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Flashcards in week 9 Deck (76):
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1) The basic structural and functional unit of the human body is A) protein. B) the cell. C) tissue. D) the organ. E) the organ system.

1) The basic structural and functional unit of the human body is A) protein. B) the cell. * C) tissue. D) the organ. E) the organ system.

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2) Which of the following terms is not used to define the structure that separates the contents of a human cell from its surrounding medium? A) cell wall B) cell membrane C) plasma membrane D) plasmalemma E) both A and D

2) Which of the following terms is not used to define the structure that separates the contents of a human cell from its surrounding medium? A) cell wall * B) cell membrane C) plasma membrane D) plasmalemma E) both A and D

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3) The cell membrane includes A) integral proteins. B) glycolipids. C) phospholipids. D) all of the above E) A and C only

3) The cell membrane includes A) integral proteins. B) glycolipids. C) phospholipids. D) all of the above * E) A and C only

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4) Extracellular fluid serves as A) a storage area. B) a reserve area. C) a component of the phospholipid bilayer. D) a transport medium. E) a transport medium with large storage capacity.

4) Extracellular fluid serves as A) a storage area. B) a reserve area. C) a component of the phospholipid bilayer. D) a transport medium. * E) a transport medium with large storage capacity.

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5) The terminal web is best described as A) filaments of actin forming a layer just inside the cell membrane at the exposed cell surface. B) filaments of cytoskeleton forming a layer just inside the cell membrane at the exposed cell surface. C) filaments of actin forming a layer just inside the cell membrane at the unexposed cell surface. D) filaments of cytoskeleton forming a layer just inside the cell membrane at the unexposed cell surface. E) cytosol that has hardened.

5) The terminal web is best described as A) filaments of actin forming a layer just inside the cell membrane at the exposed cell surface. * B) filaments of cytoskeleton forming a layer just inside the cell membrane at the exposed cell surface. C) filaments of actin forming a layer just inside the cell membrane at the unexposed cell surface. D) filaments of cytoskeleton forming a layer just inside the cell membrane at the unexposed cell surface. E) cytosol that has hardened.

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6) In the mitochondrion, folds are to cristae as the contained fluid is to A) actin. B) microvilli. C) cytosol. D) basal body. E) matrix.

6) In the mitochondrion, folds are to cristae as the contained fluid is to A) actin. B) microvilli. C) cytosol. D) basal body. E) matrix. *

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7) Vesicles containing enzymes that neutralize toxins such as alcohol are A) lysosomes. B) peroxisomes. C) centrosomes. D) endosomes. E) toxisomes.

7) Vesicles containing enzymes that neutralize toxins such as alcohol are A) lysosomes. B) peroxisomes. * C) centrosomes. D) endosomes. E) toxisomes.

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8) When activated, lysosomes function in A) formation of new cell membranes. B) synthesis of proteins. C) digestion of foreign material. D) synthesis of lipids. E) cell division.

8) When activated, lysosomes function in A) formation of new cell membranes. B) synthesis of proteins. C) digestion of foreign material. * D) synthesis of lipids. E) cell division.

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9) The control center for cellular operations is the A) nucleus. B) mitochondria. C) Golgi apparatus. D) endoplasmic reticulum. E) ribosome.

9) The control center for cellular operations is the A) nucleus. * B) mitochondria. C) Golgi apparatus. D) endoplasmic reticulum. E) ribosome.

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10) The complex structures of DNA and protein found in the cell nucleus are A) nucleoplasm. B) chromosomes. C) histones. D) nucleases. E) mitochondria.

10) The complex structures of DNA and protein found in the cell nucleus are A) nucleoplasm. B) chromosomes. * C) histones. D) nucleases. E) mitochondria.

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11) The process of forming mRNA is called A) replication. B) transcription. C) translation. D) ribolation. E) auscultation.

11) The process of forming mRNA is called A) replication. B) transcription. * C) translation. D) ribolation. E) auscultation.

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12) The process of protein formation is called A) replication. B) transcription. C) translation. D) mitosis. E) auscultation.

12) The process of protein formation is called A) replication. B) transcription. C) translation. * D) mitosis. E) auscultation.

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13) The movement of oxygen from an area of high concentration to an area of low concentration is an example of A) osmosis. B) active transport. C) diffusion. D) facilitated transport. E) filtration.

13) The movement of oxygen from an area of high concentration to an area of low concentration is an example of A) osmosis. B) active transport. C) diffusion. * D) facilitated transport. E) filtration.

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14) Water molecules and small ions enter a cell through A) channels in some integral proteins. B) peripheral proteins. C) lipid channels. D) peripheral carbohydrates. E) small holes in the lipid layer of the membrane.

14) Water molecules and small ions enter a cell through A) channels in some integral proteins. * B) peripheral proteins. C) lipid channels. D) peripheral carbohydrates. E) small holes in the lipid layer of the membrane.

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15) A solution that contains a lower solute concentration than the cytoplasm of a cell is called A) merotonic. B) hypertonic. C) isotonic. D) hypotonic. E) homotonic.

15) A solution that contains a lower solute concentration than the cytoplasm of a cell is called A) merotonic. B) hypertonic. C) isotonic. D) hypotonic. * E) homotonic.

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16) Crenation occurs when a blood cell is placed in a(n) _____ solution. A) isotonic B) hypertonic C) hypotonic D) merotonic E) homotonic

16) Crenation occurs when a blood cell is placed in a(n) _____ solution. A) isotonic B) hypertonic * C) hypotonic D) merotonic E) homotonic

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17) The process by which molecules such as glucose are moved into cells along their concentration gradient with the help of membrane-bound carrier proteins is called A) osmosis. B) facilitated diffusion. C) active transport. D) endocytosis. E) exocytosis.

17) The process by which molecules such as glucose are moved into cells along their concentration gradient with the help of membrane-bound carrier proteins is called A) osmosis. B) facilitated diffusion. * C) active transport. D) endocytosis. E) exocytosis.

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18) Diffusion of a substance across the cell membrane is influenced by all of the following, except A) its ability to dissolve in water. B) the size of the membrane channel. C) the charge on the ion or molecule. D) the charge of the membrane. E) its solubility in the lipid membrane.

18) Diffusion of a substance across the cell membrane is influenced by all of the following, except A) its ability to dissolve in water. * B) the size of the membrane channel. C) the charge on the ion or molecule. D) the charge of the membrane. E) its solubility in the lipid membrane.

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19) Facilitated diffusion differs from ordinary diffusion in that A) facilitated diffusion expends no ATP. B) facilitated diffusion moves molecules from an area of their higher concentration to their lower concentration. C) the rate of molecular movement is limited by the number of available carrier molecules. D) facilitated diffusion never eliminates the concentration gradient. E) the rate of molecular movement is not limited by the number of available carrier molecules

19) Facilitated diffusion differs from ordinary diffusion in that A) facilitated diffusion expends no ATP. B) facilitated diffusion moves molecules from an area of their higher concentration to their lower concentration. C) the rate of molecular movement is limited by the number of available carrier molecules. * D) facilitated diffusion never eliminates the concentration gradient. E) the rate of molecular movement is not limited by the number of available carrier molecules

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20) A process that requires cellular energy to move a substance against its concentration gradient is called A) active transport. B) passive transport. C) facilitated transport. D) osmosis. E) diffusion.

20) A process that requires cellular energy to move a substance against its concentration gradient is called A) active transport. * B) passive transport. C) facilitated transport. D) osmosis. E) diffusion.

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21) The packaging of extracellular materials in a vesicle at the cell surface for importation into the cell is called A) osmosis. B) active transport. C) facilitated transport. D) endocytosis. E) an ion exchange pump.

21) The packaging of extracellular materials in a vesicle at the cell surface for importation into the cell is called A) osmosis. B) active transport. C) facilitated transport. D) endocytosis. * E) an ion exchange pump.

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22) The principal cations in our body fluids are _____ and _____. A) sodium; potassium B) calcium; magnesium C) sodium; magnesium D) chloride; potassium E) sodium; chloride

22) The principal cations in our body fluids are _____ and _____. A) sodium; potassium * B) calcium; magnesium C) sodium; magnesium D) chloride; potassium E) sodium; chloride

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23) In order to maintain cellular homeostasis, an important exchange pump within the cell membrane ejects _____ ions from the cell and imports _____ ions. A) potassium; calcium B) sodium; calcium C) potassium; sodium D) sodium; potassium E) calcium; sodium

23) In order to maintain cellular homeostasis, an important exchange pump within the cell membrane ejects _____ ions from the cell and imports _____ ions. A) potassium; calcium B) sodium; calcium C) potassium; sodium D) sodium; potassium * E) calcium; sodium

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24) When describing a cell’s membrane potential, the cell interior is A) more positively charged than the exterior. B) more negatively charged than the exterior. C) electrically neutral. D) continuously reversing its electrical charge. E) positively charged whenever the sodium–potassium pump is active.

24) When describing a cell’s membrane potential, the cell interior is A) more positively charged than the exterior. B) more negatively charged than the exterior. * C) electrically neutral. D) continuously reversing its electrical charge. E) positively charged whenever the sodium–potassium pump is active.

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25) Endocytosis is A) a method for transporting substances across the cell membrane. B) a method for metabolizing within the cytosol. C) a form of anabolism. D) a manner in which lysosomes are formed. E) a method for synthesizing products.

25) Endocytosis is A) a method for transporting substances across the cell membrane. * B) a method for metabolizing within the cytosol. C) a form of anabolism. D) a manner in which lysosomes are formed. E) a method for synthesizing products.

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26) Peroxisomes A) contain enzymes that break down hydrogen peroxide. B) absorb and break down fatty acids, generating hydrogen peroxide in the process. C) are the same organelle as lysosomes. D) A and B E) none of the above

26) Peroxisomes A) contain enzymes that break down hydrogen peroxide. B) absorb and break down fatty acids, generating hydrogen peroxide in the process. C) are the same organelle as lysosomes. D) A and B * E) none of the above

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27) A mature red blood cell lacks a nucleus. Thus, it A) can repair itself rather readily. B) is malformed. C) is normal, but its function will be impaired. D) will be a long-lived cell. E) cannot repair itself and will disintegrate within a few months.

27) A mature red blood cell lacks a nucleus. Thus, it A) can repair itself rather readily. B) is malformed. C) is normal, but its function will be impaired. D) will be a long-lived cell. E) cannot repair itself and will disintegrate within a few months. *

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28) Chromosomes consist of _____ and _____. A) RNA; carbohydrates B) DNA; lipids C) DNA; proteins D) water; RNA E) RNA; proteins

28) Chromosomes consist of _____ and _____. A) RNA; carbohydrates B) DNA; lipids C) DNA; proteins * D) water; RNA E) RNA; proteins

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29) In the course of a semester, items began disappearing from the A&P lab. Students claimed that they saw nobody remove any items from the classroom. The instructor decided to investigate this phenomenon. Which of the following could have been used to identify the culprit using DNA fingerprinting? A) skin scrapings. B) hair samples. C) photo identification. D) indirect observation. E) A and B

29) In the course of a semester, items began disappearing from the A&P lab. Students claimed that they saw nobody remove any items from the classroom. The instructor decided to investigate this phenomenon. Which of the following could have been used to identify the culprit using DNA fingerprinting? A) skin scrapings. B) hair samples. C) photo identification. D) indirect observation. E) A and B *

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30) The functional units of DNA are A) chromosomes. B) genes. C) proteins. D) codons. E) RNA.

30) The functional units of DNA are A) chromosomes. B) genes. * C) proteins. D) codons. E) RNA.

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31) Specific proteins are manufactured through the interaction of _____ and _____. A) multiple enzymes; three types of RNA B) multiple enzymes; two types of RNA C) multiple carbohydrates; three types of DNA D) multiple proteins; three types of DNA E) multiple enzymes; three types of DNA

31) Specific proteins are manufactured through the interaction of _____ and _____. A) multiple enzymes; three types of RNA * B) multiple enzymes; two types of RNA C) multiple carbohydrates; three types of DNA D) multiple proteins; three types of DNA E) multiple enzymes; three types of DNA

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32) The type of transport process that always requires energy or an active process is termed A) diffusion. B) carrier-mediated transport. C) vesicular transport. D) freely permeable. E) impermeable.

32) The type of transport process that always requires energy or an active process is termed A) diffusion. B) carrier-mediated transport. C) vesicular transport. * D) freely permeable. E) impermeable.

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33) Cell shrinkage is to _____ as cell bursting is to _____. A) crenation; lysis B) lysis; crenation C) hypotonic; isotonic D) isotonic; hypotonic E) isotonic; hypertonic

33) Cell shrinkage is to _____ as cell bursting is to _____. A) crenation; lysis * B) lysis; crenation C) hypotonic; isotonic D) isotonic; hypotonic E) isotonic; hypertonic

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34) Two types of vesicular transport include A) endocytosis and indocytosis. B) endocytosis and exocytosis. C) exocytosis and indocytosis. D) pinocytosis and active transport. E) diffusion and active transport.

34) Two types of vesicular transport include A) endocytosis and indocytosis. B) endocytosis and exocytosis. * C) exocytosis and indocytosis. D) pinocytosis and active transport. E) diffusion and active transport.

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35) A unit in messenger RNA consisting of a set of three consecutive nucleotides is termed a/n A) amino acid. B) tRNA. C) rRNA. D) codon. E) pore.

35) A unit in messenger RNA consisting of a set of three consecutive nucleotides is termed a/n A) amino acid. B) tRNA. C) rRNA. D) codon. * E) pore.

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36) A carbohydrate that cannot cross cell membranes that is commonly administered to patients suffering blood loss is A) saline solution. B) salt solution. C) glucose. D) isotonic saline. E) dextran.

36) A carbohydrate that cannot cross cell membranes that is commonly administered to patients suffering blood loss is A) saline solution. B) salt solution. C) glucose. D) isotonic saline. E) dextran. *

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37) What is the first part of the cell that is affected when the pH of extracellular fluid changes? A) nucleolus B) cilia C) the cytosol D) cell membrane E) cytoskeleton

37) What is the first part of the cell that is affected when the pH of extracellular fluid changes? A) nucleolus B) cilia C) the cytosol D) cell membrane * E) cytoskeleton

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38) Which endoplasmic reticulum modifies and packages newly synthesized proteins? A) the ribosomal reticulum B) the proteosomes reticulum C) the raised reticulum D) the smooth reticulum E) the rough reticulum

38) Which endoplasmic reticulum modifies and packages newly synthesized proteins? A) the ribosomal reticulum B) the proteosomes reticulum C) the raised reticulum D) the smooth reticulum E) the rough reticulum *

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39) Inside the cell, membrane proteins are bound to the A) cytoplasm. B) cytoskeleton. C) protein fibers. D) phospholipid bilayer. E) cell membrane.

39) Inside the cell, membrane proteins are bound to the A) cytoplasm. B) cytoskeleton. * C) protein fibers. D) phospholipid bilayer. E) cell membrane.

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40) The endoplasmic reticulum is responsible for A) drug and toxin neutralization. B) protein, carbohydrate, and lipid synthesis. C) storage of synthesized molecules. D) all of the above E) both A and C

40) The endoplasmic reticulum is responsible for A) drug and toxin neutralization. B) protein, carbohydrate, and lipid synthesis. C) storage of synthesized molecules. D) all of the above * E) both A and C

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41) A substance containing atoms of different elements that are bonded together is called a(n) A) molecule. B) compound. C) mixture. D) isotope. E) solution.

41) A substance containing atoms of different elements that are bonded together is called a(n) A) molecule. B) compound. * C) mixture. D) isotope. E) solution.

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42) Special catalytic molecules called _____ control chemical reactions in the human body. A) enzymes B) cytozymes C) cofactors D) activators E) cytochormes

42) Special catalytic molecules called _____ control chemical reactions in the human body. A) enzymes * B) cytozymes C) cofactors D) activators E) cytochormes

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43) All organic compounds in the human body contain all of the following, except A) hydrogen. B) oxygen. C) carbon. D) calcium. E) both A and D

43) All organic compounds in the human body contain all of the following, except A) hydrogen. B) oxygen. C) carbon. D) calcium. * E) both A and D

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44) Which of the following is not a function of protein? A) support B) transport C) metabolic regulation D) storage of genetic information E) movement

44) Which of the following is not a function of protein? A) support B) transport C) metabolic regulation D) storage of genetic information * E) movement

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45) Haemolysis may occur when a blood cell is placed into A) isotonic solution. B) hypertonic solution. C) hypotonic solution. D) merotonic solution. E) homotonic.

45) Haemolysis may occur when a blood cell is placed into A) isotonic solution. B) hypertonic solution. C) hypotonic solution. * D) merotonic solution. E) homotonic.

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46) If a cell lacked the enzyme DNA polymerase, it could not A) form protein. B) form complementary sequences of DNA. C) link pieces of DNA together. D) form spindle fibers. E) form a new nuclear membrane during telophase.

46) If a cell lacked the enzyme DNA polymerase, it could not A) form protein. B) form complementary sequences of DNA. * C) link pieces of DNA together. D) form spindle fibers. E) form a new nuclear membrane during telophase.

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47) Compared to the extracellular fluid, cytosol contains A) a higher concentration of sodium ion. B) a relatively high concentration of dissolved proteins. C) relatively low supplies of carbohydrates. D) relatively few amino acids. E) no lipids.

47) Compared to the extracellular fluid, cytosol contains A) a higher concentration of sodium ion. B) a relatively high concentration of dissolved proteins. * C) relatively low supplies of carbohydrates. D) relatively few amino acids. E) no lipids.

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48) If an animal cell lacked centrioles, it would not be able to A) move. B) synthesize proteins. C) produce DNA. D) metabolize sugars. E) divide.

48) If an animal cell lacked centrioles, it would not be able to A) move. B) synthesize proteins. C) produce DNA. D) metabolize sugars. E) divide. *

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49) Each of the following statements concerning mitochondria is true, except one. Identify the exception. A) The mitochondrial cristae increase the inner surface area of the organelle. B) The matrix of the mitochondria contains metabolic enzymes involved in energy production. C) Respiratory enzymes are attached to the surface of the cristae. D) The mitochondria contain no DNA or RNA. E) The mitochondria produce most of a cell’s ATP.

49) Each of the following statements concerning mitochondria is true, except one. Identify the exception. A) The mitochondrial cristae increase the inner surface area of the organelle. B) The matrix of the mitochondria contains metabolic enzymes involved in energy production. C) Respiratory enzymes are attached to the surface of the cristae. D) The mitochondria contain no DNA or RNA. * E) The mitochondria produce most of a cell’s ATP.

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50) Each of the following is a function of smooth endoplasmic reticulum, except A) removal and storage of calcium ions. B) modification of protein products. C) synthesis of steroid hormones. D) synthesis of triglycerides in liver cells. E) detoxification of drugs in liver cells.

50) Each of the following is a function of smooth endoplasmic reticulum, except A) removal and storage of calcium ions. B) modification of protein products. * C) synthesis of steroid hormones. D) synthesis of triglycerides in liver cells. E) detoxification of drugs in liver cells.

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51) Two solutions are separated by a semipermeable membrane with the same properties as a cell membrane. Solution A is 5 percent glucose and solution B is 10 percent glucose. Under these circumstances, which of the following would most likely occur? A) Water will move from solution A to solution B. B) Water will move from solution B to solution A. C) Glucose will move from solution A to solution B. D) Glucose will move from solution B to solution A. E) At equilibrium the concentration of glucose will be higher in solution B.

51) Two solutions are separated by a semipermeable membrane with the same properties as a cell membrane. Solution A is 5 percent glucose and solution B is 10 percent glucose. Under these circumstances, which of the following would most likely occur? A) Water will move from solution A to solution B. * B) Water will move from solution B to solution A. C) Glucose will move from solution A to solution B. D) Glucose will move from solution B to solution A. E) At equilibrium the concentration of glucose will be higher in solution B.

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52) If the amount of sodium ion in blood plasma increases, which of the following would initially occur? A) The blood osmotic pressure will increase. B) The blood osmotic pressure will decrease. C) The blood osmotic pressure will stay the same. D) The blood hydrostatic pressure will increase. E) The blood hydrostatic pressure will decrease.

52) If the amount of sodium ion in blood plasma increases, which of the following would initially occur? A) The blood osmotic pressure will increase. * B) The blood osmotic pressure will decrease. C) The blood osmotic pressure will stay the same. D) The blood hydrostatic pressure will increase. E) The blood hydrostatic pressure will decrease.

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53) If the concentration of sodium ions in the fluid surrounding cells decreases and the concentration of other solutes remains constant, A) the cells will shrink. B) the cells will swell. C) the fluid outside of the cells will become isotonic. D) the fluid outside of the cells will become hypertonic. E) the cells will not change.

53) If the concentration of sodium ions in the fluid surrounding cells decreases and the concentration of other solutes remains constant, A) the cells will shrink. B) the cells will swell. * C) the fluid outside of the cells will become isotonic. D) the fluid outside of the cells will become hypertonic. E) the cells will not change.

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54) The movement of a particular amino acid across the cell membrane (along its concentration gradient) is impaired when a molecule chemically similar to the amino acid is added to the extracellular fluid. The movement of the amino acid through the membrane is by A) osmosis. B) diffusion. C) facilitated diffusion. D) active transport. E) pinocytosis.

54) The movement of a particular amino acid across the cell membrane (along its concentration gradient) is impaired when a molecule chemically similar to the amino acid is added to the extracellular fluid. The movement of the amino acid through the membrane is by A) osmosis. B) diffusion. C) facilitated diffusion. * D) active transport. E) pinocytosis.

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55) Generally, cells with slower mitotic rates A) are stem cells. B) do not exhibit cytokinesis. C) have longer life spans. D) are reproductive cells. E) lack the enzyme DNA polymerase.

55) Generally, cells with slower mitotic rates A) are stem cells. B) do not exhibit cytokinesis. C) have longer life spans. * D) are reproductive cells. E) lack the enzyme DNA polymerase.

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56) ________________________form the bilayer that separates cell from environment

56) ________________________form the bilayer that separates cell from environment Answer: phospholipids

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57) Some ___________________________act as gates, allowing ions to cross the plasma membrane

57) Some ___________________________act as gates, allowing ions to cross the plasma membrane Answer: integral proteins

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58) All cell contents between plasma membrane and nucleus is known as __________________

58) All cell contents between plasma membrane and nucleus is known as __________________ Answer: cytoplasm

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59) The transport mechanism allowing ingestion of solid particles by white blood cells is called ____________________

59) The transport mechanism allowing ingestion of solid particles by white blood cells is called ______________________ Answer: phagocytosis

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60) The fluid portion of the cytoplasm is the ___________

60) The fluid portion of the cytoplasm is the _________________________. Answer: cytosol

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61) The _________________________ is the boundary between the cell and its environment.

61) The _________________________ is the boundary between the cell and its environment. Answer: plasma membrane

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62) The __________________ have polar carbohydrate heads and nonpolar hydrocarbon tails; they are found only in the outer layer of the plasma membrane.

62) The __________________ have polar carbohydrate heads and nonpolar hydrocarbon tails; they are found only in the outer layer of the plasma membrane. Answer: glycolipids

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63) Membrane ________________ have diverse functions including serving as ion channels and cell-identity markers.

63) Membrane ________________ have diverse functions including serving as ion channels and cell-identity markers. Answer: proteins

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64) The property of membranes that allows some substances to pass more readily than others is called _________________________

64) The property of membranes that allows some substances to pass more readily than others is called ______________________________. Answer: selective permeability

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65) The normal intracellular concentration of glucose is approximately 5%. An infusion containing 10% glucose would be __________________ to the cell.

65) The normal intracellular concentration of glucose is approximately 5%. An infusion containing 10% glucose would be __________________ to the cell. Answer: hypertonic

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66) The ____________________ is the network of microtubules, intermediate filaments and microfilaments that help support and shape the cell and help organize its contents.

66) The ____________________ is the network of microtubules, intermediate filaments and microfilaments that help support and shape the cell and help organize its contents. Answer: cytoskeleton

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67) _______________ are small sacs that transport materials from the endoplasmic reticulum to the Golgi complex or from the Golgi complex to other parts of the cell.

67) _______________ are small sacs that transport materials from the endoplasmic reticulum to the Golgi complex or from the Golgi complex to other parts of the cell. Answer: Vesicles

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68) _________________ is the self-destruction of the cell due to release of lysosomal enzymes.

68) _________________ is the self-destruction of the cell due to release of lysosomal enzymes. Answer: Autolysis

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69) _________________________ regulate the passage of materials in and out of the nucleus.

69) _________________________ regulate the passage of materials in and out of the nucleus. Answer: Nuclear pores

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70) ____ are the heredity units that provide instructions for making proteins.

70) ____ are the heredity units that provide instructions for making proteins. Answer: Genes

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71) _____ is the enzyme that catalyzes transcription of DNA.

71) _____ is the enzyme that catalyzes transcription of DNA. Answer: RNA polymerase

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72) _____ is the division of nuclear contents in somatic cells.

72) _____ is the division of nuclear contents in somatic cells. Answer: Mitosis

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73) ____ is the programmed death of cells that are no longer needed.

73) ____ is the programmed death of cells that are no longer needed. Answer: Apoptosis

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74) Discuss the fluid mosaic model of plasma membrane structure. (5 marks)

Answer: Proteins "float" among phospholipids; phospholipid bilayer, with hydrophobic ends facing each other and hydrophilic ends facing either ECF or ICF; phospholipids can move sideways within layer; glycolipids (cellular identity markers) face ECF; cholesterol molecules (for stability) among phospholipids of both layers of the bilayer; integral proteins (channels, transporters, etc.) extend across phospholipid bilayer; peripheral proteins (enzymes, cytoskeleton anchors, etc.) loosely attached to either the inner or outer surface of the membrane.

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75) Name and describe the four phases of mitosis in sequence.

Answer: 1. Prophase: chromatin fibers shorten and coil into chromosomes; nucleoli and nuclear envelope disappear; centrosomes with centrioles move to opposite poles of cell; mitotic spindle appears 2. Metaphase: centromeres of chromatid pairs line up on metaphase plate of cell 3. Anaphase: centromeres divide; identical sets of chromosomes move to opposite poles of cell 4. Telophase: nuclear envelope reappears to enclose chromosomes; chromosomes revert to chromatin; nucleoli reappear; mitotic spindle disappears.

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76) What is the ‘cell theory’?

2) Activity of the organism depends on individual and collective activity of cells; 3) Biochemical activities of cells are dictated by subcellular structure; 4) Continuity of life has a cellular basis