Chapter 7 Test Bank

Multiple Choice Identify the choice that best completes the statement or answers the question.

____ 1. Who used a compound microscope to see chambers within cork and named them “cells”? a. Anton van Leeuwenhoek b. Robert Hooke c. Matthias Schleiden d. Rudolf Virchow ____ 2. What advance in technology made the discovery of cells possible? a. the centrifuge b. the particle accelerator c. the ultraviolet light d. the microscope ____ 3. Which of the following is NOT a principle of the cell theory? a. Cells are the basic units of life. b. All living things are made of cells. c. Very few cells are able to reproduce. d. All cells are produced from existing cells. ____ 4. Which of these is NOT true of cells? a. They are much like empty rooms. b. They were first discovered in the 1600s. c. They can be found in pond water. d. They contain a huge array of working parts. ____ 5. Electron microscopes can reveal details a. only in specimens that are still alive. b. about the different colors of cell structures. c. of cell structures only once they are stained. d. 1000 times smaller than those visible in light microscopes. ____ 6. Which type of microscope can produce three-dimensional images of a cell’s surface? a. transmission electron microscope b. scanning electron microscope c. simple light microscope d. compound light microscope ____ 7. Colors seen in images made from electron microscopes are a. true to life. b. the colors of electrons. c. added to make certain structures easier to see. d. added so scientists can trace living cells through the body. ____ 8. Looking at a cell under a microscope, you note that it is a prokaryote. How do you know? a. The cell lacks cytoplasm. b. The cell lacks a cell membrane. c. The cell lacks a nucleus. d. The cell lacks genetic material. ____ 9. Which of the following enclose their DNA in a nucleus? a. prokaryotes b. bacteria c. eukaryotes d. viruses ____ 10. Not all cells are alike. Which of the following is NOT a true statement about differences between cells? a. Cells come in many different shapes. b. Different kinds of cells are different sizes. c. Some cells have a nucleus, but others do not. d. Most cells have a membrane, but some do not. ____ 11. Which of the following organisms are prokaryotes? a. plants b. animals c. bacteria d. fungi

Figure 7–1

____ 12. Which of the following conclusions could you draw about the cell shown in Figure 7–1? a. The cell is eukaryotic because it has a nucleus. b. The cell is prokaryotic because it has a nucleus. c. The cell is eukaryotic because it does not have a nucleus. d. The cell is prokaryotic because it does not have a nucleus. ____ 13. Which of the following is a function of the nucleus? a. stores DNA b. stores sugars c. builds proteins d. packages proteins ____ 14. Which of the following best describes the relationship between the nucleus and the cytoplasm? a. The cytoplasm is a fluid that fills the inside of the nucleus. b. The cytoplasm is an organelle that is usually found near the nucleus. c. The nucleus is an organelle that is surrounded by the cytoplasm. d. The nucleus is a fluid and it mixes with the fluid cytoplasm. ____ 15. Which of the following statements about the nucleus is NOT true? a. The nucleus stores the coded instructions for making the cell’s proteins. b. The nucleus usually contains a nucleolus region which is where ribosome assembly begins. c. The nucleus is the site of protein assembly. d. The nucleus is surrounded by a nuclear envelope that lets materials in and out. ____ 16. Which organelle breaks down organelles that are no longer useful? a. Golgi apparatus b. lysosome c. endoplasmic reticulum d. mitochondrion ____ 17. Which of the following is a function of the cytoskeleton? a. helps a cell keep its shape b. contains DNA c. surrounds the cell d. helps make proteins ____ 18. Which structures are involved in cell movement? a. cytoplasm and ribosomes b. nucleolus and nucleus c. microtubules and microfilaments d. chromosomes

Figure 7–2

____ 19. Which structure in the cell shown in Figure 7–2 above stores materials, such as water, salts, proteins, and carbohydrates? a. structure A b. structure B c. structure C d. structure D ____ 20. Which structure makes proteins using coded instructions that come from the nucleus? a. Golgi apparatus b. mitochondrion c. vacuole d. ribosome ____ 21. Which sequence correctly traces the path of a protein in the cell? a. ribosome, endoplasmic reticulum, Golgi apparatus b. ribosome, endoplasmic reticulum, chloroplast c. endoplasmic reticulum, lysosome, Golgi apparatus d. ribosome, Golgi apparatus, endoplasmic reticulum

Figure 7–3

____ 22. Which structure in the cell shown in Figure 7–3 above modifies, sorts, and packages proteins and other materials for storage or release from the cell? a. structure A b. structure B c. structure C d. structure D ____ 23. Which organelle converts the chemical energy stored in food into compounds that are more convenient for the cell to use? a. chloroplast b. Golgi apparatus c. endoplasmic reticulum d. mitochondrion ____ 24. Which organelles are involved in energy conversion? a. mitochondria and chloroplasts b. mitochondria and ribosomes c. smooth and rough endoplasmic reticulum d. Golgi apparatus and chloroplasts ____ 25. Which organelle would you expect to find in plant cells but not animal cells? a. mitochondrion b. ribosome c. chloroplast d. smooth endoplasmic reticulum ____ 26. The primary function of the cell wall is to a. support and protect the cell. b. store DNA. c. direct the activities of the cell. d. help the cell move. ____ 27. Unlike the cell membrane, the cell wall is a. found in all organisms. b. composed of a lipid bilayer. c. selectively permeable. d. a rigid structure. ____ 28. You will NOT find a cell wall in which of these kinds of organisms? a. plants b. animals c. fungi d. bacteria ____ 29. Which of the following structures serves as the cell’s boundary from its environment? a. mitochondrion b. cell membrane c. chloroplast d. channel protein ____ 30. Which of the following is a function of the cell membrane? a. breaks down lipids, carbohydrates, and proteins from foods b. stores water, salt, proteins, and carbohydrates c. keeps the cell wall in place d. regulates the movement of materials into and out of the cell ____ 31. The cell membrane contains channels and pumps that help move materials from one side to the other. What are these channels and pumps made of? a. carbohydrates b. lipids c. bilipids d. proteins ____ 32. Diffusion occurs because a. molecules are attracted to one another. b. molecules constantly move and collide with each other. c. cellular energy forces molecules to collide with each other. d. cellular energy pumps molecules across the cell membrane. ____ 33. During diffusion, when the concentration of molecules on both sides of a membrane is the same, the molecules will a. move across the membrane to the outside of the cell. b. stop moving across the membrane. c. continue to move across the membrane in both directions. d. move across the membrane to the inside of the cell. ____ 34. The diffusion of water across a selectively permeable membrane is called a. osmotic pressure. b. osmosis. c. pinocytosis. d. active transport. ____ 35. An animal cell that is surrounded by fresh water will burst because the osmotic pressure causes a. water to move into the cell. b. water to move out of the cell. c. solutes to move into the cell. d. solutes to move out of the cell. ____ 36. Which means of particle transport requires input of energy from the cell? a. diffusion b. osmosis c. facilitated diffusion d. active transport

Figure 7–4

____ 37. Which means of particle transport is shown in Figure 7–4 above? a. diffusion b. osmosis c. facilitated diffusion d. active transport

Figure 7–5

____ 38. Which means of particle transport is shown in Figure 7–5 above? a. endocytosis b. exocytosis c. facilitated diffusion d. protein pump ____ 39. Which of the following activities is NOT a way that unicellular organisms maintain homeostasis? a. reproduction b. growth c. cell specialization d. response to the environment ____ 40. Which term describes the relatively constant internal physical conditions of an organism? a. cell specialization b. homeostasis c. organ system d. unicellularity ____ 41. The cells of unicellular organisms are a. specialized to perform different tasks. b. larger than those of multicellular organisms. c. able to carry out all of the functions necessary for life. d. unable to respond to changes in their environment. ____ 42. Which of the following is an example of an organ? a. heart b. epithelial tissue c. digestive system d. nerve cell ____ 43. A group of similar cells that perform a particular function is called a. an organ. b. an organ system. c. a tissue. d. a division of labor. ____ 44. An organ system is a group of organs that a. are made up of similar cells. b. are made up of similar tissues. c. work together to perform a specific function. d. work together to perform all the functions in a multicellular organism. ____ 45. Which list represents the levels of organization in a multicellular organism from the simplest level to the most complex level? a. cell, tissue, organ system, organ b. organ system, organ, tissue, cell c. tissue, organ, organ system, cell d. cell, tissue, organ, organ system

Modified True/False Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.

____ 1. Viruses are not made up of cells. Therefore, viruses are not considered to be living things. ______

____ 2. A scanning electron microscope allows light to pass through a specimen and focuses it using two lenses to form an image. ______

____ 3. Prokaryotic and eukaryotic cells are surrounded by a thin, flexible barrier called a cell membrane. ______

____ 4. The assembly of ribosomes begins in a small dense structure called the chromatin. ______

____ 5. Flagella made up of microtubules help organize cell division. ______

____ 6. Cilia and flagella are made of protein filaments called endoplasmic reticulum. ______Figure 7–6

____ 7. Structure D represented in Figure 7–6 is the smooth endoplasmic reticulum. ______

____ 8. Ribosomes that synthesize proteins are found on the smooth endoplasmic reticulum. ______

____ 9. Plant cells have chloroplasts but not mitochondria. ______

____ 10. Water, carbon dioxide, oxygen, and some other substances can pass through the cell wall. ______

____ 11. Once equilibrium is reached, roughly equal numbers of molecules move in either direction across a semipermeable membrane, and there is no further change in concentration on either side of the membrane. ______

____ 12. Proteins called aquaporins are important to the movement of water through cell membranes. These proteins participate in active transport. ______

____ 13. Moving materials from an area of low concentration to an area of high concentration requires active transport. ______

____ 14. A cell in a multicellular organism must be able to carry out all of the functions necessary for life in order for the organism to survive. ______

____ 15. There is a division of labor among the cells of multicellular organisms. ______

Completion Complete each statement.

1. According to the cell theory, all cells come from existing ______.

2. Electrons pass through thin slices of cells or tissues and produce flat, two-dimensional images in ______electron microscopy.

3. Depending on whether they have a ______, unicellular organisms are classified as either eukaryotes or prokaryotes. Figure 7–7

4. The small, dense region indicated in Figure 7–7 by the letter D is called the ______.

5. Most of the time, the cell’s genetic information is found as threadlike ______in the cell’s nucleus.

Figure 7–6

6. The storage structure indicated in Figure 7–6 by the letter F is a(an) ______.

7. Cells that need to make a lot of protein are expected to have a large number of ______.

8. In plants, ______capture energy from sunlight and convert it into chemical energy, whereas ______convert chemical energy into compounds that are convenient for the cell to use.

9. The cell takes in food and water and eliminates wastes through its selectively permeable ______.

10. Molecules tend to move from an area where they are more concentrated to an area where they are less concentrated. This process is called ______.

11. Large molecules, such as glucose, that cannot cross the lipid bilayer can still move across the membrane through a type of passive transport called ______.

12. Some materials can move across the cell membrane against a concentration gradient by ______. 13. A cell’s relatively constant internal physical and chemical conditions are called ______.

14. The cells in a multicellular organism have specific jobs. This is called cell ______.

15. Cells within a multicellular organism communicate by chemical signals. In order to receive and respond to a certain chemical signal, a cell must have a ______for that chemical.

Short Answer

1. What does the cell theory say?

2. What kinds of microscopes could you use to look at the structure of DNA? Could you study the structure of DNA in a living specimen? Why or why not?

Figure 7–8

3. Is the cell in Figure 7–8 above a prokaryote or a eukaryote? What features help you determine your answer?

4. How do prokaryotes and eukaryotes differ?

5. How is the nucleus of a cell like the main office of a large factory?

6. List two functions of the cytoskeleton. Figure 7–7

7. Identify each of the cell structures indicated in Figure 7–7. Use these terms: nucleus, mitochondrion, ribosome, cell membrane, smooth endoplasmic reticulum, rough endoplasmic reticulum, nucleolus, Golgi apparatus, cytoplasm.

Figure 7–9

8. Which structures in the cells shown in Figure 7–9 above are responsible for meeting the cells’ energy needs? Based on the presence or absence of these structures, identify which cell is a plant cell.

9. What advantages do cell walls provide plant cells that contact fresh water?

10. What would happen if a cell’s membrane became impermeable?

11. Suppose you add a teaspoon of sugar to a cup of coffee, and the sugar molecules disperse themselves throughout the hot coffee. What process has occurred? How do you know?

12. Explain, in terms of osmosis, why a raisin placed in a cup of pure water overnight will puff up with water.

13. What would happen to an animal cell with an internal salt concentration of 0.8% if it were placed in a salt solution with a concentration of 0.2%? Why?

14. How are endocytosis and exocytosis similar? How are they different?

15. List the four levels of organization in a multicellular organism in order from simplest to most complex.

Science Skills A student put together the experimental setup shown below. The selectively permeable membrane is permeable to water, but not the solute shown.

Figure 7–10

1. Interpret Visuals Describe the experimental setup shown in Figure 7–10.

2. Compare and Contrast How does the solution on Side A of the apparatus shown in Figure 7–10 differ from the solution on Side B?

3. Predict Look at Figure 7–10. Describe the movement of water in the experimental setup. What will happen to the concentration of water over time?

4. Predict What will the apparatus shown in Figure 7–10 look like when equilibrium is reached?

5. Predict Once equilibrium is reached in the apparatus shown in Figure 7–10, will the water molecules continue to move? Explain your answer.

Figure 7–11

6. Interpret Visuals Which drawing in Figure 7–11, I or II, contains structures that carry out photosynthesis? What is this structure labeled in the diagram?

7. Compare and Contrast Look at Figure 7–11. Which structure in drawing I corresponds to structure L in drawing II? What is the name of this structure? 8. Compare and Contrast Which three structures are found in drawing II of Figure 7–11 but not in drawing I? What are the names of these structures?

9. Interpret Visuals Which organelle is labeled K in Figure 7–11? What is the function of this organelle?

10. Interpret Visuals Do the drawings in Figure 7–11 represent prokaryotes or eukaryotes? How do you know?

The experimental setup below shows an osmometer. An osmometer is a device used to measure the amount of osmotic pressure exerted by a liquid passing through a semipermeable membrane. The graph shows one lab group’s results compared with the results of the rest of the class combined. Line A represents the results of the single lab group. Line B represents the data of the rest of the class.

Figure 7–12

11. Compare and Contrast Look at the graph in Figure 7–12. Compare the lab results of the single lab group with those collected by the rest of the class.

12. Analyze Data Which results in the graph in Figure 7–12 are more likely to be accurate, those represented by line A or by line B? Why?

13. Evaluate and Revise What could account for the difference in lines A and B in the graph in Figure 7–12?

14. Predict Look at the graph in Figure 7–12. How would the results differ if a sucrose solution with twice the concentration of the one used to collect the results represented by line A were used?

15. Calculate How might you use the graph in Figure 7–12 to calculate the rate of osmosis observed? What units would you use to report the rate?

Essay 1. Summarize three statements from the cell theory. Explain the significance of the cell theory to biology.

2. Describe the cell membrane, cell wall, nucleus, and cytoplasm. Which of these structures are you likely to find in a prokaryotic cell? Eukaryotic cell? Plant cell? Animal cell?

3. Distinguish between microtubules and microfilaments. Describe two functions of each kind of structure.

4. Compare and contrast the structure and function of the cell wall with that of the cell membrane.

5. Why is the cell membrane sometimes compared to mosaic art?

Figure 7-13

6. The diagrams in Figure 7-13 above show a normal blood cell before and after it is placed in a solution. Describe what could cause the cell to react the way that it did.

7. What are aquaporins? How are they important to cells?

8. How do facilitated diffusion and active transport differ? Is osmosis an example of facilitated diffusion or active transport?

9. Compare a cell from a unicellular organism with a cell from a multicellular organism in terms of cell specialization.

10. Discuss the levels of organization in multicellular organisms and explain why these levels are not used to describe unicellular organisms. Chapter 7 Test Bank Answer Section

MULTIPLE CHOICE

1. ANS: B PTS: 1 BLM: knowledge 2. ANS: D PTS: 1 BLM: comprehension 3. ANS: C PTS: 1 BLM: comprehension 4. ANS: A PTS: 1 BLM: synthesis 5. ANS: D PTS: 1 BLM: knowledge 6. ANS: B PTS: 1 BLM: comprehension 7. ANS: C PTS: 1 BLM: comprehension 8. ANS: C PTS: 1 BLM: application 9. ANS: C PTS: 1 BLM: knowledge 10. ANS: D PTS: 1 BLM: comprehension 11. ANS: C PTS: 1 BLM: comprehension 12. ANS: A PTS: 1 BLM: application 13. ANS: A PTS: 1 BLM: knowledge 14. ANS: C PTS: 1 BLM: synthesis 15. ANS: C PTS: 1 BLM: analysis 16. ANS: B PTS: 1 BLM: comprehension 17. ANS: A PTS: 1 BLM: knowledge 18. ANS: C PTS: 1 BLM: application 19. ANS: C PTS: 1 BLM: application 20. ANS: D PTS: 1 BLM: comprehension 21. ANS: A PTS: 1 BLM: application 22. ANS: A PTS: 1 BLM: application 23. ANS: D PTS: 1 BLM: knowledge 24. ANS: A PTS: 1 BLM: synthesis 25. ANS: C PTS: 1 BLM: comprehension 26. ANS: A PTS: 1 BLM: knowledge 27. ANS: D PTS: 1 BLM: analysis 28. ANS: B PTS: 1 BLM: knowledge 29. ANS: B PTS: 1 BLM: knowledge 30. ANS: D PTS: 1 BLM: comprehension 31. ANS: D PTS: 1 BLM: synthesis 32. ANS: B PTS: 1 BLM: comprehension 33. ANS: C PTS: 1 BLM: comprehension 34. ANS: B PTS: 1 BLM: knowledge 35. ANS: A PTS: 1 BLM: application 36. ANS: D PTS: 1 BLM: comprehension 37. ANS: D PTS: 1 BLM: application 38. ANS: A PTS: 1 BLM: application 39. ANS: C PTS: 1 BLM: comprehension 40. ANS: B PTS: 1 BLM: knowledge 41. ANS: C PTS: 1 BLM: comprehension 42. ANS: A PTS: 1 BLM: application 43. ANS: C PTS: 1 BLM: knowledge 44. ANS: C PTS: 1 BLM: comprehension 45. ANS: D PTS: 1 BLM: analysis

MODIFIED TRUE/FALSE

1. ANS: T PTS: 1 BLM: application 2. ANS: F, light

PTS: 1 BLM: comprehension 3. ANS: T PTS: 1 BLM: knowledge 4. ANS: F, nucleolus

PTS: 1 BLM: comprehension 5. ANS: F, centrioles

PTS: 1 BLM: comprehension 6. ANS: F, microtubules

PTS: 1 BLM: comprehension 7. ANS: F, rough

PTS: 1 BLM: application 8. ANS: F, rough

PTS: 1 BLM: comprehension 9. ANS: F, and

PTS: 1 BLM: synthesis 10. ANS: T PTS: 1 BLM: comprehension 11. ANS: T PTS: 1 BLM: comprehension 12. ANS: F passive transport facilitated diffusion osmosis

PTS: 1 BLM: comprehension 13. ANS: T PTS: 1 BLM: synthesis 14. ANS: F, unicellular

PTS: 1 BLM: synthesis 15. ANS: T PTS: 1 BLM: comprehension

COMPLETION

1. ANS: cells PTS: 1 BLM: comprehension 2. ANS: transmission

PTS: 1 BLM: comprehension 3. ANS: nucleus

PTS: 1 BLM: synthesis 4. ANS: nucleolus

PTS: 1 BLM: knowledge 5. ANS: chromosomes

PTS: 1 BLM: comprehension 6. ANS: vacuole or central vacuole

PTS: 1 BLM: synthesis 7. ANS: ribosomes

PTS: 1 BLM: analysis 8. ANS: chloroplasts, mitochondria

PTS: 1 BLM: synthesis 9. ANS: cell membrane

PTS: 1 BLM: comprehension 10. ANS: diffusion

PTS: 1 BLM: knowledge 11. ANS: facilitated diffusion

PTS: 1 BLM: synthesis 12. ANS: active transport

PTS: 1 BLM: comprehension 13. ANS: homeostasis

PTS: 1 BLM: knowledge 14. ANS: specialization

PTS: 1 BLM: knowledge 15. ANS: receptor

PTS: 1 BLM: comprehension

SHORT ANSWER

1. ANS: The cell theory says that all living things are composed of cells. It also says that cells are the basic units of structure and function in living things and that new cells come from existing cells.

PTS: 1 BLM: knowledge 2. ANS: DNA is too small to see with a light microscope, so an electron microscope is needed to examine its structure. Electron microscopes cannot be used to look at living specimens, so the structure of DNA cannot be studied in a living specimen.

PTS: 1 BLM: application 3. ANS: This cell is a prokaryote. It has a cell wall, indicated by the letter B, and its DNA, indicated by the letter C, is not enclosed in a nucleus.

PTS: 1 BLM: evaluation 4. ANS: Prokaryotes are generally simpler and smaller than eukaryotes, whereas eukaryotes enclose their DNA in a nucleus and have other specialized organelles.

PTS: 1 BLM: analysis 5. ANS: The nucleus is the control center of the cell and contains nearly all the cell’s DNA, which gives the cell the instructions it needs to make proteins and other molecules.

PTS: 1 BLM: analysis 6. ANS: The cytoskeleton helps the cell maintain its shape and internal organization. It is also involved in many forms of cell movement.

PTS: 1 BLM: knowledge 7. ANS: (A) rough endoplasmic reticulum; (B) cytoplasm; (C) smooth endoplasmic reticulum; (D) nucleolus; (E) nucleus; (F) mitochondrion; (G) Golgi apparatus; (H) ribosome; (I) cell membrane

PTS: 1 BLM: application 8. ANS: The structure identified with the letter E is a chloroplast, which captures energy from sunlight and converts it into chemical energy. The structures identified with the letter D are mitochondria, which convert chemical energy into compounds more convenient for the cell to use. The cell with the chloroplasts is a plant cell.

PTS: 1 BLM: evaluation 9. ANS: Cell walls protect the plant cells from expanding even under tremendous osmotic pressure.

PTS: 1 BLM: synthesis 10. ANS: The cell would die because needed nutrients, such as food and water, could not get inside the cell and wastes would accumulate inside the cell.

PTS: 1 BLM: evaluation 11. ANS: Diffusion has occurred; because diffusion is the movement of a substance from an area of high concentration to an area of lower concentration.

PTS: 1 BLM: application 12. ANS: Because the concentration of water in the cup is greater than the concentration of water in the raisin, water will flow from the cup into the raisin.

PTS: 1 BLM: application 13. ANS: The cell would swell and burst, because the 0.2% salt solution is hypotonic with respect to the cell, causing a net movement of water into the cell.

PTS: 1 BLM: synthesis 14. ANS: Both are forms of active transport of large molecules carried out by movements of the cell membrane. Endocytosis involves taking material into the cell, whereas exocytosis involves moving material out of the cell.

PTS: 1 BLM: analysis 15. ANS: cell, tissue, organ, organ system

PTS: 1 BLM: knowledge

SCIENCE SKILLS

1. ANS: The experimental setup shows a solution with differing concentrations of solute separated by a selectively permeable membrane. The membrane is permeable to water but not the solute.

PTS: 1 BLM: analysis 2. ANS: The solution on Side A has fewer solute particles than the solution on Side B. Both solutions have the same amount of water, so the solution on Side A is hypotonic compared to the solution on Side B.

PTS: 1 BLM: analysis 3. ANS: The membrane is permeable to water so water can cross the membrane in both directions. Over time, there will be a net movement of water toward Side B, which has a higher concentration of solute particles.

PTS: 1 BLM: application 4. ANS: At equilibrium, Side A will have less water than Side B and the concentration of solute molecules will be equal on either side of the selectively permeable membrane.

PTS: 1 BLM: analysis 5. ANS: Yes, the water molecules will continue to move across the membrane; however, there will not be a net movement from one side to the other.

PTS: 1 BLM: application 6. ANS: Drawing II—a plant cell—contains the structure described (a chloroplast). The structure is labeled N.

PTS: 1 BLM: knowledge 7. ANS: Structure I. They both represent the cell membrane.

PTS: 1 BLM: analysis 8. ANS: Structures J, N, and O. Structure J is the cell wall, structure N is a chloroplast, and structure O is a vacuole.

PTS: 1 BLM: analysis 9. ANS: The organelle labeled K is the nucleus. The nucleus stores DNA and directs the activities of the cell.

PTS: 1 BLM: knowledge 10. ANS: Both drawings represent eukaryotes, as shown by the presence of a nucleus.

PTS: 1 BLM: application 11. ANS: Line A shows that the single group’s results are quite different from the results of the rest of the class. Over a half-hour period, the lab group found that the solution traveled 25 mm, whereas the rest of the class found a distance of only 12 mm over the same period of time. The distance traveled in the lab group’s data also kept increasing, whereas the class’ data leveled out at about 10 minutes.

PTS: 1 BLM: analysis 12. ANS: The rest of the class’s results (line B) are more likely to be accurate because they represent a larger sample size.

PTS: 1 BLM: evaluation 13. ANS: The lab group (line A) might have used a more concentrated solution of sucrose or a membrane with a different permeability.

PTS: 1 BLM: evaluation 14. ANS: The more concentrated the solution, the longer distance the solution will travel over the same period of time. Thus, a more concentrated solution would produce a longer distance.

PTS: 1 BLM: synthesis 15. ANS: The rate of osmosis could be calculated by dividing the distance traveled by time. The units would be mm/min. PTS: 1 BLM: analysis

ESSAY

1. ANS: The cell theory states that all living things are composed of cells. It also says that cells are the basic units of structure and function in living things, and that new cells come from existing cells. The cell theory is significant to biology because all living thing are made of cells. Differences in the structure and function of different life forms are reflected in differences in their cell structures.

PTS: 1 BLM: analysis 2. ANS: The cell membrane is a thin, flexible barrier around the cell. The cell wall is a strong layer that surrounds the cell membrane in some cells. The nucleus is a large structure found in some cells. It contains the cell’s genetic material and controls the cell’s activities. The fluid portion of the cell outside the nucleus (if present), is the cytoplasm. All cells have a cell membrane and cytoplasm. Only eukaryotes have a nucleus. Animal cells do not have a cell wall, but plant cells and some prokaryotes do.

PTS: 1 BLM: synthesis 3. ANS: Microtubules are hollow tubes of protein that help maintain the shape of a cell. Microtubules also make up cilia and flagella, which function in cell movement. Microfilaments are long, thin fibers that are narrower than microtubules. Microfilaments function in the movement and support of the cell.

PTS: 1 BLM: synthesis 4. ANS: The cell wall lies outside the cell membrane of many cells, including those of plants, algae, and fungi. It supports and protects the cell and often allows water, oxygen, carbon dioxide, and other materials to pass through it. Most cell walls are rigid and made of carbohydrates and proteins. In contrast, the cell membrane is a thin, flexible membrane made of a lipid bilayer with proteins that run through it and carbohydrate chains attached to proteins poking out on the outer surface of the cell membrane. Like the cell wall, the cell membrane provides protection and support to the cell and allows materials to pass through it. In fact, the cell membrane regulates the movement of materials into and out of the cell.

PTS: 1 BLM: analysis 5. ANS: Like a piece of mosaic art, which is made of different tiles, the cell membrane is made up of many different kinds of molecules. The background is a lipid bilayer. Within this bilayer are proteins that form channels and pumps that help move materials from one side of the membrane to the other. Carbohydrates on the outer surface of the membrane act like chemical identification cards and allow cells to identify one another.

PTS: 1 BLM: analysis 6. ANS: When a normal red blood cell is placed in a hypertonic solution, one that has a higher solute concentration than inside the cell, there is a net movement of water out of the cell. The cell will shrink due to osmotic pressure.

PTS: 1 BLM: application 7. ANS: Aquaporins are proteins that form channels in cell membranes. These channels allow water molecules to pass through the membrane. This is important because the lipid bilayer that makes up cell membranes is hydrophobic, so water molecules have a hard time getting through it. Aquaporins allow water to pass through the membrane by facilitated diffusion.

PTS: 1 BLM: application 8. ANS: Facilitated diffusion involves the movement of molecules across a membrane through protein channels. The molecules move from an area of high concentration to an area of lower concentration. Facilitated diffusion does not require additional energy. Active transport is the movement of particles across the cell membrane using energy. Molecules can move from an area of low concentration to an area of higher concentration in active transport. Osmosis is an example of facilitated diffusion.

PTS: 1 BLM: analysis 9. ANS: The cell from the unicellular organism carries out all the life processes of the organism. It is not specialized. The cell from the multicellular organism is specialized and carries out only certain functions in the organism, while relying on other cells in the multicellular organism to complete other life processes.

PTS: 1 BLM: analysis 10. ANS: The levels of organization in a multicellular organism include cells, tissues, organs, and organ systems. Similar cells are grouped into tissues; tissues that work together form organs; a group of organs that work together make up an organ system. Unicellular organisms cannot have cell specialization. Instead, all of the activities of the organism must be carried out by the single cell.

PTS: 1 BLM: analysis