1. You are a writer for "Consumer Reports" magazine and you are asked to design an experiment to evaluate the effectiveness of three brands of whitening strips for teeth. Describe how you would do this using the scientific method. Include all of the steps, control group, experimental groups, and variables.

2. Your biology class is performing an osmosis experiment. You are given three identical stalks of celery and three salt solutions of varying solute amounts. The data table below compares the solute amount of the celery stalks to the solutions.

Solute Amount of the SolutionWater Amount of the Solution

Solution A less than the celery stalkmore water than the celery stalk
Solution B same as the celery stalksame water as the celery stalk
Solution C more than the celery stalk less water than the celery stalk

a). Identify which solution is isotonic, hypertonic, or hypotonic to the celery stalk cells
b). Describe what happens when the celery stalk is placed into each of the respective solution.

3. Dihybrid cross. The kernels (seeds) on an ear of corn are all offspring of one set of parents. There are 2 pairs of alleles on separate homologous chromosomes (purple or yellow kernels on one pair, plump or shrunken kernels on another). Yellow (Y) is dominant to purple (y) and plump (P) is dominant to shrunken (p). If the genotype of parent plants are YyPp and yyPp, what are the expected probabilities of the genotypes and phenotypes of the offspring kernels? Explain your reasoning.

4. A population of grasshoppers in the Kansas prairie has two color phenotypes, with 90% of the grasshoppers green and 10% brown. Typically in the last century, the prairie receives adequate rain to maintain healthy green grass, but for the last decade the prairie suffers a severe drought and is also invaded by a bird that eats grasshoppers.

Briefly explain in terms of the four parts of natural selection listed below how the population of grasshoppers would be expected to change during the drought years.

overproduction -

variation -

competition& survival -

differential reproduction -

5. Describe an environmental problem that you feel is the most urgent worldwide. Which areas of the world are suffering the most from the problem? Propose a solution to the problem.

6. Describe three structures found in plant cells but not animal cells. Describe the function of each structure, and how each benefits plant cells but is not necessary for animal cells.

7. Explain why top carnivores, such as eagles and tigers, have low population densities in nature. Include processes of the energy pyramid (trophic levels) in your answer.\