HESI A2 Biology Study Guide

HESI A2 Biology Study Guide   HESI A2 Biology Study Guide Cellular respiration Cellular respiration is the process inside of cells that converts nutrients (such as sugars, amino acids, and fatty acids) into ATP (adenosine triphosphate), which is used throughout the organism for energy. Large molecules are broken into smaller molecules, which releases both energy and waste. Aerobic respiration occurs in the presence of Oxygen and has four main stages: • Glycolysis: Larger sugar molecule is broken down into 2 smaller sugar molecules in the cytoplasm. Net gain of 2 ATP and 2 NADH • Formation of Acetyl CoA: Pyruvate undergoes oxidative decarboxylation to form Acetyl coenzyme A. 1 CO2 is released as waste. Net gain of 2 NADH. • Citric acid cycle: also known as Krebs cycle. The 2 small sugar molecules produced during glycolysis are oxidized forming new products. Gain of 2 ATP, 6 NADH, 2 FADH2. • Electron transport chain: redox reaction involving the electrons removed during glycolysis and the Krebs cycle. Protons are pumped across the mitochondrial membrane to form a gradient, which drives the synthesis of 34 ATP. Anaerobic respiration is a type of cellular respiration which occurs when oxygen is not present. This process is most commonly performed by bacteria and Achaea. These organisms use this process to obtain energy because they live in environments with low oxygen levels. Example: Achaea called methanogens use carbon dioxide to accept electrons. Methanogens can be found in soil and the digestive systems of animals called ruminants, which includes cows and sheep. Anaerobic respiration, similar to aerobic cellular respiration, uses electrons from the fuel molecules to pass through the electron transport chain, which drives ATP synthesis. The electron transport chain moves electrons to create a proton gradient that allows for the synthesis of ATP. Electron transport chains are used for extracting energy. This can happen in plants, where the energy from the sunlight is used to create glucose and oxygen through photosynthesis in the chloroplast. Eukaryotes perform this process in the mitochondria. Fermentation is another type of cellular respiration which occurs in the absence of Oxygen. Organisms capable of fermentation include prokaryotes, yeast, and multicellular organisms such as humans. Feature Aerobic Respiration Anaerobic Respiration Oxygen requirement Yes, always No, never Waste products Carbon dioxide and water Carbon dioxide and ethanol Efficiency in releasing energy from glucose Very efficient (most of the energy is released from glucose) Less efficient (some energy locked in ethanol is not released) Some energy released as heat Yes Yes, but less than that for aerobic respiration Antibiotics Antibiotics are a kind of medicine used to treat bacterial infections. Not all bacteria are bad or unhealthy. Humans and other animals actually have a healthy ecosystem of bacteria, called normal flora. These are the good kind of bacteria. Pathogenic bacteria are the type which can cause infection. Some bacteria will cause infection no matter where they are, but others are safe in some areas of the body, but become infectious when they wander to a new location in the body. An example of this is if the bacteria in the gut, or intestines, were to try and live in the bladder or another organ. This is what happens in case of a urinary tract infection. The body’s immune system must try to fight and destroy the invading bacteria. Antibiotics are chemicals that enter and stick to certain parts of the bacterial cell. The parts where the antibiotics can attach can be the proteins/sugars in the bacterial cell wall or the important enzymes that make new bacterial DNA or proteins. This act of blocking these parts interferes with the bacteria’s ability to survive and multiply. If the correct antibiotic is used, the bacteria will stop growing or die. Without antibiotics, bacteria can grow and multiply, especially if the immune system cannot battle the bacteria. If enough antibiotic is present, the bacterial cell is crippled and stops growing, known as bacteriostatic, or it simply dies, known as the bactericidal effect. Antibiotics do not affect viruses, fungi or parasites as they bind only to bacterial cell targets. Some bacteria have the ability to become antibiotic resistant. This happens when bacteria have overexposure to antibiotics. The bacteria no longer are affected by the antibiotic because it undergoes mutations. Cells and tissues The basic building block of the body is the cell. Cells can perform a wide variety of functions, depending on the specialized type of cell that it is. Every type of cell plays a vital role in growth, development, and maintenance of the body. Cells from all organisms, ranging from humans to plants to bacteria, share certain characteristics. There are two categories that cells fall into: prokaryotic and eukaryotic. Prokaryotic cells are single-celled organisms from the domains Bacteria and Archaea. “Pro-” means before and “kary-” means nucleus, hence prokaryotic cells lack a nucleus and other membrane-bound organelles. Eukaryotes are made of two or more cells. “Eu-” means true, which means that eukaryotic cells have a nucleus. All types of cells share four key components: plasma membrane, cytoplasm, DNA and ribosomes. Prokaryotic cells have DNA, but it is not housed in a nucleus. The majority of the DNA in prokaryotic cells is found in a central region of the cell called the nucleoid. Bacteria are a specific type of prokaryotic cell. Most bacteria are surrounded by a rigid cell wall, which provides an extra layer of protection, helps the cell maintain its shape and prevent dehydration. Many bacteria have an outermost capsule that is sticky and helps the cell attach to its surroundings. Some bacteria also have a flagellum. It is a whip-like structure that acts like a motor to help the bacteria to move. Fimbriae are hair-like structures that are used to attach to other surfaces or host cells. Sometimes bacteria have pili, which allows the cell to transfer DNA to other bacteria or helps with locomotion (movement). Eukaryotic cells are significantly more complex compared to prokaryotic cells. They contain a variety of different compartments that have specialized functions, and are separated by layers of membrane. This organization allows each compartment to maintain its respective conditions and do what it needs to carry out its job. These compartments are called organelles. Unlike prokaryotic cells, eukaryotic cells have a nucleus, membrane-bound organelles, and multiple linear chromosomes. Eukaryotic cells have an array of organelles that are important for energy balance, metabolism, and gene expression. Difference between plant and animal cells: Plants Animals Cellulose cell wall surrounds the cell membrane Cell wall is absent in animal cells Plastids are present – especially a green pigment called chlorophyll Chlorophyll is absent in animal cells Large vacuoles containing cell sap are present in plant cells Vacuoles are usually absent Most plants do not exhibit movement of locomotion Most animals exhibit movement of locomotion Keep growing throughout their life and are localized in the apical meristem Growth stops after maturation but body cells are replaced periodically. Growth is uniform and proportionate. Manufacture their own food by photosynthesis Cannot make their own food. They depend directly or indirectly in plants for their food Sense organs and nervous system absent Well-developed nervous system Cells make up tissues. Tissues make up organs. Multiple organs make up organ systems, which make up organisms. There are four basic types of tissue: epithelial, connective, muscle, and nervous. Types of cells in tissues: Cells Functions Muscle cells These are usually cylindrical or spindle-shaped. They cause some parts of the body to move by contracting. Epithelial cells They form a layer and protect the cells below them from injury. Red blood cells These cells which are shaped like disco do not have nucleus. They bring oxygen to different parts of the body. White blood cells These cells have a nucleus. They can change their shape. They kill or engulf microorganisms such as bacteria which enter the blood stream. Nerve cells These cells are very long. They carry information (impulse) from one part of the body to another. Sperm This cell has a long tail which helps it to move about. It can unite with an egg cell (ovum) to form a baby. Ovum (egg cell) This is the largest cell in woman’s body. It does not move on its own. It develops into a baby if its united with a sperm. Epithelial tissue consists of tightly packed layers of cells that cover surfaces and line body cavities. This includes skin and intestine lining. Since these cells are tightly packed, they act as barriers to the movement of fluids and harmful invaders. Epithelial cells are special because they are polarized. This means that they have a top and bottom side. The top side is called the apical side and it faces the inside of the cavity or the outside of a structure and is usually exposed to fluid or air. The bottom side is called the basal side. This faces underlying cells. The diagram to the right shows intestinal cells. Connective tissue consists of cells suspended in an extracellular matrix. This matrix is typically made up of protein fibers like collagen and fibrin in a solid, liquid, or jelly like substances. Connective tissue supports and connects other tissues. Loose connective tissue is the most common type and supports organs and blood vessels. Dense, or fibrous, connective tissue makes up tendons and ligaments to connect muscles and bones. Muscle tissue keeps the body upright and allows for movement. Skeletal muscle makes up the muscles of movement and contract and relax voluntarily. Smooth muscle tissue is found in organs, like the stomach and intestines. This muscle works involuntarily. Lastly, cardiac muscle is found in the heart and allows it to beat. Nervous tissue senses internal and external cues, or stimuli, and processes and transmits information. This type of tissue is found in the spinal cord and throughout the body as neurons. Cellular membranes Both prokaryotic and eukaryotic cells have a plasma membrane. This type of membrane is a double layer of lipids that separates the cell’s interior from the outside environment. This double layer is called a phospholipid bilayer. A phospholipid is made of a hydrophilic (water-loving) phosphate head and two hydrophobic (water-fearing) fatty acid tails. The phospholipids arrange themselves, as shown below. Organelles Organelle Type of cell where it Function is found Cell wall Plant cell only Protect and support the cell Allow oxygen and water to pass through Cell membrane Plant and animal cells Controls what comes in and out of the cell Nucleus Plant and animal cells Controls the cell activities Houses DNA Cytoplasm Plant and animal cells Home to the cell’s organelles Mitochondria Plant and animal cells Breaks down sugar molecules to create energy Endoplasmic reticulum Plant and animal cells Carries protein and other materials from one part of the cell to another Ribosomes Plant and animal cells Produces proteins Golgi bodies Plant and animal cells Receives proteins and other materials from the endoplasmic reticulum and packages them to be redistributed Chloroplasts Plant cell only Captures energy from sunlight and uses it to produce food for cells Vacuoles Plant and animal cells Storage area for cells Lysosomes Plant cell: uncommon Animal cell: common Use chemicals to break down food particles into smaller ones Breaks down old cells Cell cycle DNA replication, mitosis, and cytokinesis are the main events of the diploid cell cycle. The cell cycle for somatic cells is different than the cell cycle for gametes. Somatic cells are diploid (contain two homologous chromosomes) and go through mitosis, whereas gametes are haploid (contains only a single set of unpaired chromosomes) and go through meiosis. During DNA replication of somatic cells, the two strands of the DNA double helix are separated. Each strand serves as a template for a new strand to be created. DNA replication takes place during interphase – the preparatory phase for mitosis. There are three stages of interphase: • Gap1: normal cellular function with increased protein synthesis. The cell nearly doubles in size. • Synthesis: the cell duplicates its DNA. Initiator proteins locate the origin of replication on the parent DNA strands. The double helix is “unzipped,” the enzyme primase adds an RNA primer, and the enzyme DNA polymerase elongates the chain. Elongation is terminated when a specific termination sequence is reached. • Gap 2: cell grows and prepares for division. After DNA replication has taken place, mitosis can begin. Mitosis describes how replicated chromosomes are separated into two new nuclei – how the mother cell is divided into two genetically identical daughter cells. There are six phases of mitosis, below: • Prophase: the chromosomes condense • Prometaphase: the nuclear envelope disintegrates and microtubules enter the nucleus • Metaphase: the microtubules attach to the center of each chromosome and start to pull each chromosome to opposite ends of the cell • Anaphase: The proteins that bind chromatids are cleaved and the two daughter chromosomes are fully pulled to opposite ends of the cell • Telophase: events that occurred during prophase and prometaphase are reversed – the chromosomes relax again and the nuclear envelope is reformed. Cytokinesis begins after mitosis. The cell is pinched into two newly formed daughter cells, each containing a complete set of chromosomes. Cytokinesis is the final stage of cell division. It is the division of cytoplasm to form two new cells. Cytokinesis begins as mitosis is ending. It takes place differently in animal and plant cells. Animal cell: Cell division occurs when a band called a contractile ring contracts inward and pinches the cell in two. The indentation produced by this pinching is called a cleavage furrow. Animal cells can be pinched in two because they are relatively soft. Plant cell: Plant cells are much more rigid than animal cells, due to their cell wall. It is for this reason that plant cells divide by building a cell plate down the middle of the cell. As the cell plate grows, it partitions the cell in two. DNA bases DNA (deoxyribonucleic acid) is a double helix made up of nucleotides. A nucleotide is made up of a sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), guanine (G), or cytosine (C). C and T are called pyrimidines, and have just one ring, whereas A and G have two rings and are called purines. DNA nucleotides assemble and link with covalent bonds. DNA nucleotides join in very specific ways. They always pair in this way: A and T, C and G. This is called complementary base pairing. Because of their shape and properties, they can only bond in this way. Enzymes Enzymes are a type of protein that can catalyze, or speed up, particular chemical reactions. While most enzymes are proteins, RNA molecules can act as enzymes too. Enzymes lower a reaction’s activation energy, which is the amount of energy needed for a reaction to begin. They work by binding with the reactant so that the reaction can occur with more ease and quicker. In order to catalyze a reaction, enzymes bind to one or more reactant molecules, called the substrate. The place where the substrates attach is called the active site. Exocytosis process Cells need to release molecules, such as waste and proteins, to the outside environment. Exocytosis is a form of transport in which materials are transported outside of the cell in membrane-bound vesicles. These vesicles fuse with the plasma membrane to release the materials. The vesicles could come from the Golgi apparatus and contain proteins. Other times they will contain waste. The vesicles go to the plasma membrane where they fuse with the membrane and release their contents. Passive transport Passive transport is the simplest form of transport across the membrane. Passive transport does not require the cell to use any energy. It involves a molecule diffusing (moving) down a concentration gradient across a membrane. A concentration gradient is a region of space over which the concentration of a molecule changes. Molecules naturally move from high concentration to low concentration. There are several kinds of passive transport, as shown below: The image above shows diffusion. This is when a molecule moves from areas of high concentration to low concentration until the concentration becomes equal throughout the total area. Other types of passive transport include selective permeability, channel proteins, and facilitated diffusion. Selective permeability means that some substances are let through the membrane while others are kept out. Facilitated diffusion involves either channel proteins or carrier proteins. Channel proteins make hydrophilic tunnels, allowing target molecules to pass through by diffusion. The image above shows carrier proteins. These proteins can change their shape to move a target molecule through the membrane. Tonicity Tonicity is the ability of an extracellular solution to make water move into or out of a cell by osmosis. The tonicity is related to the osmolarity, which is the total concentration of all solutes in the solution. Low osmolarity means that there are few particles of solute per liter of solution, whereas a solution with high osmolarity has more solute particles per liter of solution. The terms hypotonic, hypertonic and isotonic are used to compare osmolarity of a cell to the fluid around it. If the extracellular fluid has lower osmolarity than the fluid in the cell, it is hypotonic to the cell. The net flow of water will be into the cell. If the extracellular fluid has higher osmolarity than the fluid in the cell, it is hypertonic to the cell, which means water will move out of the cell to the area with higher solute concentration. In an isotonic solution, the concentrations of solute are the same inside and outside the cell, and there is no water movement. Homeostasis Homeostasis is the tendency to resist change in order to maintain a stable, relatively constant internal environment. It typically involves negative and positive feedback loops. The negative feedback loops counteract changes of various properties from their target values, which are called set points. The positive feedback loops intensify the initiating stimuli, which causes the system to move away from its starting state, causing a change instead of returning to homeostasis. Temperature, pH, glucose levels and other values are all maintained to keep the body at homeostasis. Negative feedback loop: Positive feedback loop: Metric conversions The metric system is based on multiples of 10, which allows for easy conversions. Below are two diagrams to show the units for length, weight and volume, as well as how to convert within those units. Mnemonic King Henry Died Base Unit Drinking Chocolate Milk Length: Abbreviation: Kilometer km Hectometer hm Decameter dam Meter m Decimeter dm Centimeter cm Millimeter mm Weight: Abbreviation: Kilogram kg Hectogram hg Decagram dag Gram g Decigram dg Centigram cg Milligram mg Volume: Abbreviation: Kiloliter kL Hectoliter hL Decaliter daL Liter L Deciliter dL Centiliter cL Milliliter mL How many are in 1 meter/gram/liter 0.001 0.01 0.1 1 10 100 1000 How many meters/grams/liters are in this unit? 1000 100 10 1 0.1 0.01 0.001 BIGGER SMALLER Genetics Genetics encompasses the study of inheritable traits. Most people know that half of a human’s DNA is inherited from his or her mother and the other half is inherited from his or her father through the uniting of gametes (ovum and sperm). Gametes are haploid cells – the nucleus of gametes only contains a single set of chromosomes. Humans are diploid organisms, which means all the somatic cells (body cells aside from gametes) in the human body are diploid cells (contains two homologous copies of each chromosome - one from the mother and one from the father). Genotype The unification of the gametes creates a new set of chromosomes which contains a new genetic code. This DNA sequence contains the genotype, which is partially responsible for the phenotype (characteristic) of an individual. Other factors which affect phenotype are epigenetic factors and environmental factors. In general, we denote characteristics as dominant or recessive. A capital letter denotes dominant and a lower case letter denotes recessive. For a homozygous trait, both letters must be the same case (FF or ff). A heterozygous trait is denoted by mixed case (Ff). Phenotype Punnett squares are used to determine possible genotypes of offspring. Based on the genotype, a phenotype will occur. Phenotypes are the physical representation of the genotype, which is the genetic code. Example: If two parents (both Ff) have freckles (which are dominant), their offspring may or may not have freckles. The resulting genotype options are FF, Ff, and ff. If the offspring has a genotype of FF or Ff, they will have a phenotype of freckles. If the genotype is ff, the phenotype is few or no freckles. *** Scientific method The scientific method is a logical problem-solving approach used by biologists and many other scientists. It has five basic steps, plus one feedback step: 1. Make an observation. 2. Ask a question. 3. Form a hypothesis, or testable explanation. 4. Make a prediction based on the hypothesis. 5. Test the prediction. 6. Use the results to make new hypotheses or predictions. Example: Step of the Method Example Observation The toaster doesn’t toast the bread. Ask a question “Why doesn’t the toaster toast?” Hypothesis If the electrical outlet is replaced, then the toaster will work. Make predictions If the toaster is plugged into a different outlet, then the toaster will work and prove the outlet is broken Test predictions Plug the toaster into a different outlet and try toasting again Hypothesis is supported OR Hypothesis is not supported Bread is toasted after trying the toaster in a new outlet. What is actually wrong with the other outlet? The bread still doesn’t toast. Maybe the toaster itself is broken. The scientific method is a cycle, rather than a simple chain process. A strong scientific hypothesis uses an if/then format. Personal prepositions should not be included. Use the following format to help: “If (action to be done in the experiment), then (prediction of what you expect the outcome to be).” Microscopy Microscopy involves the study of samples using a microscope. The microscope was mainstreamed in the mid 19th century and has since revolutionized biology. Microscopy includes three main branches – optical, electron, and scanning probe. Scanning probe microscopy is less utilized and involves the scanning of a probe over the surface of an object. Optical and electron microscopy are widely used and involve the diffraction, reflection, or refraction of beams interacting with the specimen being studied. Optical, also known as light microscopy, involves the passing of visible light through or reflected from a sample to magnify it. This method is straightforward and inexpensive, but has limitations such as magnification limits and the frequent necessity to stain samples prior to viewing. The compound microscope shown below is widely used. To operate a compound microscope: • Connect power source • Clean oculars with nonabrasive cloth • Lower stage completely • Secure slide to mount with clips • Select the lowest magnification objective lens • Look through oculars and use the coarse adjustment knob to bring the sample into clear view. • Select the next lowest magnification objective lens, and only adjust the fine focus. Refrain from adjusting the coarse focus. Bring the image into clear view. • If desired, repeat the previous step again. • If desired, rotate the objective lens such that the sample is in between the second highest and highest magnification (typically between the 40x and 100x). Add a drop of immersion oil to the coverslip and fully rotate the highest magnification objective lens into place. View the sample and adjust the fine focus if necessary. Immersion oil increases the numerical aperture of the view through its high refractive index. Cells and Tissues Practice Worksheet Use the word bank below to write the name of the organelle with its correct function. Word bank: Cell wall, cell membrane, nucleus, cytoplasm, mitochondria, endoplasmic reticulum, ribosome, Golgi bodies, chloroplasts, vacuoles, lysosome 1. Protects and supports the cell 2. Produces proteins _ 3. Controls what comes in and out of the cell _ 4. Receives proteins and other materials from the endoplasmic reticulum and packages them to be redistributed _ _ 5. Home to the cell’s organelles _ 6. Breaks down sugar molecules to create energy _ 7. Captures energy from sunlight and uses it to produce food for cells _ 8. Houses DNA _ _ _ 9. Carries protein and other materials from one part of the cell to another _ 10. Storage area for cells 11. Breaks down old cells 12. List two organelles from above that are found only in plants: and For the following statements, answer true or false: 13. Eukaryotic cells do not have a nucleus. _ 14. Eukaryotic cells are in bacteria. _ 15. Prokaryotic cells do not have a nucleus. _ 16. Epithelial cells are in the heart. _ 17. All muscle tissue is voluntarily controlled. _ 18. Cell membranes are a single layer. _ 19. Connective tissue includes tendons. _ 20. Nervous tissue is made of neurons. _ Genetics For the following statements, answer true or false: 1. DNA is found in all cells, even viruses. _ 2. DNA and RNA have the same bases. _ 3. DNA and RNA have the same purposes. _ 4. Purines have two carbon rings. _ 5. Pyrimidines have two carbon rings. _ 6. Purines bond to other purines. _ 7. Phenotype is not physically shown. _ 8. DNA forms a single helix. _ 9. DNA is made up of lipids. _ 10. DNA is made up of nucleotides. _ For the following strands of DNA code, write the matching nucleotide sequence. 11. CGTAAGCGCTAATTA 12. TCTTAAATGATCGATC 13. AATGAATAGCTAGCTT For each of the genotypes below, determine what phenotypes would be possible. Use the statement provided to decide the phenotypes. 14. Purple flowers are dominant to white flowers. PP Pp _ _ pp _ 15. Brown eyes are dominant to blue eyes bb _ BB Bb _ _ Metric Conversions 1. 712 g = _ kg 2. 222.7 L = _ dL 3. 16.45 m = _ cm 4. 39.56 g = _ mg 5. 10.5 g = _ kg 6. 3.54 mg = _ dg 7. 28.6 g = _ hg 8. 910 m = _ dm 9. 0. kg = _ cg 10. 1488 cm = _ hm 11. Ethan lives at one end of Park Avenue. Brian lives at the other end of the avenue. It is 5.8 kilometers from one end of Park Avenue to the other. If Ethan walks 2.79 kilometers towards Brian’s house, how many more METERS does he have to walk to get there? 12. Devin had chicken pox and had to stay inside even though he didn’t feel very bad at all. He decided to make a cake to surprise his mother. The recipe said he needed 4 deciliters of milk. How many LITERS of milk did he need? 13. Aaron and Noah wanted to have a contest to see which of their paper airplanes could fly the longest distance. Aaron’s plane flew 4 meters. Noah’s plane flew 79 centimeters. How much further did Aaron’s plane fly in METERS? Biological Processes Write the name of the process that applies to the statements below. Word bank: Anaerobic Respiration, Cytokinesis, Homeostasis, Passive Transport, Exocytosis 1. Most commonly performed by bacteria and archaea _ 2. The tendency to resist change in order to maintain a stable, relatively constant internal environment 3. Waste products are carbon dioxide and ethanol 4. Occurs when oxygen is not present _ 5. Uses a contractile ring to divide cells 6. Cells need to release molecules, such as waste and proteins, to the outside environment 7. Uses a cell plate to divide cells 8. A cleavage furrow occurs because of a contractile ring 9. Vesicles fuse with the plasma membrane to release the materials 10. A type of cellular respiration 11. Typically involves negative and positive feedback loops 12. Begins as mitosis is ending 13. Temperature, pH, glucose levels and other values are all maintained by this process. 14. The simplest form of transport across the membrane _ 15. Does not require the cell to use any energy to move substances 16. Uses the electrons from the fuel molecules to pass through the electron transport chain, which drives ATP synthesis 17. The final stage of cell division 18. Substances naturally move from high concentration to low concentration 19. Include selective permeability, channel proteins, channel proteins, and facilitated diffusion 20. Form of transport in which materials are transported outside of the cell in membrane-bound vesicles _ Enzymes and Tonicity 1. The substance with which an enzyme reacts is its _ _. 2. Is an enzyme “used up” by the reaction it catalyzes? Explain. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 3. In what way does an enzyme affect the reaction it catalyzes? How does the enzyme produce this effect? _ _ _ _ _ _ _ _ _ _ _ _ Match the description with the osmotic conditions mentioned below: A. Isotonic B. Hypertonic C. Hypotonic 4. solution with a lower solute concentration. 5. solution in which the solute concentration is the same. 6. condition plant cells require. 7. condition that animal cells require. 8. red blood cell bursts (cytolysis). 9. plant cell loses turgor pressure (plasmolysis). 10. solution with a higher solute concentration. 11. plant cell with good turgor pressure. 12. solution with high water concentration. Label the tonicity for each solution (isotonic, hypertonic, hypotonic). 13. _ _ 14. _ 15. 16. _ _ 17. _ 18. _ ANSWER KEY: Cells and Tissues 1. Protects and supports the cell Cell wall _ 2. Produces proteins _ Ribosomes_ 3. Controls what comes in and out of the cell Cell membrane 4. Receives proteins and other materials from the endoplasmic reticulum and packages them to be redistributed _Golgi bodies_ 5. Home to the cell’s organelles _Cytoplasm 6. Breaks down sugar molecules to create energy _ _Mitochondria 7. Captures energy from sunlight and uses it to produce food for cells Chloroplast 8. Houses DNA _ Nucleus_ 9. Carries protein and other materials from one part of the cell to another __Endoplasmic reticulum__ 10. Storage area for cells Vacuole_ 11. Breaks down old cells Lysosome 12. List two organelles from above that are found only in plants: Chloroplast__ and Cell wall 13. Eukaryotic cells do not have a nucleus. False 14. Eukaryotic cells are in bacteria. False 15. Prokaryotic cells do not have a nucleus. True 16. Epithelial cells are in the heart. False 17. All muscle tissue is voluntarily controlled. False 18. Cell membranes are a single layer. False 19. Connective tissue includes tendons. True 20. Nervous tissue is made of neurons. True ANSWER KEY: Genetics 1. DNA is found in all cells, even viruses. False 2. DNA and RNA have the same bases. False 3. DNA and RNA have the same purposes. False 4. Purines have two carbon rings. True 5. Pyrimidines have two carbon rings. False 6. Purines bond to other purines. False 7. Phenotype is not physically shown. False 8. DNA forms a single helix. False 9. DNA is made up of lipids. False 10. DNA is made up of nucleotides. True 11. CGTAAGCGCTAATTA GCATTCGCGATTAAT 12. TCTTAAATGATCGATC AGAATTTACTAGCTAG 13. AATGAATAGCTAGCTT TTACTTATCGATCGAA 14. Purple flowers are dominant to white flowers. PP Purple Pp __Purple__ pp __White 15. Brown eyes are dominant to blue eyes bb _ Blue _ BB Brown Bb _ Brown ANSWER KEY: Metric Conversions 1. 712 g = 0.712 kg 2. 222.7 L = 2227 dL 3. 16.45 m = 1645 cm 4. 39.56 g = 39560 mg 5. 10.5 g = 0.0105 kg 6. 3.54 mg = 0.0354 dg 7. 28.6 g = 0.286 hg 8. 910 m = 9100 dm 9. 0. kg = 670 cg 10. 1488 cm = 0.1488 hm 11. Ethan lives at one end of Park Avenue. Brian lives at the other end of the avenue. It is 5.8 kilometers from one end of Park Avenue to the other. If Ethan walks 2.79 kilometers towards Brian’s house, how many more METERS does he have to walk to get there? Solution: (5.8 – 2.79) km = 3.01 km = 3010 m 12. Devin had chicken pox and had to stay inside even though he didn’t feel very bad at all. He decided to make a cake to surprise his mother. The recipe said he needed 4 deciliters of milk. How many LITERS of milk did he need? Solution: 4 dL = 0.4 L 13. Aaron and Noah wanted to have a contest to see which of their paper airplanes could fly the longest distance. Aaron’s plane flew 4 meters. Noah’s plane flew 79 centimeters. How much further did Aaron’s plane fly in METERS? Solution: Aaron’s plane = 4 m, Noah’s plane = 79 cm = 0.79 m Aaron’s plane flew further by (4.0 – 0.79) m = 3.21 m ANSWER KEY: Biological Processes 1. Most commonly performed by bacteria and archaea Anaerobic respiration 2. The tendency to resist change in order to maintain a stable, relatively constant internal environment Homeostasis 3. Waste products are carbon dioxide and ethanol Anaerobic respiration 4. Occurs when oxygen is not present Anaerobic respiration 5. Uses a contractile ring to divide cells Cytokinesis__ 6. Cells need to release molecules, such as waste and proteins, to the outside environment Exocytosis 7. Uses a cell plate to divide cells Cytokinesis 8. A cleavage furrow occurs because of a contractile ring Cytokinesis 9. Vesicles fuse with the plasma membrane to release the materials Exocytosis 10. A type of cellular respiration Anaerobic respiration 11. Typically involves negative and positive feedback loops Homeostasis 12. Begins as mitosis is ending Cytokinesis 13. Temperature, pH, glucose levels and other values are all maintained by this process. Homeostasis 14. The simplest form of transport across the membrane _ Passive transport 15. Does not require the cell to use any energy to move substances Passive transport 16. Uses the electrons from the fuel molecules to pass through the electron transport chain, which drives ATP synthesis Anaerobic respiration 17. The final stage of cell division Cytokinesis 18. Substances naturally move from high concentration to low concentration Passive transport 19. Include selective permeability, channel proteins, channel proteins, and facilitated diffusion Passive transport 20. Form of transport in which materials are transported outside of the cell in membrane-bound vesicles Exocytosis _ ANSWER KEY: Enzymes and Tonicity 1. The substance with which an enzyme reacts is its _Substrate . 2. Is an enzyme “used up” by the reaction it catalyzes? Explain. No. The enzyme separates again from the newly formed product after the reaction is complete. 3. In what way does an enzyme affect the reaction it catalyzes? How does the enzyme produce this effect? Enzymes speed up reactions. This happens because of the lock and key arrangement of the active site of the enzyme and substrate. 4. C. Hypotonic solution with a lower solute concentration. 5. A. Isotonic solution in which the solute concentration is the same. 6. A. Isotonic condition plant cells require. 7. A. Isotonic condition that animal cells require. 8. C. Hypotonic red blood cell bursts (cytolysis). 9. B. Hypertonic plant cell loses turgor pressure (plasmolysis). 10. B. Hypertonic solution with a higher solute concentration. 11. C. Hypotonic plant cell with good turgor pressure. 12. C. Hypotonic solution with high water concentration. 13. Hypotonic 14. Isotonic 15. Hypertonic 16. Hypotonic 17. Isotonic 18. Hypertonic HESI Style Biology Practice Questions: 1. A patient receives an antibiotic for symptoms of the flu. Why doesn’t the medication work? a. The medication is for a different type of flu. b. The medication is not suitable for treating the flu. c. The medication is not a strong enough dosage amount to cure the patient. d. None of the above 2. The nucleus is important in a cell because: a. It stores the DNA b. It supports the cell c. It makes protein d. It makes energy out of food 3. Cellular respiration happens so that a. Cells can copy DNA b. Cells can breathe c. Cells can convert nutrients to energy d. Cells can divide 4. Anaerobic respiration happens in because __. a. Animals; they need energy b. Plants; they use sunlight c. Bacteria; they live in environments with low oxygen. 5. All bacteria are bad and always cause infections. a. True b. False 6. Which of the following is not true about antibiotics? a. They can interfere with the bacteria’s ability to survive b. They can affect how bacteria multiply c. They can cause more bacteria to grow d. They only work on bacteria 7. Prokaryotic cells: a. Have a nucleus b. Have a capsule c. Have membrane bound organelles d. Cannot move on their own 8. Select the cell parts that are present in plant cells but not animal cells (there may be more than one answer): a. Cell membrane b. Cell wall c. Ribosome d. Chloroplast 9. Epithelial tissue can be found in: a. Organ lining b. Heart muscle c. Tendons d. Spinal cord 10. What are the three types of muscle tissue? a. Cardiac, spinal, stomach b. Smooth, skeletal, cardiac c. Neuron, epithelial, collagen d. None of the above 11. Which type of tissue is fat? a. Connective b. Muscle c. Nervous d. Epithelial 12. What type of cells have a cell membrane? a. Prokaryotic only b. Eukaryotic only c. Both prokaryotic and eukaryotic d. None of the above 13. How is the plasma membrane arranged? a. In a single layer made of proteins b. In a double layer made of proteins c. In a single layer of phospholipids d. In a double layer of phospholipids 14. The head of a phospholipid: a. Is water loving b. Is water fearing c. Is on the outer side of the layer d. Both A and C 15. Cytokinesis happens so that: a. DNA can duplicate b. Organelles can convert energy c. Bacteria can be killed d. Daughter cells can divide 16. Animal cells use which of the following methods to divide? a. Contractile ring b. Cell plate c. Animals cells do not divide d. None of the above 17. Why can animal cells use a contractile ring but plant cells cannot? a. Plant cells can use both ways to divide b. Animal cells divide faster so it needs to pinch apart c. Plant cells are too rigid to use a contractile ring d. None of the above 18. DNA bases include all but which of the following? a. Adenine b. Thymine c. Uracil d. Cytosine 19. RNA bases include all but which of the following? a. Adenine b. Thymine c. Uracil d. Cytosine 20. Choose the two bases that are purines: a. A b. C c. T d. G 21. Choose the two bases that have two carbon rings: a. A b. C c. T d. G 22. C and T are known as: a. Purines b. Pyrimidines c. Both d. None of the above 23. Select the option that best shows complementary base pairing in DNA: a. A and G b. A and C c. A and A d. A and T 24. Select the strand of DNA that would match this segment: ACTTGCA a. TGAACGT b. GACCATG c. ACTTGCA d. None of the above 25. DNA is stored in: a. The nucleus b. Ribosomes c. Endoplasmic reticulum d. Mitochondria 26. Enzymes can _ reactions a. Catalyze b. Inhibit c. Stop d. None of the above 27. Enzymes are typically _ _. a. Fats b. Proteins c. Sugars d. Neurons 28. Which of the following is not true about enzymes? a. They catalyze reactions b. They raise the activation energy needed c. They have an active site d. They are typically proteins 29. Epithelial cells are: a. Polarized b. Neutral c. Larger than other cells d. None of the above 30. The apical side of an epithelial cell: a. Is exposed to fluid or air b. Is on the bottom side of the cell c. Does not allow any substances to pass through d. None of the above 31. Which of the following organisms would not have eukaryotic cells? a. Bacteria b. Dog c. Human d. Onion 32. Cells need to use exocytosis because: a. They need to get energy b. They need to protect against invaders c. They need to remove waste d. They need to divide 33. A child is sick. They have a body temperature that exceeds 37ºC. The body senses this and begins to sweat in order to lower the temperature. What is this an example of? a. Positive feedback loop b. Negative feedback loop c. Both loops d. None of the above 34. Homeostasis is necessary because a. It maintains temperature b. It maintains pH c. It maintains glucose levels d. All of the above 35. A pencil measures 8cm long. What is this in mm? a. 80 mm b. 800 mm c. .8 mm d. .08 mm 36. A scientist needs 12 mL of a solution. They have a bottle with .12L in it. Do they have enough? a. Yes, they have exactly what they need b. Yes, they have more than what they need c. No, they do not have enough d. None of the above 37. The purpose of the mitochondria is: a. Control the cell b. Create energy c. Create proteins d. Package waste for removal 38. Which organelle is responsible for making proteins? a. Ribosome b. Chloroplast c. Lysosome d. Mitochondria 39. Which of the following is false? a. Animal cells use lysosomes to break down old cells b. Animal cells use chloroplasts to gain energy c. Plant cells have a cell wall to maintain structure d. All of the above are true 40. Which of the following is always true of substances? a. They can travel through all membranes b. They move from low concentration to high concentration c. They move from high concentration to low concentration d. They cannot move 41. This type of passive transport uses proteins that change shape to move a target molecule through the membrane: a. Diffusion b. Carrier proteins c. Channel proteins d. None of the above 42. Phenotype refers to the _ of an individual. a. Genetic makeup b. Actual physical appearance c. Recessive alleles d. None of the above 43. When the genotype consists of a dominant and a recessive allele, the phenotype will be like the _ allele. a. Dominant b. Recessive c. Both d. Neither 44. The fur color in a population of dogs is controlled by two alleles: black (B) and tan (b). The black allele exhibits complete dominance. If the phenotype of the dog is tan fur, what is its genotype? a. BB b. Bb c. bb d. Not enough information 45. Using the information in #44, what would the phenotype be if the offspring is Bb? a. Black b. Black and tan c. Tan d. Not enough information 46. Listed below are the steps in the scientific method. Put them in the correct order: a. Ask a question. b. Test the prediction. c. Make an observation. d. Make a prediction based on the hypothesis. e. Form a hypothesis, or testable explanation. f. Use the results to make new hypotheses or predictions 47. Which of the following is the best example of a hypothesis? a. Dogs like treats b. Red is the best color c. If I eat 100 donuts, then I will feel sick d. If a plant is exposed to red light, then it will show less growth than natural light. 48. Tonicity refers to the movement of: a. Water b. Solute c. Cells d. None of the above 49. If a hard-boiled egg is placed in a beaker of salt water, then the egg will: a. Expand because water will move into the egg b. Shrivel because water will leave the egg c. Will remain the same d. None of the above 50. Using the example in #49, which type of solution is the egg placed into? a. Hypertonic b. Isotonic c. Hypotonic d. None of the above 51. Which of the following is true of the Krebs cycle? a. It is a redox reaction involving proteins produced during glycolysis b. It is a redox reaction involving sugars produced during glycolysis c. Protons are passed along a gradient to produce ATP d. It is also known as the glycolic acid cycle 52. Which of the following is true of Glycolysis? a. It requires the absence of Oxygen b. It occurs in the presence of Oxygen c. It is the final step of fermentation d. It is the final step of anaerobic respiration 53. The three main events of the haploid cell cycle are: a. DNA replication, mitosis, and cytokinesis b. DNA replication, meiosis, and cytokinesis c. DNA replication, cytokinesis, and degradation d. Mitosis, meiosis, and apoptosis 54. The difference between diploid and haploid is as follows: a. Diploid organisms are multicellular. Haploid organisms are single cellular b. Diploid cells are somatic. Haploid cells are gametes. c. Diploid cells have two sets of homologous chromosomes. Haploid cells have one set of unpaired chromosomes. d. More than one of the above is true. e. None of the above is true. 55. The phases of mitosis include: a. Prophase, interphase, metaphase, anaphase, and telophase b. Prophase, prophase, metaphase, anaphase, and cytokinesis c. Prophase, prometaphase, metaphase, anaphase, and telophase d. Prophase, interphase, prophase, anaphase, and telophase 56. During which phase of mitosis does the nuclear envelope disintegrate? a. Prophase b. Prophase c. Prometaphase d. Metaphase e. Anaphase 57. Which is true of gametes? a. They are diploid cells b. They are haploid cells c. They are somatic d. A & C are true e. B & C are true 58. Which of the following is true of heterozygous traits? a. They are haploid b. They are denoted AA c. They are denoted aa d. They are denoted Aa e. More than one of the above is true 59. Which of the following is true of homozygous traits? a. They are haploid b. They are denoted AA c. They are denoted aa d. They are denoted Aa e. More than one of the above is true 60. Which is true of the term Phenotype? a. It is the genetic code b. Phenotype determines genotype c. Genotype determines phenotype d. Genotype, epigenetic factors, and environmental factors determine phenotype 61. Optical Microscopy a. Utilizes scanning electrons b. Utilizes visible light c. Utilizes dye for samples d. More than one of the above is true. 62. The procedure to focus an image using a compound microscope involves a. Adjusting the coarse adjustment each time a new magnification is selected b. Adjusting the fine adjustment each time a new magnification is selected c. Adjusting the stage each time a new magnification is selected d. All of the above e. None of the above Answer Key: HESI Biology Practice Questions and Answers: 1. A patient receives an antibiotic for symptoms of the flu. Why doesn’t the medication work? a. The medication is for a different type of flu. b. The medication is not suitable for treating the flu. c. The medication is not a strong enough dosage amount to cure the patient. d. None of the above The correct answer is B. Antibiotics are used for treating bacterial infections, but the flu is caused by a virus. Although symptoms can be similar in case of a cold (bacteria) or the flu (virus), viruses cannot be treated using antibiotics. 2. The nucleus is important in a cell because: a. It stores the DNA b. It supports the cell c. It makes protein d. It makes energy out of food The correct answer is A. The nucleus is the “brain” of the cell and stores the DNA. A cell wall supports the cell (only if it is a plant). The ribosomes make protein and the mitochondria makes energy. 3. Cellular respiration happens so that a. Cells can copy DNA b. Cells can breathe c. Cells can convert nutrients to energy d. Cells can divide The correct answer is C. The term respiration typically triggers thoughts of breathing, but in this case, it is referring to the process cells undergo to convert nutrients into ATP. Copying DNA is transcription and translation. Cells themselves cannot breathe. Cell division is mitosis or meiosis, depending on the type of cell. 4. Anaerobic respiration happens in _ because _ . a. Animals; they need energy b. Plants; they use sunlight c. Bacteria; they live in environments with low oxygen. d. None of the above The correct answer is C. Animals and plants both use aerobic respiration because they have access to oxygen. Bacteria typically live in environments with little to no oxygen and must still produce energy to survive. 5. All bacteria are bad and always cause infections. a. True b. False The correct answer is B. Bacteria can be good, such as the bacteria in the intestines. This bacterium can become problematic if it travels to a location other than where it belongs. Pathogenic bacteria are bad and can cause infections, but not all bacteria are this type. 6. Which of the following is not true about antibiotics? a. They can interfere with the bacteria’s ability to survive b. They can affect how bacteria multiply c. They can cause more bacteria to grow d. They only work on bacteria The correct answer is C. Antibiotics only work on bacteria by either blocking its ability to grow or multiply, or completely killing the bacteria cells. 7. Prokaryotic cells: a. Have a nucleus b. Have a capsule c. Have membrane bound organelles d. Cannot move on their own The correct answer is B. Prokaryotic cells are simple, single celled organisms. They do not have a nucleus or membrane bound organelles. This type of cell can move on its own with a flagella or small hair-like fibers. 8. Select the cell parts that are present in plant cells but not animal cells (there may be more than one answer): a. Cell membrane b. Cell wall c. Ribosome d. Chloroplast The correct answer is B and D. Both plant and animal cells have a cell membrane and ribosomes, however only plant cells have a cell wall and chloroplasts. The cell wall is necessary for maintaining the shape and structure of the plant. Chloroplasts are necessary for photosynthesis. 9. Epithelial tissue can be found in: a. Organ lining b. Heart muscle c. Tendons d. Spinal cord The correct answer is A. Epithelial tissue is found in skin and all of the linings within the body. Heart muscle is muscle tissue, tendons are connective tissue and the spinal cord is nervous tissue. 10. What are the three types of muscle tissue? a. Cardiac, spinal, stomach b. Smooth, skeletal, cardiac c. Neuron, epithelial, collagen d. None of the above The correct answer is B. Smooth muscle is found in organs like the stomach, where it is involuntarily controlled. Skeletal muscle is found in voluntary muscles, like the bicep or quadriceps. Cardiac muscle is found only in the heart walls and works involuntarily to make the heart beat and pump blood. 11. Which type of tissue is fat? a. Connective b. Muscle c. Nervous d. Epithelial The correct answer is A. Fat is a type of loose connective tissue called adipose. Its job is to cushion organs. Fat is not made of muscle cells, neurons or epithelial cells. 12. What type of cells have a cell membrane? a. Prokaryotic only b. Eukaryotic only c. Both prokaryotic and eukaryotic d. None of the above The correct answer is C. Cell membranes are present in all types of cells. Its purpose is to hold in the fluids and other components of the cell and protect against external substances and invaders. 13. How is the plasma membrane arranged? a. In a single layer made of proteins b. In a double layer made of proteins c. In a single layer of phospholipids d. In a double layer of phospholipids The correct answer is D. The plasma membrane is made of a phospholipid bilayer that has two layers of phospholipids. The hydrophilic phosphate heads face the outside of the layers and the fatty acid tails face inward, since they are hydrophobic. 14. The head of a phospholipid: a. Is water loving b. Is water fearing c. Is on the outer side of the layer d. Both A and C The correct answer is D. The phosphate head is on the outer part of the bilayer because it is hydrophilic, which means that it can be in contact with water and not react. 15. Cytokinesis happens so that: a. DNA can duplicate b. Organelles can convert energy c. Bacteria can be killed d. Daughter cells can divide The correct answer is D. Cytokinesis happens at the end of mitosis. DNA has already duplicated during mitosis. Cytokinesis must happen so that they cell can divide into the daughter cells. 16. Animal cells use which of the following methods to divide? a. Contractile ring b. Cell plate c. Both d. None of the above The correct answer is A. Animal cells are soft and squishy, which allows them to be pinched apart by a contractile ring, unlike rigid plant cells that must build a cell plate to divide. 17. Why can animal cells use a contractile ring but plant cells cannot? a. Plant cells can use both ways to divide b. Animal cells divide faster so it needs to pinch apart c. Plant cells are too rigid to use a contractile ring The correct answer is C. Animal cells are soft and squishy, which allows them to be pinched apart by a contractile ring, unlike rigid plant cells that must build a cell plate to divide. 18. DNA bases include all but which of the following? a. Adenine b. Thymine c. Uracil d. Cytosine The correct answer is C. Uracil is a base found only in RNA. 19. RNA bases include all but which of the following? a. Adenine b. Thymine c. Uracil d. Cytosine The correct answer is B. RNA uses uracil in place of thymine. Uracil would pair with adenine. 20. Choose the two bases that are purines: a. A b. C c. T d. G The correct answer is A and D. Adenine and guanine are purines, which have two carbon rings. 21. Choose the two bases that have two carbon rings: a. A b. C c. T d. G The correct answer is A and D. Adenine and guanine have two carbon rings and are called purines. 22. C and T are known as: a. Purines b. Pyrimidines c. Both d. None of the above The correct answer is B. Cytosine and thymine are pyrimidines which have one carbon ring. 23. Select the option that best shows complementary base pairing in DNA: a. A and G b. A and C c. A and A d. A and T The correct answer is D. A purine (A) must pair with a pyrimidine (T). This eliminates options A and C. Adenine can only pair with thymine because of their shape and bonding ability. 24. Select the strand of DNA that would match this segment: ACTTGCA a. TGAACGT b. GACCATG c. ACTTGCA d. None of the above The correct answer is A. Purines must pair with pyrimidines in a specific way. A must pair with T; C must pair with G. So the complementary segment is TGAACGT. 25. DNA is stored in: a. The nucleus b. Ribosomes c. Endoplasmic reticulum d. Mitochondria The correct answer is A. Ribosomes produce proteins. The endoplasmic reticulum carries proteins to other parts of the cell. Mitochondria breaks down sugar to create energy. The nucleus stores the DNA and controls the cell. 26. Enzymes can _ reactions a. Catalyze b. Inhibit c. Stop d. None of the above The correct answer is A. Enzymes help to speed up reactions, not to inhibit or stop them. 27. Enzymes are typically _ _. a. Fats b. Proteins c. Sugars d. Neurons The correct answer is B. Enzymes are usually made of proteins, but a few can also be RNA. 28. Which of the following is not true about enzymes? a. They catalyze reactions b. They raise the activation energy needed c. They have an active site d. They are typically proteins The correct answer is B. Enzymes catalyze reactions, have an active site and are typically proteins. They also lower the activation energy needed for a reaction to occur, not raise it. 29. Epithelial cells are: a. Polarized b. Neutral c. Larger than other cells d. None of the above The correct answer is A. Epithelial cells have a top and bottom side, which shows that they are polarized. These sides (apical and basal) serve different purposes. 30. The apical side of an epithelial cell: a. Is exposed to fluid or air b. Is on the bottom side of the cell c. Does not allow any substances to pass through d. None of the above The correct answer is A. The apical side of an epithelial cell is the top side. This is the side that is either exposed to fluids or the air, or the inside of an organ. The bottom side of the cell is called the basal side. The apical side allows certain substances to pass through it. 31. Which of the following organisms would not have eukaryotic cells? a. Bacteria b. Dog c. Human d. Onion The correct answer is A. Dogs, humans and onions are all multi-cellular organisms which have eukaryotic cells. Bacteria are single-celled organisms that have prokaryotic cells. 32. Cells need to use exocytosis because: a. They need to get energy b. They need to protect against invaders c. They need to remove waste d. They need to divide The correct answer is C. Cells get energy through cellular respiration. Cells protect themselves with a cell membrane. Cells divide using cytokinesis. Exocytosis uses small vesicles to release either waste or substances for the body. 33. A child is sick. They have a body temperature that exceeds 37ºC. The body senses this and begins to sweat in order to lower the temperature. What is this an example of? a. Positive feedback loop b. Negative feedback loop c. Both d. None of the above The correct answer is B. A negative feedback loop works to return the body to homeostasis. In this example, the body identified a higher temperature, so it sent messages to the brain to signal for the body to sweat, which helps to cool the body and lower the temperature. 34. Homeostasis is necessary because a. It maintains temperature b. It maintains pH c. It maintains glucose levels d. All of the above The correct answer is D. Homeostasis is the tendency to resist change in order to maintain a stable, relatively constant internal environment. This includes maintaining temperature, pH levels and glucose levels. 35. A pencil measures 8cm long. What is this in mm? a. 80 mm b. 800 mm c. .8 mm d. .08 mm The correct answer is A. When changing from centimeters to millimeters, the decimal point moves one place value to the right. It takes 10 millimeters to make 1 centimeter, so it would take 80 millimeters to make 8 centimeters. 36. A scientist needs 12 mL of a solution. They have a bottle with 0.12L in it. Do they have enough? a. Yes, they have exactly what they need b. Yes, they have more than what they need c. No, they do not have enough d. None of the above The correct answer is B. 1 liter has 1000 milliliters in it. In order to convert from milliliters to liters, the decimal point would move three places to the left. So, the bottle has 120 mL of solution, a lot more than required 12 mL. 37. The purpose of the mitochondria is: a. Control the cell b. Create energy c. Create proteins d. Package waste for removal The correct answer is B. The nucleus controls the cell. The mitochondria create energy. The ribosomes create proteins and lysosomes package waste. 38. Which organelle is responsible for making proteins? a. Ribosome b. Chloroplast c. Lysosome d. Mitochondria The correct answer is A. The ribosomes create proteins. Chloroplasts convert sunlight to energy. Lysosomes package waste. The mitochondria create energy. 39. Which of the following is false? a. Animal cells use lysosomes to break down old cells b. Animal cells use chloroplasts to gain energy c. Plant cells have a cell wall to maintain structure d. All of the above are true The correct answer is B. Animal cells do not have chloroplasts since they cannot synthesize energy from sunlight. Only plants can do this. 40. Which of the following is always true about molecules? a. They can travel through all cell membranes b. They move from low concentration to high concentration without using energy c. They move from high concentration to low concentration without using energy d. They cannot move The correct answer is C. Molecules cannot travel through all types of membranes and they can move. Particles move from high to a low concentration to reach equilibrium. Molecules cannot move from a low to high concentration without outside energy like Active Transport. 41. This type of passive transport uses proteins that change shape to move a target molecule through the membrane: a. Diffusion b. Carrier proteins c. Channel proteins d. None of the above The correct answer is B. Diffusion allows substances to move through the membrane in order to reach equilibrium. Channel proteins allow substances to flow through the membrane. Carrier proteins must change shape to allow only specific target molecules through the membrane. 42. Phenotype refers to the _ of an individual. a. Genetic makeup b. Actual physical appearance c. Recessive alleles d. None of the above The correct answer is B. Genotype is the term for the actual genetic makeup of the individual, whereas phenotype is the physical expression of the genetics. 43. When the genotype consists of a dominant and a recessive allele, the phenotype will be like the _ allele. a. Dominant b. Recessive c. Both d. Neither The correct answer is A. The dominant allele will be expressed in the phenotype in most basic cases. If there is codominance, both traits may be expressed. 44. The fur color in a population of dogs is controlled by two alleles: black (B) and tan (b). The black allele exhibits complete dominance. If the phenotype of the dog is tan fur, what is its genotype? a. BB b. Bb c. bb d. Not enough information The correct answer is C. Tan fur is the recessive trait, which means that both alleles must be recessive i.e. bb. 45. Using the information in #44, what would the phenotype be if the offspring is Bb? a. Black b. Black and tan c. Tan d. Not enough information The correct answer is A. The black allele exhibits complete dominance, so even though the dog has one allele for black and one for tan, the black with show in the phenotype. 46. Listed below are the steps in the scientific method. Put them in the correct order: a. Ask a question. b. Test the prediction. c. Make an observation. d. Make a prediction based on the hypothesis. e. Form a hypothesis, or testable explanation. f. Use the results to make new hypotheses or predictions The correct answer is A, C, E, D, B, F. The scientific method in correct order is: Make an observation. Ask a question. Form a hypothesis, or testable explanation. Make a prediction based on the hypothesis. Test the prediction. Use the results to make new hypotheses or predictions. 47. Which of the following is the best example of a hypothesis? a. Dogs like treats b. Red is the best color c. If I eat 100 donuts, then I will feel sick d. If a plant is exposed to red light, then it will show less growth than natural light. The correct answer is D. Option A and B are biased statements and could be opinion based. Option C uses personal pronouns, which is not scientific. Option D shows an action, followed by a prediction that is testable without using personal pronouns. 48. Tonicity refers to the movement of: a. Water b. Solute c. Cells d. None of the above The correct answer is A. Water moves across the membrane to attempt to reach equilibrium. The cells and solute do not move. 49. If a hard-boiled egg is placed in a beaker of salt water, then the egg will: a. Expand because water will move into the egg b. Shrivel because water will leave the egg c. Will remain the same d. None of the above The correct answer is B. The beaker of salt water has a higher concentration of solute, so that water from the hard-boiled egg will move to the salt water in an attempt to reach equilibrium. This will cause the egg to shrivel or shrink. 50. Using the example in #49, which type of solution is the egg placed into? a. Hypertonic b. Isotonic c. Hypotonic d. None of the above The correct answer is A. Hypertonic refers to a solution with too much solute (higher solute concentration), so the water moves out into the solution. 51. Which of the follow