is more likely to be true? PART III: DESIGN YOUR OWN EXPERIMENT Do plants living in a freshwater pond have the same solute concentrations inside their cells as plants living

Red blood cells will burst if placed in distilled water (0% salt). Why didn’t the onion cells burst? The number of plasmolyzed and unplasmolyzed onion cells in different concentrations of salt solution. Salt concentration Number of cells plasmolyzed Number of cells counted Percent of cells plasmolyzed 0% 1% 2% 3% 4% 5% 6% 7% 8%

Using the plasmolysis threshold to estimate the concentration of solutes and water inside living cells Under your compound microscope, the cell membrane of a turgid cell is invisible because it is pressed up against the inner surface of the cell wall. But in a plasmolyzed cell, the cell membrane is visible because it has pulled

  PART II: WATER CONTENT OF CELLS Although living tissue is about 75-85% water, the effective concentration of solutes inside cells is not 15- 25%. Most of the non-water components of cells are bound into cell structures and are not in solution, so do not influence osmotic pressure. It is the concentration of solutes (substances

why does the fluid level in the osmometer rise, at least at first? Analysis and Discussion 1. In terms of water molecules and solute concentration gradients, why does the fluid level in the osmometer rise, at least at first? (Hint: Think about the concentration gradient and the net movement of water at the molecular level.)