Science unit 2 test on book

Life Science Biology — Multiple-Choice Questions

PART A

1. Homeostasis can be best described as

(1) the ability of living things to form groups in order to survive

(2) the process in which living things maintain stable internal conditions

(3) the changes that occur in the environment in which an organism lives

(4) the development of structures such as tissues, organs, and organ systems

2. Which situation is not an example of the maintenance of homeostasis in an organism?

(1) A runner perspires while running a race on a hot summer day.

(2) Specialized cells contribute to the regulation of water content in a geranium plant.

(3) The release of insulin lowers the blood sugar level in a human after eating a meal.

(4) Signals from nerves cause a person's muscles to contract so they can pick up an object.

3. Which of these best demonstrates an example of a positive feedback mechanism?

(1) One that causes body temperature to decrease when it is above a certain point

(2) One that causes blood sugar to increase when it is below a certain point

(3) One that causes hormone levels in the blood to continually increase during childbirth

(4) One that causes carbon dioxide levels to decrease once they reach levels that could be toxic

4. Which of these is an example of an effector in a feedback mechanism that maintains stable body temperature?

(1) Skeletal muscles that contract to produce heat

(2) Structures that detect temperature changes in the skin

(3) A structure in the brain that compares body temperature to a set point

(4) A change in the temperature of a room

5. Which of these statements best explains how guard cells help plants maintain homeostasis?

(1) Guard cells cause stomata to close when water levels are low.

(2) Guard cells store substances that can later be used by the plant.

(3) Guard cells produce nutrients that plants can use in times of stress.

(4) Guard cells send signals that cause other cells to decrease energy consumption.

PART B

Use the following information to answer question 6.

To survive, an organism must maintain the health of its cells. The normal internal environment of a human's cells would include a temperature of 37°C, a pH of 7, and a water/salt balance of 0.1 percent.

6. Which of the cells shown in the diagrams would belong to someone who is not maintaining homeostasis?

(1) Cell A

(2) Cell B

(3) Cell C

(4) Cell D

Questions 7–9

Use the following information to answer questions 7–9 based on the data in the following graph.

Graph: Body Temperature Over Time

The graph shows body temperature (°C) over 24 hours. It includes a range of homeostasis around 37°C and points labeled A, B, C, D, E, and F.

7. A disruption in homeostasis is indicated by the temperature change that occurs between points

(1) A and B

(2) B and C

(3) C and D

(4) E and F

8. Put these steps in order to show how a negative feedback mechanism in the body causes changes to return to normal after a disruption like the one shown in the graph.

a. effector causes change in body

b. sensors detect change in temperature

c. information is sent to body structures such as muscles

d. information is sent to a control center in the brain

(1) a, c, d, b

(2) d, b, c, a

(3) c, d, a, b

(4) b, d, c, a

9. The response that occurred in the body to bring body temperature back to a certain range after the disruption is an example of

(1) a positive feedback loop because it reversed the initial change

(2) a positive feedback loop because it increased the initial change

(3) a negative feedback loop because it reversed the initial change

(4) a negative feedback loop because it increased the initial change

Use the following graph to answer questions 10 and 11.

Graph: Internal Temperature and Skin Temperature

The graph compares internal temperature and skin temperature as environmental temperature increases from 20°C to 40°C.

10. The graph shows the effect of external (environmental) temperatures on a student's skin and internal temperature. Which statement best describes what happens as the environmental temperature increases?

(1) The skin temperature increases, then decreases to 20°C.

(2) The internal temperature increases abruptly to about 30°C.

(3) The skin temperature decreases to 30°C.

(4) The skin temperature increases, then levels off at about 36°C.

11. Which of these statements best explains why the student's internal temperature increases more slowly than the temperature of their skin?

(1) The skin absorbs excess heat, preventing heat from passing into the body.

(2) Feedback mechanisms cause body temperature to stay within a certain range.

(3) Organs on the inside of the body have cooling mechanisms, whereas the skin does not.

(4) Cells inside the body have structures that allow them to reflect heat, unlike cells on the outside of the body.

Use the information in the table to answer questions 12 and 13.

The graph shows data scientists collected when investigating how exercise affects breathing rate.

12. The graph shows data scientists collected when investigating how exercise affects breathing rate. Which of these statements best explains their results?

(1) Breathing rate increased because oxygen levels in the blood increased.

(2) Breathing rate decreased in order to deliver less oxygen to muscle cells.

(3) Breathing rate increased because carbon dioxide levels in the blood increased.

(4) Breathing rate decreased in order to allow oxygen to stay in the body for longer.

13. Which of these would help scientists understand how breathing rate is related to gas levels in the blood?

(1) Purchasing measurement tools that are less precise than those previously used

(2) Measuring carbon dioxide and oxygen levels in the blood instead of breathing rate

(3) Using sensors to quantify gas levels in the blood while measuring breathing rate

(4) Changing several variables in order to understand how each one affects breathing rate

PART A — Immune System

14. Why are killer T cells important to the immune system's ability to maintain homeostasis?

(1) They destroy the body's healthy cells that no longer divide properly.

(2) They kill infected body cells before the infection can spread.

(3) They prevent white blood cells from responding too quickly.

(4) They attack nutrients needed by viruses to reproduce.

15. White blood cells can prevent a serious infection by

(1) ingesting the harmful microbes

(2) filling the damaged tissues with pus

(3) repairing the skin after it has been cut

(4) constructing physical barriers against microbes

16. When the immune system detects an antigen, it

(1) produces antigens that cancel the effects of it

(2) destroys the antigen by cutting it in half

(3) pushes it out of the body immediately

(4) produces antibodies that bind to the antigen

17. A part of the hepatitis B virus can be synthesized in the laboratory. This viral particle can be identified by the immune system as a foreign substance, but the viral particle is not capable of causing the disease. After this viral particle is injected into a human, it

(1) triggers the formation of antibodies that protect against the hepatitis B virus

(2) stimulates the production of molecules that are able to digest the hepatitis B virus

(3) synthesizes specific hormones that provide immunity against the hepatitis B virus

(4) breaks down key receptor molecules so that the hepatitis B virus can enter body cells

18. Which of these is not a mechanism that prevents the development of a disease?

(1) Physical barriers such as the skin

(2) Inflammation that occurs after an injury

(3) Organ malfunction after exposure to pollutants

(4) Cells in the immune system such as memory B cells

19. Which of these best explains how a genetic disorder differs from infectious diseases?

(1) A genetic disorder cannot be inherited, but an infectious disease can be.

(2) A genetic disorder is inherited from one's parents, but an infectious disease is spread by close contact.

(3) A genetic disease is caused by exposure to microorganisms, but an infectious disease is not.

(4) A genetic disorder is caused by lifestyle choices such as diet and exercise, but an infectious disease is not.

20. Which of these is most likely to cause an improvement in a person's health?

(1) A job that exposes the person to a high number of toxins

(2) A job that causes the person to come into contact with pathogens

(3) A lifestyle change that causes the person to experience high levels of stress

(4) A lifestyle change that reduces the amount of alcohol the person consumes

21. A person develops an infection on their skin and goes to their doctor. The doctor concludes that the infection is caused by bacteria. Which of these is the doctor likely to recommend?

(1) An injection of a closely related type of live bacteria

(2) An antibiotic medication that reduces bacterial growth

(3) A vaccine made up of a weakened form of the bacteria

(4) A diet that reduces the amount of nutrients the person consumes

22. Some babies have allergic reactions to formula that contains cow's milk. Which of these most likely causes these babies to have an allergic reaction to this type of formula?

(1) The baby's immune system responds to bacteria present in the cow's milk.

(2) The baby's immune system recognizes the substances in the cow's milk as invaders.

(3) Viruses in the cow's milk cause the baby's immune system to become more active.

(4) The baby's immune system is weakened and not responding to substances in the cow's milk.

23. Which is the best procedure for determining if a vaccine for a disease in a particular bird species is effective?

(1) Vaccinate 100 birds, then expose all 100 birds to the disease.

(2) Vaccinate 100 birds and expose only 50 of them to the disease.

(3) Vaccinate 50 birds, and do not vaccinate 50 other birds; expose only the vaccinated birds to the disease.

(4) Vaccinate 50 birds, and do not vaccinate 50 other birds; expose all 100 birds to the disease.

24. Which of these best describes an autoimmune disorder?

(1) The immune system treats the body's own cells as invaders.

(2) The immune system overreacts to substances such as dust and pollen.

(3) The immune system is weakened and cannot adequately defend the body from disease.

(4) The immune system is unable to respond to bacterial infections due to a lack of phagocytes.

25. How does Acquired Immunodeficiency Syndrome (AIDS) affect a person's susceptibility to disease?

(1) It makes their immune system more active, which can cause organ failure.

(2) It makes their body produce too many white blood cells, which build up and cause disease.

(3) It strengthens their immune system so they cannot develop the disease a second time.

(4) It weakens their immune system so they have decreased defenses against disease.

PART B — Questions 26–29

Use the following information to answer questions 26 and 27 based on your knowledge of biology.

26. None of these volunteers ever had chicken pox. After the injection, the volunteer most likely would be antibodies to chicken pox in the bloodstream of

(1) Volunteers A and D only

(2) Volunteers A, B, and D

(3) Volunteer C only

(4) Volunteer D only

27. What is the purpose of injecting a person with a weakened chicken pox virus?

(1) To weaken their immune system so that it is prepared to accept the living chicken pox virus

(2) To prepare their immune system to react to other types of viruses, such as the mumps virus

(3) To help their immune system prepare for when it encounters the chicken pox virus again

(4) To ready their immune system for fighting viruses and bacteria using antibodies

28. The diagram below shows a type of white blood cell engulfing a bacterium. How does this process help maintain stability in the body?

(1) It prevents a serious bacterial infection from disrupting balance in the body.

(2) It prepares the body to deal with many different types of bacteria and viruses.

(3) It causes more bacteria to be produced, and the bacteria protect the immune system.

(4) It causes the immune activity in the body to decrease so that internal stability is not disrupted.

29. The following diagram represents one possible immune response that can occur in the human body. The structures that are part of the immune system are represented by

(1) A only

(2) A and C only

(3) B and C only

(4) A, B, and C

Life Science Biology — Multiple-Choice Questions (Continued)

Questions 1–5

1. A system that helps maintain homeostasis in the body is most likely to

(1) monitor conditions and adjust as needed

(2) allow changes only at scheduled times

(3) make changes only during major problems

(4) stop all changes from taking place

2. In an investigation to determine the change in heart rate with increased activity, a biology teacher asked students to take their pulses immediately before and immediately after exercising for 2 minutes. The data showed an average heart rate of 72 beats per minute before exercising and 90 beats per minute after exercising. If a valid conclusion is to be made from the results of this investigation, which assumption must be made?

(1) In most students, the average heart rate is not affected by exercise.

(2) Each student exercised with the same intensity.

(3) Exercise causes the heart rate to slow down.

(4) The heart rate of each student goes up 18 beats after jogging for 2 minutes.

3. A change in the body results in another change. This second change reverses the first change to maintain homeostasis. This describes a type of

(1) effector mechanism

(2) positive feedback loop

(3) negative feedback loop

(4) environmental stimulus

4. When a person does strenuous exercise, small blood vessels near the surface of the skin increase in diameter. This change is most likely related to the body's ability to

(1) produce new types of necessary molecules

(2) keep internal conditions within a preset range

(3) send and receive information to individual cells

(4) protect the body from substances present in the air

5. The diagram below shows how the body responds to changes in carbon dioxide levels in the blood.

CO₂ level in blood increases → Sensory structures detect change in CO₂ levels → Brain sends information to muscles in chest → Muscles in chest cause lungs to expand more rapidly → CO₂ level in blood decreases

This diagram is an example of

(1) coordinated responses that lead to lack of stability in the body

(2) structures working together to maintain homeostasis in an organism

(3) a homeostatic mechanism that helps deliver more carbon dioxide to cells

(4) a feedback mechanism that works to increase the initial change in the system

Questions 6–14

6. A disruption of homeostasis can result in all of the following except

(1) illness

(2) death

(3) disease

(4) stability

7. Infectious diseases result from

(1) genetic disorders

(2) pollutants

(3) pathogens

(4) organ malfunction

8. The inhalation of particles such as asbestos fibers and coal dust can result in diseases that affect the respiratory system. In such a case, the main cause of the disease would be

(1) microbes

(2) pollutants

(3) a genetic disorder

(4) organ malfunction

9. The body's main physical barrier against infection is

(1) the skin

(2) white blood cells

(3) red blood cells

(4) inflammation

10. Which activity would stimulate the human immune system to prepare for an invasion by a virus?

(1) being vaccinated against measles

(2) receiving antibiotic injections after surgery

(3) choosing a well-balanced diet and following it throughout life

(4) being exposed to high levels of pollutants that are toxic to cells

11. Antibodies are proteins that help the human immune system recognize and respond to particles that could harm the body. Which statement is least likely to describe antibodies?

(1) They may be produced in response to a certain substance.

(2) They may be produced in cells that are part of the immune system.

(3) They are produced in response to the presence of foreign substances.

(4) They are nonspecific, acting against any foreign substance in the body.

12. Which condition would most likely result in a human body being unable to defend itself against pathogens and cancerous cells?

(1) a genetic tendency toward a disorder such as diabetes

(2) the production of antibodies in response to an infection in the body

(3) a parasitic infestation of ringworm on the body

(4) the presence in the body of the virus that causes AIDS

13. When an overactive immune system starts to attack its own body tissues, it causes serious conditions known as

(1) antihistamine diseases

(2) allergic reaction diseases

(3) autoimmune diseases

(4) immunodeficiency diseases

14. One purpose of increased breathing rate when a person is exercising is to

(1) prevent body cells from obtaining oxygen

(2) decrease levels of waste gases in the blood stream

(3) ensure that levels of wastes in the blood increase over time

(4) keep cells from expelling wastes so that the waste molecules can be reused

Questions 15–18

Use the diagram below, which shows how the pancreas produces substances in response to changes in blood glucose (sugar) levels, to answer questions 15 and 16.

Diagram sequence:

Ingestion of starch → Elevated blood sugar levels → Secretion of insulin is increased → Drop in blood sugar levels → Secretion of insulin is decreased

15. According to the diagram, when is insulin likely to be secreted?

(1) when a person has not eaten for a long time

(2) when blood glucose levels are within normal levels

(3) soon after a person eats a meal

(4) when insulin levels in the blood are high

16. The mechanism that causes blood sugar to return to a set level after an initial increase is an example of

(1) a positive feedback loop that ensures that blood sugar continues to increase

(2) a negative feedback loop that amplifies the initial change in the system

(3) a positive feedback loop that brings about a rapid decrease in blood sugar

(4) a negative feedback loop that causes blood sugar to decrease after the change

17. Which graph of blood sugar levels over a 12-hour period best illustrates the concept of feedback mechanisms maintaining homeostasis in the body?

(1) Graph showing large, irregular fluctuations in blood sugar levels

(2) Graph showing small, repeated fluctuations around a relatively stable level

(3) Graph showing blood sugar levels continually increasing

(4) Graph showing blood sugar levels continually decreasing

18. When carbon dioxide levels in the blood are above the normal set point, which of these is likely to occur?

(1) The diaphragm will relax in order to slow the flow of air into the body.

(2) The diaphragm will contract more slowly to increase the amount of carbon dioxide that stays in the body.

(3) The diaphragm will relax in order to move oxygen from cells into the lungs.

(4) The diaphragm will contract more quickly to move carbon dioxide out of the body.

Questions 19–23

19. In the feedback mechanism that helps maintain normal carbon dioxide levels in the blood, the diaphragm is an example of a(n)

(1) stimulus

(2) effector

(3) sensor

(4) control center

Refer to the following list, which describes three ways of controlling viral diseases in humans, to answer question 20.

• Administer a vaccine containing dead or weakened viruses, which stimulates the body to form antibodies against the virus.

• Use chemotherapy (chemical agents) to kill viruses, similar to the way in which sulfa drugs or antibiotics act against bacteria.

20. Based on this information, which activity would provide the greatest protection against viruses?

(1) producing a vaccine that is effective against interferon

(2) using interferon to treat a number of diseases caused by bacteria

(3) developing a method to stimulate the production of interferon in cells

(4) synthesizing a drug that prevents the destruction of bacteria by viruses

Base your answers to questions 21–23 on the table below, which shows a portion of the results of a study designed to investigate the effectiveness of an antibiotic treatment. Some participants received an antibiotic medication, and some received a sugar pill (placebo), which contains no active ingredient.

21. The antibiotic treatment that some participants received in this study was most likely designed to treat

(1) a genetic disorder

(2) a bacterial infection

(3) a disease caused by a virus

(4) organ failure caused by injury

22. What do these data show about the effectiveness of this treatment?

(1) It reduced symptoms in some participants.

(2) It reduced symptoms in all study participants.

(3) It was equally as effective as the placebo at reducing symptoms.

(4) It was not as effective as the placebo was at reducing symptoms.

23. Which of these is most likely to help investigators better understand how this treatment reduces symptoms in study participants?

(1) reducing the number of participants involved in the study

(2) involving more participants, especially those with diverse backgrounds, in the study

(3) removing regulations that require researchers record side effects reported by participants

(4) conducting studies that do not adhere to ethical guidelines for conducting studies on humans