SAT Subject Test: Biology E/M Crash Course

PART I:

INTRODUCTION

Chapter 1

KEYS FOR SUCCESS ON THE

SAT BIOLOGY E/M SUBJECT TEST

OVERVIEW OF THE SAT BIOLOGY E/M SUBJECT TEST

WHY DO STUDENTS TAKE THE SAT BIOLOGY E/M SUBJECT TEST?

Some colleges require or recommend that students take the test for admission to the college, or to specific majors and special programs. If you plan to attend college, performing well on the SAT Biology E/M Subject Test can enhance your application by demonstrating your proficiency in biology. The test is highly recommended for any student who wants to strengthen his or her college application, as well as homeschooled and other nontraditional students who wish to independently demonstrate academic achievement.

WHAT COURSE WORK IS RECOMMENDED PRIOR TO TAKING THE TEST?

The test is typically taken after a one-year college-preparatory biology course, preferably with laboratory experience, and a one-year course in algebra. Although prior study in these courses is the essential foundation of your knowledge, intimate familiarity with the testing format, the specific content and skills required, and the types of questions used on the test is essential for a successful outcome.

WHO ADMINISTERS THE TEST AND WHERE IS IT GIVEN?

The SAT Biology E/M Subject Test is produced by the College Board and administered by Educational Testing Service (ETS). Testing sites are located throughout the United States, usually in high schools. Ask your guidance counselor for additional information or visit the College Board website at sat.collegeboard.org for test locations, fees, and required preregistration.

WHEN IS IT BEST TO TAKE THE TEST?

Generally it is best to take the SAT Biology E/M Subject Test as soon as possible after you have taken your biology course, and after you have conducted a thorough review and familiarized yourself with the test format by taking a number of practice tests under the same conditions as the actual test. In deciding when to take the test, be aware of the application deadlines of the colleges to which you will apply. Double-check those deadlines and then coordinate a testing date that works best for you by visiting the College Board website at the URL provided earlier.

DO I NEED TO BRING A CALCULATOR TO THE TEST?

No. Calculators are not allowed or necessary to take this test. Units of measure are in the metric system.

FORMAT OF THE SAT BIOLOGY E/M SUBJECT TEST

WHAT IS THE FORMAT OF THE TEST AND HOW MUCH TIME IS ALLOTTED?

There are two forms of the test for Biology: Ecological (Biology-E) and Molecular (Biology-M). Each test has a common core of 60 multiple-choice questions. The test you choose will then branch off to present 20 additional multiple-choice questions concentrating on the respective specialized subject matter. You may take both of these tests, but NOT on the same day. Each test must be completed in 60 minutes. Because biology is such a broad discipline, the two alternative tests allow you to choose the area in which you have more familiarity. Choose Biology-E if your strengths are in the areas of ecology and evolution & diversity. Choose Biology-M if your strengths are in the areas of cellular & molecular biology and genetics. If you are not sure, ask your teacher which area was more emphasized in the biology course you took.

WHAT TOPICS ARE COVERED ON THE TEST?

The major topics covered on the SAT Biology E/M Subject Test, and the comparative percentages of emphasis on both versions of the test, are shown in the following table. Further details for each major topic can be found in the Table of Contents.

Major Topics Covered on the SAT Biology E/M Subject Test

WHAT TYPES OF QUESTIONS ARE ON THE TEST?

There are three main types of question on the SAT Biology E/M Subject Test, and they are present in approximately equal numbers. As you complete the practice tests offered by REA, you will become very familiar with each type of question and the different forms they take on the SAT Biology E/M Subject Test.

1. Factual Recall. This type of question asks you to recall a fact. These include matching terms with definitions, matching organisms with characteristics, matching items with their correct descriptions or functions, labeling a figure, etc. A question may use a matching format or an item with five possible answers—only one of which is correct. The content sections of this book will equip you with a valuable store of information to answer these questions.

2. Concept. This type of question asks you to apply a concept in order to answer the question. Examples include working out an inheritance problem in order to determine the ratio of offspring, identifying a similarity or difference between two or more processes, groups, etc., or evaluating the BEST example of a general principle. The clearly explained concepts presented in the content sections of this book will provide you with the background necessary to answer these questions.

3. Analysis. This type of question asks you to analyze and evaluate a set of facts, a situation, a diagram, a set of data, a graph, or an experimental design in order to draw a reasonable conclusion. In these types of questions, you are presented with information and you generally use two main tools to transform that information in some way to reach a sound conclusion: 1) application of the correct concept combined with 2) logical thinking. You often need to be able to read graphs accurately or to construct graphs from raw data. These questions, whether part of a multi-question set, or a single, stand-alone question, take the longest time of all three types to answer because it takes time to read and analyze the information. The skills you will develop and hone by doing a large number of these questions on our practice tests will allow you to approach these types of questions with confidence and arrive at correct conclusions more rapidly.

HOW TO USE THIS BOOK

Step 1: Familiarize yourself with the topics covered on the test. Read through the content-related portions of this book (Chapters 2 to 21) to familiarize yourself with the topics covered on the test. It is not necessary to study the material in depth on your first reading. Your goal should be to refresh your memory of the content you learned in your biology course, and to note any content that may be new to you.

Step 2: Take either the full-length Bio-E or Bio-M practice test provided by REA. You’ll have a choice to practice for Biology-E or Biology-M. Biology-E presents more questions on biological communities, populations, and energy flow. Biology-M stresses biochemistry, cellular structure and processes, such as respiration and photosynthesis. Access the practice tests at the online REA Study Center at www.rea.com/studycenter. Find a comfortable, quiet place to work, with no notes or source materials, and allow yourself 60 minutes to take the test.

Step 3: Evaluate topics for further study. Use the answer key to score your test. For each question you did not answer correctly, mark the specific content area to which it relates in the Table of Contents. For additional help identifying the correct topic to which the question refers, read the answer explanation provided with REA’s practice tests.

Step 4: Study the topics you have identified. Locate the appropriate content, and study that material in depth using the outline and figures. The answer explanations in our practice tests provide additional help in understanding difficult concepts.

Step 5: Work on analysis skills. Use the Special Skills for Experiment-Based Questions (Chapter 22) to review and strengthen your analytical skills.

Step 6: Use your practice test to prepare optimally for the actual test. Follow up your thorough content review by retaking the practice exam at the online REA Study Center. Doing so will allow you to simulate the specific conditions of the SAT Biology E/M Subject Test.

FIRST READ-THROUGH

• Read the first question carefully; read all the answer choices; re-read when necessary for clarification.

• Eliminate all wrong answer choices and cross off their lead-letter (A, B, C, D, or E) with a slash.

• Decide on the right answer choice and then fill in the correct oval for that question.

• If you can’t eliminate all the answer choices on this first read-through, write down the question’s number on your scrap paper, and skip its space on the answer grid.

• Swiftly, but carefully, work on the rest of the questions in order.

• Periodically check to make sure you are keeping your proper place on the answer grid, and to see how much time you have left.

Second Read-Through

• When you come to the end of the test, do a second read-through. Start from the beginning and work only on the questions you left blank on the first read-through.

Final Read-Through

• If you have completed the test and time remains, check over your work to make sure you haven’t made any avoidable errors, such as filling in the wrong oval for any question you answered.

SHOULD I GUESS IF I DON’T KNOW THE ANSWER?

The questions on the SAT Biology E/M Subject Test are ordered so that the questions which are the shortest to read and answer come first. All questions are worth the same: 1 point. Also, you receive 1 point for each correct answer, you lose 1/4 point for each incorrect answer, and you receive no points for each question you leave blank. There are five answer choices for each question. For these reasons, you should definitely do the following:

• Attempt each question in order.

• Take your best guess at any question for which you can eliminate even ONE wrong answer choice.

• Leave any question blank for which you can not eliminate at least one wrong answer choice.

SCORING THE SAT BIOLOGY E/M SUBJECT TEST

The SAT Biology E/M Subject Test, like all SAT Subject Tests, is scored on a 200–800 scale.

HOW DO I SCORE MY PRACTICE TEST?

Your exam is scored by crediting one point for each correct answer and deducting one-fourth of a point for each incorrect answer. There is no deduction for answers that are omitted. Use the worksheet below to calculate your raw score and to record your scores for the practice test you take (Biology-E or Biology-M). To determine your scaled score, you will need to use the score conversion chart for the SAT Biology E/M.

The score conversion chart changes from test to test, but a good estimate for raw score to scaled score ranges is as follows:

WHAT TO DO AS TEST DAY APPROACHES

WHAT SHOULD I DO THE WEEK BEFORE THE TEST?

Briefly re-read the content chapters of this book, paying particular attention to italicized words and phrases, and retake the online practice exam accessible at the REA Study Center. Make sure you know where the test is to be given, and how to get into the building. Make sure you have the materials listed below.

WHAT SHOULD I DO THE DAY BEFORE THE TEST?

Do not study. Exercise. Do something healthy and enjoyable. Don’t worry. Get a good night’s sleep. Be sure to gather the following materials together:

• Your admission ticket

• An acceptable photo ID (visit the College Board website at www.collegeboard.org for a list of acceptable IDs and get your ID in hand well in advance of your test date)

• Two No. 2 pencils with soft erasers

• A watch without an audible alarm

• A snack

• A map to the test site, if necessary

WHAT SHOULD I DO ON THE DAY OF THE TEST?

Bring the materials listed in the previous section. Arrive at the testing site 15 to 20 minutes early to allow yourself time to settle in and get comfortable before the start of the test. Remain confident and relaxed while taking the test. Do your very best!

PART II:

CELLULAR AND MOLECULAR BIOLOGY

Chapter 2

CELL STRUCTURE

AND ORGANIZATION

I.  Key Concepts

A. All organisms are made up of one or more cells.

B. The cell is the basic unit of structure and function of organisms.

C. New cells only arise from existing cells by cell reproduction.

D. Cells exchange substances with their environment by transporting these substances in and out of the cell across the plasma membrane.

II.    There are two main types of cells that are distinctly different.

A. Prokaryotic cells are simpler and more ancient than eukaryotic cells.

1. Prokaryotic cells have no nucleus or membrane-bound organelles.

2. Prokaryotic cells are typically smaller than eukaryotic cells.

B. Eukaryotic cells are those of protists, fungi, plants, and animals.

1. Animal cells are generally smaller than plant cells.

2. Plants have some cellular structures that animals don’t have.

  i. Plants have rigid cell walls made of the polymer, cellulose.

 ii.  Plants have chloroplasts where photosynthesis is carried out.

iii. Many plant cells have a large, central vacuole that is absent in animal cells.

iv. Compare the animal cell diagram (Figure 2.1) to that of the plant cell diagram (Figure 2.2).

Figure 2.1 Animal Cell

Figure 2.2 Plant Cell

Central vacuole Nucleus

III.  The structures and functions of important cell features and organelles are shown in Table 2.1 , with an emphasis on the differences between prokaryotes and eukaryotes, and between plant and animal cells.

Table 2.1 Structures and Functions of Various Cell Types

Know the names, structures and functions of each cellular component and be able to identify each from a figure of a cell.

IV.    Concept: The plasma membrane is a barrier protecting a cell from its immediate environment, but it also must allow substances to be transported into and out of the cell.

A. The plasma membrane is selectively permeable, meaning that it allows some substances to pass through it, but not others.

1. The lipid portion of the membrane is composed mainly of phospholipids.

  i. Phospholipids have a hydrophobic (water-fearing) tail and a hydrophilic (water-loving) head.

 ii. The cytosol and the fluid outside the cell (the extracellular fluid) are both aqueous (watery) environments.

iii. Therefore, phospholipids form a bilayer as shown in Figure 2.3 because the hydrophilic heads associate with the cytoplasm and the extracellular fluid, while the hydrophobic tails associate with each other.

2. In addition, proteins specialized for transporting molecules across the membrane are embedded in the lipid bilayer.

Figure 2.3 Plasma Membrane Structure

B. There are two main types of cellular transport: passive transport and active transport.

1. Passive transport does not require the cell to use ATP energy.

  i. In diffusion, a substance moves down its concentration gradient from an area of higher concentration to an area of lower concentration.

a) Substances moved are small, uncharged molecules (e.g., carbon dioxide and oxygen).

b) Substances move directly across the lipid bilayer.

Figure 2.4 Diffusion

 ii. Osmosis causes water to move across the plasma membrane from a hypotonic solution to a hypertonic solution.

a) A hypotonic solution has a lower concentration of solutes (dissolved substances) than a hypertonic solution.

b) If two solutions have equal concentrations of solutes, they are called isotonic and there is no net movement of water across the plasma membrane. This is called dynamic equilibrium.

c) In osmosis, the solute molecule is not able to cross the semipermeable plasma membrane.

Figure 2.5 Osmosis: Hypertonic, Hypotonic, and Isotonic Cells

iii. Facilitated diffusion moves charged molecules (e.g., potassium ions) and larger molecules (e.g., glucose) into and out of the cell.

a) As with diffusion, facilitated diffusion moves a substance down its concentration gradient from an area of higher concentration to an area of lower concentration without the use of ATP.

b) Unlike diffusion, however, the substance moves with the help of carrier proteins or through a channel protein.

Figure 2.6 Facilitated Diffusion Uses Carrier or Channel Proteins

2. Active transport requires the cell to use ATP.

  i. The sodium–potassium pump is a type of carrier protein called a cell membrane pump. A pump requires energy to move substances (in the present case, sodium ions: Na+ and potassium ions: K+) against their concentration gradients from areas of low concentration to areas of high concentration.

a) The Na+-P+ pump is important to animal cells, which must maintain a difference in charge across the plasma membrane.

b) The Na+–P+ pump moves 3 Na+ out of the cell, while at the same time moving 2 K+ into the cell.

c) The pump picks up 3 Na+ on the inside of the cell and then changes shape, causing it to deposit them outside the cell after ATP adds a phosphate to the pump.

d) By a similar shape change, the pump moves 2 K+ in the opposite direction as the phosphate group leaves the pump protein.

Figure 2.7 The Sodium–Potassium Pump

 ii. Exocytosis and endocytosis move large molecules and food particles, etc., across the plasma membrane with the expenditure of ATP.

a) Exocytosis is the process whereby newly synthesized proteins and other molecules to be exported are carried in vesicles from the ER and Golgi apparatus to the plasma membrane.

b) The membrane of the vesicle then fuses with the plasma membrane, expelling its contents to the exterior of the cell.

c) In the opposite process—endocytosis—substances are taken up by a small in-folding of the plasma membrane and are incorporated into a vesicle.

d) Pinocytosis is the uptake of liquids, while phagocytosis is the uptake of solid substances.

Figure 2.8 Endocytosis and Exocytosis

Know the names of the different types of transport, how they operate, and whether they require the use of ATP.

Chapter 3

MITOSIS

I.  Key Concepts

A. The number of chromosomes an organism has in its body cells does not vary from cell to cell, nor does it vary from organism to organism of the same species.

B. The genetic material of all organisms is contained on chromosomes that become especially compact during cell reproduction.

C. The cell cycle is the life cycle of a cell and includes time periods when a cell is not dividing as well as those when it undergoes cell division.

D. Mitosis occurs in eukaryotes and produces cells with nearly identical genetic makeup.

1. Mitosis is used for the purpose of organismal reproduction in single-celled organisms.

2. It is used for the purposes of development and cell replacement in the normal growth and maintenance of the bodies of multicellular organisms.

E. Prokaryotes generally reproduce by a process called binary fission.

II.    Chromosomes contain the genetic material (DNA), and are found in the nucleus of a eukaryotic cell.

A. All the cells of animals and plants, except sperm and egg cells, are called somatic cells, and each somatic cell has the same number of chromosomes.

B. Each member of a species generally has the same number of chromosomes.

C. Most sexually reproducing organisms have pairs of autosomes and sex chromosomes. For example:

1. Humans have 46 chromosomes, grouped into 23 pairs.

  i. Humans have 22 pairs of autosomes.

a) Each pair of autosomes is called a homologous pair.

b) For each of these 22 autosomal pairs, one homologue of the pair was inherited from the father and the other homologue was inherited from the mother.

c) The two chromosomes of a pair are called homologous because each has genes for the same set of characteristics in the same locations along their (relatively) equal lengths.

 ii. The other pair of human chromosomes, X and Y, are called the sex chromosomes.

a) A male inherits one X chromosome from his mother and one Y chromosome from his father (XY).

b) A female inherits two X chromosomes, one from each parent (XX).

c) The two sex chromosomes are not homologous because they do not contain genes for the same set of characteristics along their entire lengths and are of different sizes.

iii. A karyotype is a photograph of an organism’s highly compact chromosomes that have been prepared from cells undergoing mitosis (and are therefore duplicated); the images of the chromosomes are then cut from the photograph and arranged from largest to smallest.

Figure 3.1 Karyotype: Autosomal and Sex Chromosomes of a Human Female