Topics: Osmosis, Diffusion, Membrane biology Pages: 3 (1141 words) Published: March 6, 2015
Biology 120
Lab Report 1

Name: Samantha Sweeney

Use complete sentences to type your answers to the following questions, or type your answers into the table. You may type them in this word document, then print it out and bring it to lab. Remember, no handwriting is permitted. Do NOT copy information from a textbook, journals, fellow students, or the Internet! Paraphrased material must include correct citations.

1. A. Explain the differences between passive and active transport across cell membranes. Passive transport means that there is no energy required in the process of membrane transport (Diffusion, Osmosis, & Facilitated Diffusion). Concentration gradients are also used in passive transport. Active transport requires cellular energy (ATP) to carry out the process of membrane transport. Substances are moved through an impermeable membrane or against their concentration gradient, which requires force, making the need for energy.

B. For the following, indicate whether the method is passive or active:

Active Transport ACTIVEFiltrationPASSIVE

DiffusionPASSIVEFacilitated DiffusionPASSIVE

EndocytosisACTIVESecondary Active TransportACTIVE


C. Explain why substances need to cross the cell membrane. Substances need to cross the cell membrane in order to maintain homeostasis and function normally. For example, nutrients need to go into the cell and waste materials must come out.

2. A. Explain the term “concentration gradient”. Make sure to discuss the difference between a solution's concentration and a concentration gradient. A concentration gradient is based off of an unequal distribution of molecules across the cell membrane. A solution’s concentration as compared to another solution’s concentration gives us the concentration gradient.

B. An artificial cell contains 0.03 M sucrose and 0.02 M glucose. It is placed into a solution...
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