Gabriela Rios-Martinez
March 1, 2014
BIO 141
Exam 1 Study Questions

Chapter 1: Biology and the Tree of Life (#1 – 4)

1. What is the difference between a hypothesis and a scientific Theory? Between a hypothesis and a prediction? What kinds of hypotheses are useful for scientific investigations that try to explain the natural world, and which are not? Give one or more examples of hypotheses that are and are not scientifically useful. (a.) A scientific theory has two components; a pattern, and a process that creates the pattern. A hypothesis is a testable statement that explains a phenomenon of a set of observations.
(b.) A prediction is different from both because it describes a result of a hypothesis that must be correct …show more content…

They are ampipathic.

6. In the absence of specific carrier proteins, which of the following can diffuse readily across the plasma membrane of a cell? (a.) Small nonpolar molecules move across bilayers quickly. In contrast, large molecules and charged substances cross the membrane slowly, if at all. Nonpolar and small polar molecules can pass through the cell membrane, so they diffuse across it in response to concentration gradients. Carbon dioxide and oxygen are two molecules that undergo this simple diffusion through the membrane.

7. Using artificial liposomes researchers showed that phospholipid bilayer membranes containing different amounts of cholesterol have different permeability to glycerol. What was the observed relationship between cholesterol content and glycerol permeability? How can the effect of cholesterol be explained? What other experimental variable used in these experiments affected membrane permeability (and membrane fluidity) in a consistent way? What was the effect observed in this case and what is a reasonable explanation for the observed effect?

(a.) Adding cholesterol to membranes decreases their permeability to glycerol.
(b.) Cholesterol reduces permeability because it fills spaces in phospholipid bilayers.
(c.) Temperature was also