Think Critically
Infer Would you expect skin cells to contain more or fewer mitochondria than muscle cells? Explain your answer.
Infer Pacemakers are devices that help keep heart muscle cells contracting at a steady rate. If a person needs a pacemaker, what does that suggest about his or her heart cells' ability to send and receive chemical messages?
Connecting Concepts
Use Science Graphics
Use the data table to answer questions 29–31.
Classify Classify each of the cells listed as prokaryotic or eukaryotic.
Compare and Contrast Compare the sizes of the prokaryotic cells and eukaryotic cells.
Infer Chlamydomonas reinhardtii is a single-celled organism with an approximate diameter of 10 µm. Is it more likely a prokaryotic or eukaryotic organism? Explain your answer.
Write About Science
Persuasion Different beverages have different concentrations of solutes. Some beverages have low solute concentrations and can be a source of water for body cells. Other beverages have high solute concentrations and can actually dehydrate your body cells. Should companies that market high-solute drinks say that the drinks quench thirst?
33. Assess the
What is the relationship between active transport and homeostasis? Give one example of active transport in an organism, and explain how the organism uses energy to maintain homeostasis.
Analyzing Data
Most materials entering the cell pass across the cell membrane by diffusion. In general, the larger the molecule, the slower the molecule diffuses across the membrane. The graph shows the sizes of several molecules that can diffuse across a lipid bilayer.
Calculate By approximately what percentage is a molecule of carbon dioxide smaller than a molecule of glucose?
25%
50%
75%
100%
Formulate Hypotheses Which of the following is a logical hypothesis based on the graph shown?
Cells contain more glucose than oxygen.
Oxygen molecules diffuse across the cell membrane faster than water molecules.
Glucose molecules must cross the cell membrane by active transport.
Carbon dioxide crosses the cell membrane faster than glucose.
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