Connecting Concepts
Use Science Graphics
A scientist studied the effect of exposing DNA to various wavelengths of ultraviolet light. The scientist determined the number of copying errors made after exposure to ultraviolet rays. The graph shows the results. Use the graph to answer questions 27 and 28.
Interpret Graphs The most damaging effects of ultraviolet light on DNA replication occur at which wavelength?
Infer What conclusion would you draw from the graph about the effect of ultraviolet light on living organisms?
Pose Questions Ozone is a molecule that is very effective at absorbing ultraviolet light from the sun. Evidence indicates that human activities have contributed to the destruction of ozone in the atmosphere. What question would you ask about the effect of removing ozone from the atmosphere?
Write About Science
Explanation Recall that Gregor Mendel concluded that factors, which we now call genes, determine the traits that pass from one generation to the next. Imagine that you could send a letter backward in time to Mendel. Write a letter to him in which you explain what a gene consists of in molecular terms.
Assess the
In their original paper describing the structure of DNA, Watson and Crick noted in a famous sentence that the structure they were proposing immediately suggested how DNA could make a copy of itself. Explain what Watson and Crick meant when they said this.
Analyzing Data
The following table shows the results of measuring the percentages of the four bases in the DNA of several different organisms. Some of the values are missing from the table.
Predict Based on Chargaff's rule, the percentage of adenine bases in human DNA should be around
30.9%.
19.9%.
21.5%.
13.4%.
Calculate The value for the percent of guanine bases in the bacterium would be expected to be about
13.4%.
28.8%.
36.6%.
There is not enough information given.
Predict If the two DNA strands of the bacterium were separated and the base composition of just one of the strands was determined, you could expect
the amount of A to equal the amount of T.
the amount of C to equal the amount of G.
the amount of A to equal the amounts of T, C, and G.
the four nitrogenous bases to have any value.
Table of Contents
- Formulas and Equations
- Applying Formulas and Equations
- Mean, Median, and Mode
- Estimation
- Using Measurements in Calculations
- Effects of Measurement Errors
- Accuracy
- Precision
- Comparing Accuracy and Precision
- Significant Figures
- Calculating With Significant Figures
- Scientific Notation
- Calculating With Scientific Notation
- Dimensional Analysis
- Applying Dimensional Analysis