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Life Science A Unit 2 Answer Key: Asexual vs. Sexual Reproduction Name _________________________________________ Date____________________________ Objective In this activity, you will observe and describe the variations in reproductive patterns of organisms, including asexual and sexual reproduction. Activity There are two principal modes of reproduction, asexual and sexual. Asexual reproduction requires one parent. Forms of asexual reproduction include binary fission, budding, and fragmentation. Sexual reproduction requires two parents. There are advantages and disadvantages to each form of reproduction. Asexual means “without sex” in the Greek language. Asexual reproduction uses mitosis to create a new individual in which all of its genes come from one parent without the fusion of sperm and egg. Some organisms that use asexual reproduction include bacteria, hydra, and starfish. A bacterium consists of circular DNA and proteins. In binary fission, a bacterium goes through these steps: 1. Replication of its chromosomes (DNA). 2. A copy of chromosomes moves to one end of the cell; the original chromosomes move to the other end. 3. The plasma membrane grows inward; the cell wall deposits itself. 4. Two daughter cells results. A hydra is a multi-cellular organism that reproduces by budding. Budding is a mitotic process in which the parent produces a mass or a bud of cells. This bud of cells is an exact copy or clone of the parent. Eventually the bud separates from the parent and forms a new hydra. A starfish reproduces by fragmentation. In the fragmentation process, the starfish body is broken into several pieces. Some or all of these pieces will develop into a new organism. Fragmentation must be accompanied by regeneration. Regeneration is not asexual reproduction. It is the regrowth of body parts that have been lost. Sexual reproduction is the creation of offspring(s) by the union of a female gamete (ovum) and a male gamete (spermatozoon). These two haploid cells fuse together to form a zygote. Haploid means that it has “half” of the normal amount of chromosomes for that species. Humans have 46 chromosomes. A female gamete has 23 chromosomes, and a male gamete has 23 chromosomes. Most multi-cellular organisms use sexual reproduction to create offspring. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 There are some potential advantages for each type of reproduction. These advantages may be specific to organisms. They may ensure the longevity of a species. On the other hand, they could mean the demise of a species. Asexual reproduction has several advantages. It can produce numerous offspring in a short time. If an organism lives in an isolated place, it can still reproduce without a mate. The offspring is an identical copy of the parent, which could be beneficial. Sexual reproduction has several advantages that we see every day. Sexual reproduction gives rise to offspring that have a combination of both parents, thus more variety. By combining genetic material from both parents, there is a chance to minimize or avoid the genes for deadly disorders from one parent. This genetic variation occurs mainly during meiosis and fertilization. 1. Place a check under the correct form of reproduction. Feature One parent Two parents Bacteria Humans Starfish Cats Hydra Dogs Asexual 9 Sexual 9 9 9 9 9 9 9 2. What are the three forms of asexual reproduction mentioned? What form of reproduction requires the assistance of regeneration? Binary fission, budding, and fragmentation. Fragmentation requires the process of _____________________________________________________________________________ regeneration to create a new organism. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2 3. List the advantages for each form of reproduction. Asexual: 1. no need for a mate ____________________________________________________________________________ 2.____________________________________________________________________________ produce numerous offspring in a short time 3.____________________________________________________________________________ a clone of a parent Sexual: 1.____________________________________________________________________________ provides a diverse offspring 2.____________________________________________________________________________ can mask or hide deadly genes 4. In this exercise, you will create an original organism by budding. In the first box, draw an imaginary organism about the size of a quarter, this is the parent. Draw the exact same organism but much smaller, and it must be attached to the parent organism. This smaller version is the offspring that is budding. In the second box, draw the parent and the offspring unattached. You have created an offspring by budding. Parent with offspring attached Parent and offspring unattached Images will vary. The first image should be a parent with the offspring attached. The second image should be the parent and the offspring unattached. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 3 Life Science A Unit 2 Answer Key: Sickle Cell Anemia Name _________________________________________ Date____________________________ Objective In this activity, you will learn the importance of iron in red blood cells and how free iron may cause organ damage, especially for those who suffer from sickle cell anemia. Activities Oxygen is necessary for human life. With each breath, oxygen is exchanged for carbon dioxide in our lungs. The oxygen attaches to our red blood cells and is carried throughout the body. Hemoglobin is the component in red blood cells that carries oxygen. Oxygen attaches to iron found in hemoglobin. The prefix “heme” means iron, and the presence of oxygen and iron gives our blood cells their red color. Without iron, oxygen could not be transported through the body. Individuals with low amounts of iron attached to their red blood cells are referred to as anemic. Anemia may be caused by many different factors. Sickle cell anemia is an inherited blood disease that is characterized by defective hemoglobin. Red blood cells sickle because of a genetic defect that occurs in individuals with this disease. It is caused by a genetic mutation in the coding of an amino acid needed to form healthy blood cells. There are several interesting facts about sickle cell anemia. First, sickle cell anemia only affects individuals that live in or are descendants of equatorial countries; second, individuals with sickle cell or who carry the trait cannot contract malaria. (The amino acid that is mutated is the site malaria needs to infest human blood.) Finally, the mosquitoes that carry malaria (a disease caused by parasites that affects red blood cells) are only found in equatorial regions. Individuals develop sickle cell when the trait is passed to them by both parents. If only one parent passes the trait, the person is considered a carrier. A carrier does not have sickle cell but could pass it to his or her children. Normal red blood cells are round and smooth. They are designed to move easily through blood vessels. When red blood cells become shaped like a sickle or scythe, they become stiff. These cells cannot move as easily through the blood stream. Because of the odd shape of the cells, they tend to clump and clog the blood vessels. When this occurs, the blood that is carrying oxygen cannot reach its destination. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 Normal blood cells Normal red blood cells and a sickled cell When cells sickle, blocking blood vessels and causing anemia, the individual suffering with the condition is said to be in crisis. After several crises, red blood cells decrease their ability to carry oxygen. The spleen (an organ responsible for blood storage and the destruction of old blood cells) may shut down in a severe crisis. A sickle crisis causes extreme pain, swelling of the toes and fingers, and possible death of the tissue where oxygen could not reach. One extremely dangerous effect of sickle cell anemia is pooling. Pooling is when the sickle cells pool, or collect, in the spleen. This causes a sudden drop in the hemoglobin. When a cell sickles, it also loses iron. Although iron is needed within hemoglobin to transport oxygen, large amounts of free iron (not attached to the hemoglobin) is poisonous to the body and may damage internal organs. The same iron needed to carry life-giving oxygen can cause organ damage and lead to death if the amount is out of balance with what the body needs. It is suggested that sickle cell patients take vitamins rich in folic acid to recover from a crisis quickly. Folic acid helps the body produce red blood cells at a faster rate. Some researchers believe that children with sickle cell need about 20% more calories than other children. This increase in calories is needed to fuel the production of red blood cells and to replace the damaged, sickled cells. 1. What group of people tends to have the trait for or carry sickle cell anemia? People who live in or who are descendants of equatorial regions. ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2 2. What can a person with sickle cell do to recover from a crisis quickly? Take vitamins that are rich in folic acid. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 3. Why do sickled red blood cells cause so many problems? Sickled red blood cells get stuck and clump in the blood vessels. When this occurs, there is pain, _____________________________________________________________________________ swelling, anemia, and possible pooling. The red blood cells can not deliver oxygen to the body. _____________________________________________________________________________ The cells can also release iron, causing the organs to receive heavy metal poisoning. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 4. If a child receives the gene mutation that causes sickle cell from one parent, will the child have the disease? What if the mutation is received from both parents? No. If the child receives the trait from one parent, the child will be referred to as a carrier, or _____________________________________________________________________________ someone who can pass on the disease. If both parents pass the trait on to the child, the child will _____________________________________________________________________________ have sickle cell anemia. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 3 Life Science A Unit 2 Answer Key: Life Is in the Blood Name _________________________________________ Date____________________________ Objective In this activity, you will learn about the importance of blood donation. Link American Red Cross http://www.pleasegiveblood.org/education/about_blood.php Activities Blood donations save millions of lives each year. Giving blood is a simple way to save the life of someone in your community. Access http://www.pleasegiveblood.org/education/about_blood.php and read the following sections: All About Blood, Blood Types; How Blood is Tested, How Blood is Processed, and FAQs to find out about the different products that are made from blood, how all human blood is alike and different, how blood is processed, and much more. 1. What are the two most common blood types in the United States? a. O-positive and B-positive b. O-negative and A-positive c. O-positive and A-positive d. B-positive and A-negative 2. What are the four components that can be derived from a unit of blood? a. AHF, white blood cells, red blood cells, and hemoglobin b. AHF, platelets, red blood cells, and hemoglobin c. platelets, white blood cells, albumin, and plasma d. red blood cells, platelets, AHF, and plasma Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 3. Where are red blood cells manufactured? a. in the heart b. in the spleen c. in bone marrow d. in joints 4. Is it possible to contract HIV by donating blood? Explain your answer. _____________________________________________________________________________ No. HIV and other transmissible viruses cannot be contracted through blood donation. The _____________________________________________________________________________ equipment used is sterile and used only once then immediately discarded, and a new needle is _____________________________________________________________________________ used for each donation. _____________________________________________________________________________ _____________________________________________________________________________ 5. What is a Universal Donor? Explain why. A person who has type O blood is a universal donor because his or her red blood cells may be ____________________________________________________________________________ transfused to patients of any other blood type in an emergency situation or if the needed blood ____________________________________________________________________________ type is unavailable. ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2 Life Science A Unit 2 Answer Key: Feedback Mechanisms Name _________________________________________ Date____________________________ Objective In this activity, you will learn about feedback mechanisms with a system that serves to keep changes within a specified limit. Activities Human beings are complex organisms. There are millions of functions that are occurring simultaneously inside the human body. Many of these functions are self-regulating. In a selfregulating process, the product of the process regulates the process. One of the most important processes is to maintain stability, homeostasis, in an ever-changing external environment. The human body carries out this regulatory process through feedback mechanisms. Some of the functions of feedback include regulating cellular respiration, body temperature, chemical reactions, and blood clotting. Feedback mechanisms are considered positive or negative. Positive feedback speeds up or amplifies a change in the human body. One example of positive feedback is human blood clotting. The blood vessels become injured, and the platelets release chemicals. These chemicals attract more platelets, and they begin to clump together. Eventually, the platelets stick together to seal the wound. Positive feedback is less common than negative feedback in the human body. Negative feedback slows down or stops a process. This mechanism prevents small changes from becoming too large. One negative feedback mechanism is cellular respiration. It is the most common way for a cell to make energy or ATP. Cellular respiration consists of an anabolic pathway (electron transport chain) and a catabolic pathway (glycolysis and Kreb cycle). During the anabolic pathway, complex molecules are synthesized, or made from, simpler molecules. During the catabolic pathway, complex molecules are broken down, and energy is released. Cellular respiration involves glycolysis, the Kreb cycle, and the electron transport chain. Glycolysis takes place in the cytosol of the cell and begins the breakdown of glucose (sugar). The Kreb cycle, which takes place in the mitochondrial matrix, finishes the job by breaking down pyruvate into carbon dioxide. The carbon dioxide represents remnants of organic molecules. The third step, the electron transport chain, uses electrons from the Kreb cycle and combines them with hydrogen and oxygen to make water. Certain enzymes set the pace for cellular respiration. They contain receptor sites that are specific for inhibitors or activators. For example, if there is an abundance of ATP, the cell slows down making a certain enzyme used in glycolysis. Once ATP is low, the cell will activate the enzyme and speed up glycolysis. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 If you are exercising, there is a need for more energy in the muscle cells. The cells that do not need energy immediately will slow down or stop making ATP. The enzymes will start, stop, or slow down cellular respiration at different steps in the process. To sum it up, glycolysis changes glucose to pyruvate and produces a little energy, ATP. The Kreb cycle takes the pyruvate and combines it with another compound to form electrons the electron transport chain can use. The Kreb cycle produces a little energy and some electrons. The electron transport chain makes the bulk of the energy for cells. 1. What are the two types of feedback mechanisms, and how do they differ? Positive feedback speeds up or amplifies a change in the human body. Negative feedback _____________________________________________________________________________ slows down or stops a process. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 2. Thermoregulation is the body’s ability to regulate its internal temperature. As a human, your optimal internal temperature is 98.6° F. Imagine going outside, and it is 105° F. You are dressed in a heavy coat, boots, snow pants, gloves, and a hat. This clothing is going to increase your internal body temperature. What are some of the symptoms that your body is trying to regulate itself when it is extremely hot outside? How can you help your body cool down even faster? Your body wants and needs to cool down internally. It will sweat and breathe harder to cool _____________________________________________________________________________ down. You can remove the excess clothing to quickly lower the stress on the body. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2 3. Positive feedback is not as common as negative feedback in humans. What is the example of positive feedback from the passage above? Why is this example so important to humans? One example of positive feedback is the human blood clotting. The blood vessels become _____________________________________________________________________________ injured, and the platelets release chemicals. These chemicals attract more platelets, and they _____________________________________________________________________________ begin to clump together. Eventually, the platelets stick together to seal the wound. It is _____________________________________________________________________________ important that this function happens fast. If not, a person could go into shock or bleed to death. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 4. What are the three parts of cellular respiration? How much energy does each component make? The three parts of cellular respiration are glycolysis, Kreb cycle, and electron transport chain. _____________________________________________________________________________ Glycolysis makes a little energy. The Kreb cycle makes a little energy for cells. The electron _____________________________________________________________________________ transport chain makes the bulk of the energy for the cells, thus for the entire body. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 3 Life Science A Unit 2 Answer Key: Growing Hair Name _________________________________________ Date____________________________ Objective In this activity, you will illustrate how hair grows too slowly to be observed with the naked eye. Activity Read the passage below. Then, answer the questions that follow. Some processes happen too slowly on too small of a scale to be observed by the naked eye. We know that they are occurring, but how can it be proven? Let’s discuss human hair. We know that it grows naturally. This growth can be measured by the length and diameter of the hair. We know that we shed hair. We have hair on our heads, and we have hair on our bodies, which is called body hair. Although body hair and hair on your head grow to different lengths, they go through the same growth process. Hair has a life cycle. This life cycle has three phases—active, transitional, and resting. During the active, or anagen, phase, there is protein synthesis and hair growth. During the transitional phase, the hair growth slows down until it stops. This takes about two weeks. The last phase is the resting, or telogen, phase. The old hair comes out of the hair follicle, and the new hair replaces it. Body hair and hair on the head grow at different rates. Body hair grows less than 1/3 of a millimeter per day. Hair on your head grows approximately 1/2 of a millimeter per day. Here is what we know: • • • • • Hair grows fastest in the summer. Hair grows slowest in the winter. Hair growth is the best between the ages of 15 and 30. Hair growth slows down between the ages of 40 and 50. Adults begin to lose hair around the age of 50. If scientists know that hair grows although we can not see it, how is it measured? Scientists use optical microscopy and image analysis to measure hair growth. Optical microscopy is the use of a specialized microscope attached to computers. The hair is removed from the scalp and placed on a glass slide to be viewed on the microscope. Digital image analysis is the use of computer software to view the image of the hair follicle from the microscope. The digital imaging software can also measure the hair. By combining these two things, scientists are able to accurately measure hair growth and, in particular, hair length. The hair diameter, or thickness, is negligible, making it nearly impossible to measure. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 Based on this information, answer the following questions. 1. You have been asked to volunteer in a clinical trial for a hair growth product. It is hypothesized that your hair will grow two centimeters per day. First you must shave your head, and then apply the hair product to your scalp. You set the timer and wait 24 hours. After 24 hours, you shave your head again and place a strand of hair on a glass slide. What should you do next? Put the glass slide under a microscope and look at it. Save the image on the computer. _____________________________________________________________________________ Measure its length to see if it is two centimeters. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 2. On average, how fast does hair grow? Hair on one’s head grows about 1/2 mm per day. Body hair grows approximately a 1/3 of a ____________________________________________________________________________ millimeter a day. ____________________________________________________________________________ 3. What are the three phases of hair growth? The three phases are active (anagen), transitional, and resting (telogen). _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2 4. When does hair grow the fastest and the slowest? Hair grows the fastest in the summer and the slowest in the winter. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 5. The longest hair known to be grown by a human is 5.6 meters. Knowing this, how many days do you think it took for the hair to grow that long? Here is a hint: Hair grows 1/2 millimeter per day, which equals 0.0005 m. 5.6 meters ÷ 0.0005 meters per day = 11,200 days _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 3 Life Science A Unit 2 Answer Key: Effects of Drugs on Enzymes Name _________________________________________ Date____________________________ Objective In this activity, you will describe how factors such as radiation, ultraviolet light, and drugs can alter cellular structure or function. Activity Most chemical reactions in the body can be described using the lock and key theory. This theory states that a substrate, or substance that needs to be changed, has the same shape of the enzyme (lock) and fits within the active site of the enzyme like a key. Functions, including those that occur on the cellular level, are regulated by the body using this type of mechanism. Although cellular functions are regulated by the body, in most cases they can be changed by external factors. These factors include radiation, ultraviolet light, and the use of drugs. The focus of this activity is the effect of drugs on the active sites of enzymes. Enzymes are proteins that catalyze, or speed up, chemical reactions. Reactions are increased by lowering the activation energy. In some cases, reactions need to be hindered, especially those that are caused by cells that reproduce uncontrollably. When cells reproduce at an uncontrollable rate, the term used to describe those cells is cancer. In other cases, the use of drugs can block or inhibit the active site of a reaction. Enzymes are not altered in a chemical reaction, so they can be reused repeatedly. An example of the lock and key theory is shown below. The enzyme has an active site where the substrate (reactants) bonds. The enzyme may adapt to improve the fit with the substrate. The enzyme forms a bond with the product. Eventually, the products are formed, and the enzyme returns to its original form. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 When an active site is blocked directly by another substance and the reaction does not occur, it is called competitive inhibition. When a site other than the active site is filled with an inhibitor and the reaction can not take place, it is called noncompetitive inhibition. Many drugs block the natural reactions that occur in the body either by causing another reaction to occur (competitive inhibition) or just by blocking the active site (inhibition) and not allowing any reaction to occur. Many drugs target enzymes at signaling points. From the table below, you can see the purpose and possible side effects of several classes of drugs. Drug type Example Purpose/ Function Side Effect(s) Psycho stimulants Amphetamine Increase awareness and arouse pleasure centers Dizziness, blurred vision, addiction Opiates Morphine Suppress response to pain Can become addictive as well as suppress vital body functions (ex. heart) Nicotine Tobacco Mild stimulant Addictive and may cause cancer All of these drugs affect the targeted enzyme at the active site or the inhibitor site, depending on whether it is competitive or noncompetitive. The drugs block the site, and other reactions that need to occur within the body are blocked. This interference can cause permanent damage within the cells and the entire body. Use this information to answer the following questions. Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2 1. Name three things that can alter cellular function. radiation, ultraviolet light, and drugs _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 2. How does an enzyme affect a chemical reaction? An enzyme speeds up a chemical reaction by lowering its activation energy. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 3. What are some of the side effects from using drugs that interfere with cellular function? Use the table provided. drug addiction, blurred vision, cancer, heart failure, etc. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 3 4. Match the following terms. d ______ enzyme a. an inhibitor attaches to the active site e ______ active site b. a reactant b ______ substrate c. an inhibitor attaches to a site other than the active site d. a protein that speeds up a reaction f ______ opiate a ______ competitive e. location where the substrate attaches to the enzyme c ______ noncompetitive f. a drug that suppresses response to pain Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 4 Life Science A Unit 2 Answer Key: Cell Division Name _________________________________________ Date____________________________ Objective In this activity, you will learn about prokaryotic and eukaryotic cell division. Link Cell Division: Binary Fission and Mitosis http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookmito.html Mitosis http://www.contexo.info/DNA_Basics/Mitosis.htm Activity The cell is the basic unit of life. All living cells can be divided into two groups: prokaryotic and eukaryotic. Animals, plants, fungi, protozoans, and algae all possess eukaryotic cell types. Only bacteria have prokaryotic cell types. Access http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookmito.html to learn about how prokaryotic and eukaryotic divide and then answer the questions that follow. 1. What features do prokaryotic and eukaryotic cells have in common in their cell division process? Replication of the DNA in both prokaryotic and eukaryotic cells must occur. The cell is first ______________________________________________________________________________ segregated and then replicated. Cytokinesis, the process where one cell splits off from its sister ______________________________________________________________________________ cell, ends this cell division process. ______________________________________________________________________________ ______________________________________________________________________________ 2. How are prokaryotic and eukaryotic cells different? Prokaryotic cells are much simpler in their organization than eukaryotic cells. They also have ______________________________________________________________________________ many more organelles and chromosomes. ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 1 3. What is the usual method of prokaryotic cell division called? binary fission ______________________________________________________________________________ 4. Define binary fission. Binary fission is the method by which a cell reproduces. It is a form of asexual reproduction in _____________________________________________________________________________ which a cell divides into two “sister” cells after DNA replication. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 5. Briefly describe how prokaryotic cells divide. The prokaryotic cell first replicates, and then it attaches the new copy to a different part of the cell ______________________________________________________________________________ membrane. When the cell begins to pull apart, the replicated cell and original cell are separated. ______________________________________________________________________________ After this process, there are two cells of identical genetic composition. ______________________________________________________________________________ ______________________________________________________________________________ 6. During mitosis, if the parent cell has 46 chromosomes, then the daughter cell should end up with 46 chromosomes. _____ Access http://www.contexo.info/DNA_Basics/Mitosis.htm to learn about the different phases of cell division during mitosis and then answer the questions that follow. 7. In which stage of mitosis do all of the chromosomes line up across the center of the cell? metaphase ______________________________________________________________________________ 8. In which phase do the chromosomes coil and become short and thick? prophase ______________________________________________________________________________ 9. In which phase do the chromosomes separate? anaphase ______________________________________________________________________________ 10. In which phase does a new nuclear membrane form in each daughter cell? telophase ______________________________________________________________________________ Copyright © 2006 PLATO Learning, Inc. All rights reserved. PLATO® is a registered trademark of PLATO Learning, Inc. Straight Curve, Academic Systems, and PLATO Learning are trademarks of PLATO Learning, Inc. PLATO, Inc. is a PLATO Learning, Inc. company. 2