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March 8-12, 2021 Barton, Somosa, Yonnie 1

5 Unit Overview: Human Biology 5.3 Reproduction & Development

5.3.1 Males & Females: Study 5.3.2 Males & Females: Lesson QUIZ Scoring: 20 points 5.3.3 Fertilization & Development: Study 5.3.4 Fertilization & Development: Lesson QUIZ Scoring: 20 points

5.4 Human Biology

5.4.1 The Effects of Antibiotics 5.4.2 The Effects of Antibiotics Scoring: 20 points

_____________________________________________________________________________________________________ Instructions: Read each question and answer choice carefully. Choose the ONE best answer. Use CAPITAL letters to record your answers on this page.

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Students please annotate, by highlighting or underlining, words or sentences in the Study sections to show that you have read and studied the study sections prior to taking the quizzes.

5.3 Reproduction & Development

Reproduction and Development This lesson will introduce you to the human reproductive system. Humans reproduce sexually. This means that a new human receives half of its genetic information from its father in the form of a sperm. The other half comes from its mother in the form of an egg. The male and female reproductive systems are designed to produce these specialized sex cells, bring the sperm and egg together, and to house a developing baby until birth. Objectives

• Describe the basic anatomy and physiology of the human reproductive system.

• Explain the process of human development from fertilization to birth and major changes that occur in each trimester of pregnancy.

• Describe how, through cell division, cells can become specialized for specific functions.

5.3.1

Males and Females Humans have many traits and behaviors related to reproduction. Many human traits are related to reproduction. We also have many social behaviors designed to attract the opposite sex (gender). Biologically, it is all about reproduction and the passing on of genes. Reproductive Systems The parts of the male and female reproductive systems work together as one human reproductive system.

The male and female reproductive systems come together to make babies. Male and female bodies are different. One of the primary differences is between the male and female reproductive systems. Human beings reproduce sexually, which means that half of a baby's genes come from its mother, and the other half come from its father. This mixing process leads to genetic diversity in the human population. Sperm are produced by the male reproductive system, and eggs are produced in the female reproductive system. When sperm and an egg meet, a baby begins to form. So in fact, there's really only one human reproductive system — a combination of the male and female reproductive systems. Male Reproductive Function The male reproductive system builds sperm, produces semen, and transfers semen and sperm. Sperm carry a male's genetic information. They have tails that allow them to move through a female's body to find an egg. Producing sperm is the primary function of the male reproductive system. In the male, the organs of the reproductive system work together to perform the following major functions:

• build sperm cells



• produce fluid called semen, in which the sperm cells travel • transfer the semen and sperm to the female during intercourse

The male organs must perform another function that is unrelated to reproduction: urination. In addition to sperm, the main parts of the male reproductive system also take urine out of the body. The Path of Sperm Sperm are formed in the testes and leave the male body through ejaculation. In the testes are undifferentiated stem cells. Through the process of meiosis, these stem cells produce sperm with half of the genetic material of the parent cell. It takes about 60 days for an undifferentiated cell to differentiate into a functional sperm cell. After the sperm forms in a seminiferous tubule of a testis, it moves to the epididymis. In the epididymis, sperm gain the ability to swim and fertilize. Puberty Puberty is when a boy's body begins producing more reproductive hormones. Puberty is the period when someone changes from being a child to being physically capable of reproduction. At a certain point in a boy's growth, his brain tells his body to start producing more male reproductive hormones. This is the onset of puberty. It begins with hormones released from the endocrine system. Control of the Male Reproductive System Hormones control the male reproductive system. Reproductive hormones are transforming this male's body from that of a boy into that of a man. Here are the most important male reproductive hormones and their functions:

• testosterone: promotes maturation of the adult male body • follicle-stimulating hormone (FSH): stimulates the testes to produce sperm cells • luteinizing hormone (LH): stimulates the testes to produce more testosterone • gonadotropin-releasing hormone (GnRH): stimulates the production of LH and FSH

Together, these hormones create physical changes in a boy's body, control the production of sperm, and ultimately play an essential role in creating new human beings. You don't need to memorize what each one does, just become familiar with which hormones are a part of the male reproductive system. Interfering with the Male Reproductive System Sperm production is affected by temperature, physical damage, and drug use. Like all systems of the body, the male reproductive system can be harmed by unhealthy activities, physical impact, damaging chemicals, or disease. Sperm production can also be affected by temperature. Sperm need to be kept at slightly below body temperature. Clothing that keeps the testes too close to the body, like briefs, can cause sperm to get too warm and be less active. For a healthy male, this has very little impact on overall sperm count.

This is the moment when Ben Johnson won a gold medal at the 1988 Olympics. But when his urine sample tested positive for steroids, he was stripped of his gold medal. Steroid use, however, is much more damaging than briefs could ever be. Many athletes have been banned from their sport or even had Olympic gold medals taken away from them because of steroid use. Steroids are similar to testosterone, but using steroids can cause a variety of health problems. These problems include the male reproductive system not working properly, cancer, liver damage, and even the growth of breasts!



Female Reproductive Function The female reproductive system receives sperm, combines it with an egg, and grows a baby. The main function of the male reproductive system is to create sperm and deliver it to the female. What about the female reproductive system? There are five major functions of the female reproductive system:

• Creating a supply of eggs • Receiving sperm from the male • Getting an egg fertilized • Developing an embryo • Delivering a baby

Structure and Function The parts of the female reproductive system each play a role in reproduction Like the special cells in the testes that produce sperm, ovaries have special cells that will become eggs. Unlike testes, which produce sperm all the time, ovaries do not produce eggs nonstop.

In fact, when a girl is born, all of her eggs have already been produced. They rest in the ovaries in an undeveloped state until they are ready to be released. One of the ovaries releases an egg into a fallopian tube each month.

A sperm meets an egg in a fallopian tube. The vagina is shaped like the opposite of the male penis. It receives sperm from the male during intercourse. The sperm moves through the cervix and into the fallopian tubes. Did you know sperm can reach an egg even without intercourse? Sperm that is released outside of a woman's body can still find its way into the vagina and the fallopian tubes. If the egg meets a sperm from a male, the fertilized egg will continue down the fallopian tube into the uterus. The uterus houses the growing baby. Female Hormones The female reproductive system is controlled by five main hormones. Like the male reproductive system, the female reproductive system is controlled by specific hormones. Three of these hormones are the same hormones that control the male reproductive system. These hormones have different functions in a male and female, however.

An egg being released within the female reproductive system. This process is controlled by hormones. See if you can remember which hormones are also used in the male reproductive system.

• estrogen stimulates the uterine cycle, regulates FSH, LH, and GnRH, and promotes the development of the adult female body.

• progesterone stimulates the female monthly cycle, and regulates FSH, LH, and GnRH. • follicle-stimulating hormone (FSH) stimulates egg growth and the production of estrogen and progesterone. • luteinizing hormone (LH) causes the release of eggs and stimulates production of estrogen and progesterone. • gonadotropin-releasing hormone (GnRH) stimulates the production of LH and FSH.



Menstrual Cycle Female hormones change in a set pattern each month. The male reproductive system is effective at producing sperm every day. This means that a male is able to fertilize an egg at any time. The female system, on the other hand, has a pattern that repeats about every month. This pattern is called the menstrual cycle. At a certain point in a girl's growth and development, her brain begins to send signals to her endocrine system to begin producing sex hormones. This is the onset of puberty. A female begins to have a menstrual cycle when she goes through puberty. Female Hormone Function The changing levels of female hormones control the monthly changes in the female body. Use the image below as a guide in the following exercise. For each question, look at the levels of each of the hormones in the graph to help answer the questions.

Menstrual Cycle The menstrual cycle consists of menstruation, ovulation, and preparation for potential pregnancy. In the menstrual cycle, there are a few key events. Each of these events is triggered by rising and falling hormone levels. The menstrual cycle is counted starting on the first day of a woman's period, which is considered day 1 in the cycle. Fertility and the Menstrual Cycle The female menstrual cycle determines when a woman is most likely to get pregnant. A woman's ovaries and uterus go through a monthly cycle that includes the development and release of an egg and preparation of the uterus for a growing embryo.

Unlike males, females are not fertile every day of the menstrual cycle. On average, a woman is most likely to get pregnant between days 10 and 15 of her cycle. This is the time period right before and right after the release of the egg. Every woman's body is different and the actual day that the egg is released can vary drastically from woman to woman. Women have been known to get pregnant nearly any day of the month. In fact, women have also been known to get pregnant without actually having intercourse. You'll learn more about the process of fertilization in the next study. Affecting the Menstrual Cycle Many factors can affect a woman's menstrual cycle. There are also many factors, from stress to diet, that affect the female reproductive cycle. Do the following exercise to understand more about the female cycle.



QUIZ 5.3.2 1. What is ovulation? A. When an egg implants into the uterus B. When an egg is produced in the ovary C. When an egg enters the fallopian tube D. When an egg is fertilized

2. Where are the eggs stored? A. Uterus B. Fallopian tube C. Cervix D. Ovary

3. Where does a fertilized egg attach? A. Uterus B. Fallopian tube C. Ovary D. Cervix

4. Which are gametes? A. Vas deferens and testes B. Uterus and epididymis C. Sperm and eggs D. Estrogen and progesterone

5. Which hormone is used by both males and females? A. Luteinizing hormone B. Testosterone C. Progesterone D. Estrogen

6. Which hormone is only used by females? A. Luteinizing hormone B. Estrogen C. Testosterone D. Follicle-stimulating hormone

7. Which hormone is only used by males? A. Follicle-stimulating hormone B. Luteinizing hormone C. Progesterone D. Testosterone

8. How does the body control puberty? A. The nervous system produces gametes. B. The circulatory system produces proteins. C. The endocrine system produces hormones. D. The respiratory system produces a uterus.



9. Which correctly describes a difference between the male and female reproductive systems? A. Males have a monthly cycle. B. Only females produce gametes. C. Females produce gametes less often. D. Only males are fertile.

10. Why do birth control pills contain hormones? A. Female gametes are destroyed by hormones. B. Hormones control the release of eggs. C. Eggs are made of hormones. D. Sperm use hormones to fertilize eggs.

5.3.3 Fertilization and Development An entire human being grows from a single fertilized egg.

These two girls are twins. When two babies grow and develop in one mother at the same time, they are called twins. About three out of every 100 pregnancies are twins. Fertilization Pregnancy begins with fertilization.

The moment of fertilization All pregnancies - whether one, two, or eight babies — begin with fertilization. Fertilization is the meeting of a sperm and an egg. If one fertilized egg goes through cell division, identical twins may result. Non-identical or fraternal twins result from two separate eggs being fertilized by two different sperm. Fertilization happens after one out of a billion sperm meets just one egg. In all multiple births except identical twins, each sperm fertilizes a different egg. Fertilizing the Egg Sperm swim through the fallopian tubes to reach the egg. Up to 1 billion sperm are released to fertilize just one egg. The sperm that reaches the egg first and penetrates the egg's barriers will fertilize the egg. When the DNA of the sperm fuses with the DNA of the egg, it forms a zygote. Zygote to Embryo In the first five days after fertilization, the fertilized cell divides and begins to differentiate. Once the egg and sperm fuse to make a zygote, the zygote begins to divide. In just a few days, the growing organism will develop from one cell to a ball of about 100 cells.



Differentiation The blastocyst contains cells that will become every cell of a developed infant, as well as the cells of the placenta. A blastocyst contains two different types of cells:

• cells that will become the placenta, which attaches to the mother and nourishes the growing baby • cells that will divide and differentiate into every cell of a developed infant's body

About six days after the egg has been fertilized, the blastocyst, now called an embryo, attaches to the inside of the mother's uterus. The placenta begins to develop at the point of connection. The placenta carries food and oxygen from the mother to the growing embryo, and carries waste and carbon dioxide from the embryo back to the mother. Systems Developing Pregnancy is nine months, or three trimesters, long. After the embryo becomes attached to the mother, through the placenta, the countdown to birth begins.

These nine months are often referred to as three trimesters. Each trimester is three months long.

During pregnancy, the cells in the embryo differentiate and multiply. During each trimester, the systems of the

human body become more and more complete. In the rest of this study, you'll learn what happens during each trimester. During which trimester do you think the most development occurs? The First Trimester The first trimester is the most important time of human development. During the first trimester, the growing embryo undergoes dramatic changes. By the time the embryo has been growing for only eight weeks, the beginning of all major organ systems in the body is complete. What does a growing embryo look like during the first trimester? Use the following animation to observe how the embryo changes over the first trimester, and what it looks like at the end of just one trimester.

Milestones of the First Trimester By the end of the first trimester, most of the major development is complete. After one month of growth and development, the cells of the heart and the circulatory system have matured to the point that the heart is beating and blood is pumping. By the end of two months, the embryo has distinct hands and feet, and the teeth have even begun to form. By the end of three months, or the first trimester, the stomach is producing digestive fluids, and external sex organs are formed. Parents often get an ultrasound to see their growing baby. Doctors use the information from an ultrasound to make sure the baby is growing correctly. Second Trimester During the second trimester, major organ systems continue to mature. By the end of the first trimester, much of the major development is complete. So why aren't babies born after three months of pregnancy? Many organ systems, especially the nervous system and respiratory system are still not mature enough to survive life outside of the womb. During the second trimester, the major organ systems — digestive,



respiratory, circulatory, and nervous — continue to mature. In addition, vocal cords, lips, toenails, eyebrows, and eyelashes appear. The mother can also usually feel the baby moving for the first time somewhere near the middle of the second trimester. By the end of the second trimester, all the parts of the eye are developed. Third Trimester During the third trimester, all parts of the fetus's body get much bigger. A baby born at the beginning of the third trimester usually survives, although it would probably need to be hospitalized for a while. The organ systems are mostly complete by the beginning of the third trimester, but during the third trimester everything just gets bigger, preparing the fetus for life outside the mother. The most important change of the third trimester is the beginning of rhythmic breathing movements, which occurs around the eighth month. After this point, even if the baby is born early, its chance of survival is extremely high. Childbirth Childbirth begins with a series of signals between the infant and mother. A complex series of signals between the mother and the baby signal the mother's body to prepare for childbirth. During childbirth, the baby comes out of the mother's body and into life in the world. Most births begin within hours or even days of the first contractions. A contraction is the squeezing of the walls of the mother's uterus. As the uterus contracts, the mother's cervix is slowly opened by the pressure of the baby's head. Eventually, the contractions expel the baby from the mother's body. Fetal Circulation During development, the umbilical cord brings nutrients to the baby.

Umbilical cord Ever wondered why you have a belly button? That marks the spot where your umbilical cord connected to your mother's placenta. While growing in the mother, the fetus receives food, water, and oxygen from the mother's placenta through the umbilical cord. Soon after a baby is born, the umbilical cord is cut. The placenta then detaches from the wall of the uterus and is delivered by the mother. Once the umbilical cord is cut, the baby gets food and oxygen from its environment. The baby's heart and lungs spent nine months getting ready to function on their own. By the time of birth, the heart and lungs of almost all babies function to bring oxygen into the body, and then pump it to all cells of the body. Twins Fraternal and identical twins develop differently. Identical twins result from one fertilized egg splitting into two identical cells that then each develops into a human. This split can take place anytime in the first few weeks of pregnancy. Non-identical or fraternal twins result from two eggs being released at the same time and each being fertilized by a sperm.



STUDY GUIDE 5.3.3



QUIZ 5.3.4 1. What is a zygote?

A. A structure that nourishes the fetus B. A ball of about 100 cells C. A sperm fused with an egg D. An unfertilized egg

2. What happens a few days after fertilization? A. The eye develops. B. The embryo attaches to the mother. C. The blastocyst forms. D. The mother has contractions.

3. How does pregnancy begin? A. The blastocyst differentiates into two cell types. B. A placenta forms in the uterus. C. A sperm reaches an egg in the fallopian tube. D. Contractions begin in the uterine wall.

4. Which happens to a developing child first? A. Growing vocal cords B. Growing functional eyes C. Rhythmic breathing movements D. Development of hands

5. Which best describes what happens to a developing fetus during the third trimester? A. The external sex organs develop. B. The organs grow larger. C. The eyes develop. D. The limbs form.

6. When during fetal development do rhythmic breathing movements begin? A. Early in the second trimester B. When contractions begin C. Just after fertilization D. Late in the third trimester



7. A fetus has been developing for three months. What will happen next? A. External sex organs form. B. The heart starts beating. C. Hands and feet form. D. Eyes develop.

8. How do identical twins form? A. Two sperm fertilize an egg. B. Two eggs are fertilized by two sperm. C. Two eggs are fertilized by one sperm. D. A fertilized egg splits in two.

9. How do the baby's respiration and circulation change when the baby is born? A. The baby's blood has oxygen for the first time. B. It no longer depends on the mother for oxygen. C. The circulatory system pumps blood for the first time. D. The baby now breathes oxygen instead of carbon dioxide.

10. Why are identical twins always the same gender? A. They grew in the same uterus. B. They have the same DNA. C. They were formed by two identical sperm. D. They have the same parents.

5.4.1 Doing Science: Human Biology Medical research improves our quality of life. There are strict ethical rules about using human beings in experiments. To do medical research without harming any human subjects, a scientist combines controlled experiments in a laboratory with observation of actual patients. In this lesson, you will learn about various designs for medical experimentation. Then, in a lab titled "The Effects of Antibiotics," you will collect and classify bacteria, then observe the effects of antibiotics (which are often used in medicine) on different types of bacteria Objectives • Explain the difference between in vitro and in vivo experiments. • Describe the design of an experiment involving real people. • Communicate lab results with your peers in an online discussion.

5.4.1 The Effects of Antibiotics A scientist must observe humans without causing harm. Some medical research is done in a test tube. A human should never be harmed in an experiment. So, how does a scientist use the scientific method to learn about humans and human disease? To do medical research, a scientist observes actual patients or people in the general population. By following ethical guidelines, a scientist develops a new drug or medical procedure without causing harm to a human subject. In this study, you will learn how to:



• explain the difference between in vitro and in vivo; • summarize the basic process of drug discovery; • describe the purpose and design of a clinical trial; • describe the features of an observational study; • explain the usefulness of a cohort.

In Vitro and In Vivo Observations can be made outside or inside a living thing. An observation can be made inside or outside a living thing. Special terms indicate how an experiment is done:

• in vitro: an experiment done outside a living thing, such as in a test tube or petri dish • in vivo: an experiment done inside a living thing, such as in a living cell or organism

In an in vitro experiment, a substance is observed in isolation after it has been removed from a living thing. For example, a scientist might separate an enzyme from all other components of a cell and observe it in a buffered solution. The opposite approach is to do an in vivo experiment, in which the same enzyme is observed while it is still inside a living cell. Misleading Results An in vitro experiment has advantages and disadvantages. The chief advantage of an in vitro experiment is that all variables are controlled; in other words, you know almost exactly what's happening in the test tube. The chief disadvantage of an in vitro experiment is that results can be misleading. For example, an enzyme might behave differently in a test tube than in a living cell. In a test tube, an enzyme is not influenced by substances it ordinarily would be if it were inside a cell. Yet because a living cell is crowded with molecules and organelles that could affect the activity of an enzyme, all in vitro observations must be confirmed in vivo. Drug Discovery Advances in human medicine depend on the discovery of new drugs. To treat a patient's disease or illness, a physician often prescribes a drug. A drug is a chemical substance that is used to treat or prevent disease. Many drugs are prescribed in the form of a pill. Drug discovery is the process by which a new drug is found and tested. It can be a difficult challenge, because drug discovery requires both in vitro and in vivo experiments. Drug Target The binding of a drug to its target is observed in vitro. A drug is typically a small molecule that binds to a larger molecule inside a living cell or organism. The larger molecule is referred to as the drug's target. A target molecule is something that is naturally produced by an organism or by a pathogen. For example, a target might be an enzyme that a virus makes after infecting a human cell. If the drug binds to this target, it might prevent the virus from causing a disease. In an in vitro experiment, the binding of a drug to its target is observed in a test tube. Important information is collected as follows:

• Does the drug actually bind to the target? • How strong is the drug-target interaction? • Do environmental conditions (temperature, pH) influence the interaction? • Does the drug affect the target's natural activity?

Testing a New Drug The physiological effect of a new drug is tested in vivo. To be useful, a drug must help cure a disease or relieve a medical condition. In an in vivo experiment, the effect of a drug on a living organism — especially on a human — is observed. Information is collected about the following key issues:

• Safety: Is it safe for a living organism to take the drug? • Dosage: How much of the drug must be taken?



• Efficacy: Is the drug an effective cure for a disease, or does it offer symptomatic relief? Drug discovery begins with in vitro observation, but the results must be confirmed in vivo. Sometimes, a drug binds to a target within a test tube in an in vitro experiment but does not bind to the target in a living cell or organism. Clinical Trial A clinical trial is an in vivo experiment that meets strict ethical guidelines. A clinical trial involves observation of an actual patient. Because an in vivo experiment involves a living subject, it is restricted by ethics. For example, a scientist cannot deliberately infect a human with a virus for the purpose of testing a new drug. This would be unethical, since the human would be exposed to unnecessary danger. To test a new drug or medical procedure, a scientist does a clinical trial. A clinical trial is a controlled experiment in which actual patients are observed and treated. The participants are volunteers who already have a particular disease or medical condition. Design of a Clinical Trial A clinical trial is a controlled experiment involving human subjects. The goal of a clinical trial is to do an in vivo experiment in a safe and ethical manner. Volunteer patients are gathered together in a hospital, where trained personnel are on hand to provide medical attention. The patients are informed about the potential risks and benefits of the experimental treatment and notified that they may withdraw from the trial at any time. The design of a clinical trial is similar to a controlled experiment because there are two groups:

• Experimental group: These patients receive the new drug or medical procedure. • Control group: These patients receive an old drug, placebo (fake pill), or earlier medical procedure.

The patients are not manipulated or interfered with, since their safety is more important than other concerns. Avoiding Bias Steps must be taken to avoid bias in a clinical trial. In a clinical trial, a scientist searches for patterns in the way patients respond to an experimental treatment. To ensure reliable results, a scientist must avoid unintentional bias. Bias is a preference that might unfairly influence the outcome of an experiment. For example, a scientist must not allow his or her own personal interests to affect the results. Bias is avoided by using the following techniques:

• Random assignment: Patients are randomly assigned to a group. • Double-blind testing: No one knows who receives treatment until afterward. • Large sample size: More patients are included to make patterns more obvious. • Having peer review: Scientists outside the study provide an independent evaluation.

The reliability of a clinical trial depends on its design and the avoidance of bias. Limitations of a Clinical Trial The usefulness of a clinical trial is limited by cost and size. A clinical trial involves costly medical attention. Because it is expensive to monitor patients continuously in a hospital, a clinical trial typically involves a small number of patients observed over a brief time period. However, this reduces the reliability of the results. For example, a clinical trial might indicate that a new drug is effective in 10 patients who were observed over one month. But how representative are these 10 patients? What if the patients are observed for longer than one month? In general, a clinical trial provides no evidence that a new drug or medical treatment will be effective in the general population or over an organism's entire life span. To solve these problems, a clinical trial is often combined with an observational study. Observational Study



An observational study is an in vivo experiment with uncontrolled variables. An observational study is a collection of data about the general population. An observational study is an experiment that involves data collection without any direct manipulation of subjects. For example, a scientist might observe the health of all people living within 100 miles of a nuclear power plant. The scientist might collect records on how often people in the group get sick or what diseases they develop. As a control, similar information would be collected for people who live farther away. In an observational study, a scientist is limited to observation only. No attempt is made to control variables or interfere with subjects. Instead, a scientist searches for patterns that emerge when the study group is compared to the general population. Cohort Study An observational study can be based on a cohort. A group of nuns could be a cohort in an observational study. To design an observational study, a scientist focuses on people who share a specific characteristic. This group is called a cohort. Smokers, for example, are a cohort. The following are characteristics used to make a cohort:

• Age: People born in the same year or the same decade • Geography: People who live in the same part of the world • Behavior: People who have the same habit or lifestyle • Occupation: People who have the same job or profession • Disease: People who suffer from the same disease or medical condition

By comparing a cohort to the general population, a pattern might be uncovered that indicates the significance of the shared characteristic. Once identified, it can be investigated with greater focus, beginning with an in vitro experiment. The Effects of Antibiotics How do antibiotics affect bacteria? To treat a patient, a physician needs to understand the human body. To develop a new drug, a scientist needs to identify a target molecule. Both types of medical research start with an in vitro experiment. If the in vitro experiments for a drug are successful, they are typically followed up with in vivo experiments. You will see how different types of antibiotics affect a variety of bacteria. In a lab titled "The Effects of Antibiotics," you will collect and classify bacteria, then design an experiment to determine how antibiotics affect bacteria. Because an in vitro experiment is done in a test tube or petri dish, you will be able to test how bacterial growth is affected by the presence of antibiotics.

STUDY GUIDE 5.4.1



QUIZ 5.4.2 1. Which of the following describes an in vitro experiment?

A. Observations are made in a plant. B. Observations are made in a test tube. C. Observations are made in a bacterium. D. Observations are made in a mouse.

2. Which of the following is an advantage of an in vitro experiment? A. Confusion is caused by the presence of many substances. B. Some enzymes behave unnaturally in a test tube. C. Cellular components interfere with observations. D. Variables and environmental conditions are controlled.

3. Which of the following is a reason for discovering a new drug? A. To replace a less-effective drug



B. To confuse patients and physicians C. To duplicate an older drug D. To create a new disease

4. Which of the following is required of a new drug? A. It must be easy to swallow. B. It must help cure a disease. C. It must be in liquid form. D. It must bind to a virus.

5. Why is a clinical trial restricted by ethics? A. It is costly and time-consuming. B. It can be performed in a petri dish. C. It is done in a test tube. D. It involves a human patient.

6. Where does a clinical trial usually take place? A. In a hospital B. In a test tube C. In a petri dish D. In a placebo

7. Which of the following is a limitation of a clinical trial? A. Number of test tubes B. Amount of peer review C. Amount of random assignment D. Hospital costs

8. What is unique about the experimental design of an observational study? A. Knowledge about a living thing is generated. B. Evidence is used to test a hypothesis. C. Data is collected and analyzed for patterns. D. Experimental subjects are left free of manipulation.

9. In a cohort study, a scientist collects health data on a group of nurses. What characteristic was used to form the cohort?

A. Geography B. Age C. Behavior D. Occupation

10. A scientist separates a specific protein from all other components of a yeast cell. Next, she searches for a small molecule that binds to the isolated protein. What type of experimental design is being used?

A. An occupational cohort study B. A clinical trial C. In vitro observation D. An age cohort study

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