Microscopy Quiz PDF

### Microscopy Quiz Section 1: Parts of a Microscope 1. **What part of the microscope do you look through to see the sample?** - A) Objective lens - B) Eyepiece (ocular lens) - C) Stage - D) Coarse focus knob 2. **Which part moves the stage up and down to bring the sample into focus?** -...

### Microscopy Quiz Section 1: Parts of a Microscope 1. **What part of the microscope do you look through to see the sample?** - A) Objective lens - B) Eyepiece (ocular lens) - C) Stage - D) Coarse focus knob 2. **Which part moves the stage up and down to bring the sample into focus?** - A) Diaphragm - B) Fine focus knob - C) Coarse focus knob - D) Objective lens 3. **What does the diaphragm do on a microscope?** - A) Magnifies the sample - B) Controls the light intensity - C) Moves the stage up and down - D) Focuses the image #### Section 2: Microscopy Terminology 4. **What does magnification refer to in microscopy?** - A) The sharpness of the image - B) The enlargement of the image - C) The contrast of the image - D) The color of the image 5. **What is the function of resolution in microscopy?** - A) Increases the size of the image - B) Improves the sharpness and detail of the image - C) Adjusts the brightness - D) Changes the color of the sample 6. **How does staining a sample improve microscopy?** - A) Increases contrast - B) Enhances magnification - C) Increases resolution - D) Reduces glare 7. **What is the total magnification if you use a 10x eyepiece with a 40x objective?** - A) 400x - B) 50x - C) 40x  - D) 100x #### Section 3: Objective Lenses and Bacterial Smears 8. **Which objective lens is commonly used to view bacterial smears?** - A) 4x - B) 10x - C) 40x - D) 100x 9. **What total magnification is generally needed to observe bacterial cells clearly?** - A) 40x - B) 100x - C) 400x - D) 1000x 10. **For larger samples, such as tissues or eukaryotic cells, which objectives are typically used?** - A) 4x or 10x - B) 40x or 100x - C) 10x or 40x - D) 100x or 400x #### Section 4: Types of Microscopy 11. **Which type of microscopy is most commonly used in a lab for observing stained specimens?** - A) Bright-field microscopy - B) Dark-field microscopy - C) Phase contrast microscopy - D) Electron microscopy 12. **Which type of microscopy is ideal for observing live, unstained specimens?** - A) Bright-field microscopy - B) Dark-field microscopy - C) Electron microscopy - D) Fluorescence microscopy 13. **What type of microscopy is required for observing viruses due to their very small size?** - A) Bright-field - B) Dark-field - C) Phase contrast - D) Electron microscopy #### Section 5: Specimen Preparation 14. **What is a wet mount used for in microscopy?**  - A) Observing dead cells - B) Observing live cells in liquid - C) Staining bacterial cells - D) Heat-fixing bacterial cells 15. **What is a bacterial smear typically used for?** - A) Observing live cells - B) Preparing and staining bacteria for viewing - C) Observing large tissue sections - D) Measuring cell size 16. **Why is heat-fixing done when preparing a bacterial smear?** - A) To increase magnification - B) To attach cells to the slide and kill bacteria - C) To improve contrast - D) To observe live cells 17. **What can be seen in a wet mount that is usually not visible in a smear?** - A) Bacterial shapes - B) Fixed and stained cells - C) Cell movement - D) Viral structures #### Section 6: Terminology and Smear Preparation 18. **What term describes round bacterial cells?** - A) Bacillus - B) Coccus - C) Spirillum - D) Rod 19. **What happens if a smear is too thick?** - A) You see the sample more clearly - B) It increases contrast - C) It makes it hard to see individual cells - D) It improves resolution 20. **What objective is typically used to view bacterial smears, and at what magnification?** - A) 10x, 100x total - B) 40x, 400x total - C) 100x, 1000x total - D) 4x, 40x total --- ### Answers 1. B 2. C 3. B 4. B 5. B 6. A 7. A 8. D 9. D 10. C 11. A 12. B 13. D 14. B 15. B 16. B 17. C 18. B 19. C 20. C ### Chapter 3: Microscopy 1. **How is total magnification calculated on a microscope?** - A) By adding the objective and eyepiece magnifications - B) By dividing the objective magnification by the eyepiece magnification - C) By multiplying the objective magnification by the eyepiece magnification - D) By subtracting the eyepiece magnification from the objective magnification 2. **If you’re using a 10x eyepiece and a 40x objective, what is the total magnification?** - A) 400x - B) 40x - C) 50x - D) 100x 3. **Why is resolving power important in microscopy?** - A) It allows the microscope to zoom in - B) It increases the contrast of the image - C) It determines the microscope’s ability to distinguish two close points as separate - D) It adjusts the total magnification 4. **Which of the following improves resolution?** - A) Using longer wavelengths of light - B) Using oil immersion with a high-power objective - C) Decreasing the magnification - D) Increasing the contrast 5. **What is the importance of contrast in microscopy?** - A) It helps to focus the image - B) It enhances the color of the specimen - C) It makes the specimen stand out against the background - D) It reduces light refraction --- ### Chapter 2: The Chemistry of Biology 6. **What is the smallest unit of matter?** - A) Molecule - B) Atom - C) Proton - D) Electron 7. **What type of bond involves the sharing of electrons?** - A) Ionic bond - B) Covalent bond - C) Hydrogen bond - D) Polar bond 8. **What type of reaction involves the removal of water to form a bond?** - A) Hydrolysis - B) Combustion - C) Dehydration synthesis - D) Oxidation 9. **What are the four main macromolecules in biology?** - A) Carbohydrates, proteins, lipids, and nucleic acids - B) Water, ions, carbohydrates, and proteins - C) Proteins, enzymes, DNA, and RNA - D) Lipids, sugars, salts, and nucleotides 10. **Which property of water allows it to dissolve many substances?** - A) Cohesion - B) Polarity - C) High heat capacity  - D) Low density as a solid 11. **Which of the following terms describes a mixture where particles are evenly distributed but do not settle out?** - A) Solution - B) Suspension - C) Colloid - D) Emulsion 12. **Which is the monomer of proteins?** - A) Nucleotide - B) Monosaccharide - C) Amino acid - D) Fatty acid 13. **What type of bond links amino acids together in proteins?** - A) Hydrogen bond - B) Ionic bond - C) Glycosidic bond - D) Peptide bond 14. **Which macromolecule stores genetic information?** - A) Carbohydrate - B) Protein - C) Lipid - D) Nucleic acid 15. **What are the primary functions of lipids?** - A) Energy storage, insulation, and forming cell membranes - B) Catalyzing biochemical reactions - C) Transporting genetic information - D) Providing structural support to cells 16. **Which of the following differentiates DNA from RNA?** - A) DNA contains uracil instead of thymine - B) DNA is single-stranded, RNA is double-stranded - C) DNA has deoxyribose sugar, RNA has ribose sugar - D) DNA is involved in protein synthesis, RNA stores genetic information 17. **Why are proteins important biological molecules?** - A) They store genetic information - B) They act as catalysts, provide structure, and aid in cell functions - C) They store energy for long-term use - D) They are the main components of cell membranes 18. **How does a protein's shape relate to its function?** - A) Its shape doesn’t affect its function - B) The shape is important for its ability to store energy - C) The shape determines its interactions and specific functions in the body - D) Its shape is only important for storage functions --- ### Answers 1. C 2. A 3. C 4. B 5. C 6. B 7. B 8. C 9. A 10. B 11. C 12. C 13. D 14. D 15. A 16. C 17. B 18. C ### Chapter 5: Eukaryotic Life - Multiple-Choice Quiz 1. **Which of the following structures is only found in eukaryotic cells?** - A) Ribosomes - B) Nucleus - C) Cell membrane - D) Cytoplasm 2. **What is the primary function of the mitochondria in eukaryotic cells?** - A) Protein synthesis - B) Energy production - C) DNA storage - D) Lipid synthesis 3. **Which eukaryotic structure contains digestive enzymes and breaks down waste?** - A) Mitochondria - B) Lysosomes - C) Rough ER - D) Golgi apparatus 4. **Which type of cell wall is typically found in fungi?** - A) Peptidoglycan - B) Cellulose - C) Chitin - D) Silica 5. **What is endosymbiosis?** - A) The process of protein synthesis in the endoplasmic reticulum - B) A theory that certain organelles originated as symbiotic bacteria - C) A method of asexual reproduction in fungi - D) The division of eukaryotic cells by mitosis 6. **According to endosymbiosis theory, which organelles are thought to have originated from bacteria?** - A) Nucleus and Golgi apparatus - B) Endoplasmic reticulum and lysosomes - C) Mitochondria and chloroplasts - D) Ribosomes and vacuoles 7. **In which eukaryotic structure does protein synthesis primarily occur?** - A) Golgi apparatus - B) Smooth ER - C) Rough ER - D) Mitochondria 8. **What is the main function of the Golgi apparatus?** - A) Modifying and packaging proteins - B) Energy production - C) Protein synthesis - D) Lipid synthesis 9. **What is the role of fungi in nature?** - A) Producers in the ecosystem - B) Photosynthesis - C) Decomposition and nutrient recycling - D) Only as disease-causing pathogens 10. **Which fungal reproductive structure is used in asexual reproduction?** - A) Basidium - B) Sporangium - C) Mycelium - D) Chitin 11. **Which fungal group is commonly known as the "sac fungi"?** - A) Basidiomycetes - B) Zygomycetes - C) Ascomycetes - D) Deuteromycetes 12. **What is the unique structural component of algae cell walls?** - A) Cellulose - B) Chitin - C) Peptidoglycan - D) Silica 13. **Can algae be pathogenic?** - A) No, they are always harmless - B) Yes, some produce toxins harmful to humans - C) Only when they are ingested as food - D) Only in freshwater environments 14. **Which characteristic is shared by all protozoans?** - A) Photosynthetic ability - B) Multicellularity - C) Eukaryotic structure and motility - D) Rigid cell walls 15. **How are protozoans classified?** - A) Based on their nutritional requirements - B) Based on their shape and size - C) Based on their movement (e.g., flagella, cilia, pseudopodia) - D) Based on their ability to reproduce sexually --- ### Answers 1. **B** - Nucleus 2. **B** - Energy production 3. **B** - Lysosomes 4. **C** - Chitin 5. **B** - A theory that certain organelles originated as symbiotic bacteria 6. **C** - Mitochondria and chloroplasts 7. **C** - Rough ER 8. **A** - Modifying and packaging proteins 9. **C** - Decomposition and nutrient recycling 10. **B** - Sporangium 11. **C** - Ascomycetes 12. **D** - Silica 13. **B** - Yes, some produce toxins harmful to humans 14. **C** - Eukaryotic structure and motility 15. **C** - Based on their movement (e.g., flagella, cilia, pseudopodia) --- --- ### Chapter 5: Eukaryotic Life - Additional Multiple-Choice Quiz 16. **What is the main purpose of mitosis in eukaryotic cells?** - A) To produce genetic diversity - B) To produce identical cells for growth and repair - C) To reduce the chromosome number by half - D) To facilitate sexual reproduction 17. **What is the end result of meiosis?** - A) Two identical daughter cells - B) Four genetically unique cells with half the original chromosome number - C) A single cell with double the chromosome number - D) Four identical cells 18. **What is the correct order of organelles involved in protein synthesis?** - A) Nucleus, Golgi apparatus, rough ER, ribosomes - B) Ribosomes, rough ER, Golgi apparatus, vesicles - C) Mitochondria, ribosomes, smooth ER, Golgi apparatus - D) Rough ER, smooth ER, Golgi apparatus, lysosomes 19. **Which theory explains the origin of mitochondria and chloroplasts in eukaryotic cells?** - A) Endosymbiosis - B) Autogenesis - C) Abiogenesis - D) Chemiosmosis 20. **Which fungal phylum includes organisms that form mushrooms?**  - A) Zygomycota - B) Ascomycota - C) Basidiomycota - D) Deuteromycota 21. **Which of the following structures is involved in sexual reproduction in fungi?** - A) Sporangia - B) Mycelium - C) Basidia - D) Hyphae 22. **What term is used to describe algae that can produce harmful toxins?** - A) Bioluminescent algae - B) Red tide algae - C) Pathogenic algae - D) Chemotactic algae 23. **Protozoa are classified based on which of the following criteria?** - A) Their color - B) Their mode of movement - C) Their nutritional habits - D) Their cell wall composition 24. **What is a characteristic feature of protozoan cysts?** - A) They are the active, motile form of protozoa - B) They are a dormant form used for survival in harsh conditions - C) They are produced only during sexual reproduction - D) They contain toxins that harm their hosts 25. **Which structure in eukaryotic cells is responsible for lipid synthesis?** - A) Rough ER - B) Smooth ER - C) Golgi apparatus - D) Lysosome 26. **In which phase of mitosis do chromosomes line up at the cell’s equator?** - A) Prophase - B) Metaphase - C) Anaphase - D) Telophase 27. **Which structure is common to both prokaryotes and eukaryotes but has a different function in each?** - A) Cell membrane  - B) Nucleus - C) Mitochondria - D) Ribosomes 28. **What type of bond links nucleotides in nucleic acids?** - A) Peptide bond - B) Glycosidic bond - C) Phosphodiester bond - D) Ionic bond 29. **Which of the following is a role of fungi in the environment?** - A) Primary producers - B) Symbiotic nitrogen fixation - C) Decomposers - D) Parasites only 30. **What type of cells are protozoa, fungi, algae, and helminths classified as?** - A) Eukaryotic - B) Prokaryotic - C) Archaic - D) Unicellular only --- ### Answers 16. **B** - To produce identical cells for growth and repair 17. **B** - Four genetically unique cells with half the original chromosome number 18. **B** - Ribosomes, rough ER, Golgi apparatus, vesicles 19. **A** - Endosymbiosis 20. **C** - Basidiomycota 21. **C** - Basidia 22. **B** - Red tide algae 23. **B** - Their mode of movement 24. **B** - They are a dormant form used for survival in harsh conditions 25. **B** - Smooth ER 26. **B** - Metaphase 27. **A** - Cell membrane 28. **C** - Phosphodiester bond 29. **C** - Decomposers 30. **A** - Eukaryotic --- ### Multiple-Choice Quiz 1. **What is the term for the active, feeding stage in the life cycle of many protozoans?** - A) Cyst - B) Sporocyte - C) Trophozoite - D) Schizont 2. **What is the role of a biological vector in the life cycle of Plasmodium falciparum (malaria)?** - A) It provides a nutrient source for the parasite. - B) It transfers the parasite from one host to another. - C) It serves as the definitive host. - D) It destroys the parasite in the human body. 3. **In the life cycle of a parasite, what is the host in which sexual reproduction occurs called?** - A) Intermediate host - B) Primary host - C) Definitive host - D) Vector host 4. **Which of the following organisms is an intermediate host for Plasmodium falciparum?** - A) Humans - B) Mosquitoes - C) Fleas - D) Ticks 5. **Helminths, commonly known as worms, are classified into which of the following groups?** - A) Nematodes, Cestodes, and Trematodes - B) Arthropods, Sporozoans, and Protozoans - C) Fungi, Algae, and Protozoans - D) Bacteria, Viruses, and Fungi 6. **Which of the following characteristics applies to nematodes?** - A) They are segmented worms. - B) They have a long, flat, ribbon-like body. - C) They are cylindrical and non-segmented. - D) They are also known as flatworms. 7. **Pinworms are an example of which type of helminth?** - A) Nematode - B) Trematode - C) Cestode - D) Arthropod 8. **What is a biological vector?**  - A) An organism that provides nutrients to parasites - B) A carrier organism that transmits a pathogen through its body - C) An environment that supports parasite growth - D) An organism that does not interact with the pathogen 9. **Which type of arthropod transmits Lyme disease?** - A) Flea - B) Tick - C) Mosquito - D) Fly 10. **Which term describes the infestation of lice on a human host?** - A) Pediculosis - B) Cystitis - C) Infarction - D) Myiasis 11. **True or False: Eukaryotes and prokaryotes evolved independently.** - A) True - B) False 12. **Which organelle evolved from primitive cells trapped in larger cells?** - A) Nucleus - B) Mitochondria - C) Lysosome - D) Golgi apparatus 13. **Which type of organism is studied by microbiologists and is classified as a eukaryote?** - A) Bacteria - B) Algae - C) Viruses - D) Archaea 14. **Which of the following structures helps eukaryotic cells move and is different in structure than in prokaryotes?** - A) Cilia - B) Nucleus - C) Ribosome - D) Golgi apparatus 15. **What is the function of the glycocalyx in eukaryotic cells?** - A) Movement, replication, and protein production - B) Protection, adherence, and signal reception - C) Energy production, storage, and secretion  - D) Nutrient absorption, digestion, and detoxification 16. **True or False: Eukaryotic chromosomes are visible throughout the entire cell cycle.** - A) True - B) False 17. **Which organelle is responsible for packaging and transport of proteins in eukaryotic cells?** - A) Smooth ER - B) Rough ER - C) Golgi apparatus - D) Lysosomes 18. **What are vesicles that contain digestive enzymes called?** - A) Mitochondria - B) Ribosomes - C) Vacuoles - D) Lysosomes 19. **True or False: Mitochondria and chloroplasts contain 70S ribosomes and circular DNA.** - A) True - B) False 20. **What is a saprobe?** - A) A bacterium that infects only humans - B) A type of virus that targets plants - C) A fungus that derives nutrients from decaying material - D) A photosynthetic protozoan 21. **Which term is used to describe protozoan and helminth pathogens?** - A) Saprophytes - B) Trophozoites - C) Parasites - D) Vectors 22. **In helminths, which organ system is typically the most developed?** - A) Nervous system - B) Muscular system - C) Digestive system - D) Reproductive system 23. **True or False: Some helminths produce millions of eggs to overcome a high mortality rate of their ova.** - A) True  - B) False 24. **Which type of spores are contained in a sac-like head?** - A) Conidiospores - B) Sporangiospores - C) Ascospores - D) Basidiospores 25. **True or False: Algae do not cause any type of human disease.** - A) True - B) False --- ### Answers 1. **C** - Trophozoite 2. **B** - It transfers the parasite from one host to another 3. **C** - Definitive host 4. **A** - Humans 5. **A** - Nematodes, Cestodes, and Trematodes 6. **C** - They are cylindrical and non-segmented 7. **A** - Nematode 8. **B** - A carrier organism that transmits a pathogen through its body 9. **B** - Tick 10. **A** - Pediculosis 11. **A** - True 12. **B** - Mitochondria 13. **B** - Algae 14. **A** - Cilia 15. **B** - Protection, adherence, and signal reception 16. **B** - False 17. **C** - Golgi apparatus 18. **D** - Lysosomes 19. **A** - True 20. **C** - A fungus that derives nutrients from decaying material 21. **C** - Parasites 22. **D** - Reproductive system 23. **A** - True 24. **B** - Sporangiospores 25. **B** - False --- Here’s a continuation of the quiz with more multiple-choice questions based on the additional topics you provided. --- ### Multiple-Choice Quiz (Continued) 26. **What structure is used for locomotion in protozoa that move using whip-like motions?** - A) Cilia - B) Pseudopodia - C) Flagella - D) Fimbriae 27. **Which of the following protozoans is transmitted by the Anopheles mosquito and causes malaria?** - A) Giardia lamblia - B) Trypanosoma brucei - C) Plasmodium falciparum - D) Toxoplasma gondii 28. **Which stage in a protozoan life cycle is typically dormant and resistant to harsh environmental conditions?** - A) Trophozoite - B) Schizont - C) Cyst - D) Gametocyte 29. **Which is a key characteristic of eukaryotic flagella that differentiates them from prokaryotic flagella?** - A) They are used for sensory reception. - B) They have a "9+2" arrangement of microtubules. - C) They are shorter and more numerous. - D) They lack a basal body. 30. **Which of the following processes do fungi use for reproduction?** - A) Budding - B) Binary fission - C) Spore formation - D) Both A and C 31. **Which group of fungi is known for producing spores in a sac-like structure called an ascus?** - A) Basidiomycetes - B) Ascomycetes  - C) Zygomycetes - D) Deuteromycetes 32. **The theory of endosymbiosis explains the origin of which organelles?** - A) Nucleus and ribosomes - B) Golgi apparatus and lysosomes - C) Mitochondria and chloroplasts - D) Smooth and rough ER 33. **In protein synthesis, which is the correct order of organelles that a protein passes through?** - A) Nucleus → Rough ER → Golgi apparatus → Vesicle - B) Rough ER → Nucleus → Golgi apparatus → Vesicle - C) Smooth ER → Golgi apparatus → Rough ER → Vesicle - D) Golgi apparatus → Nucleus → Rough ER → Vesicle 34. **In endosymbiosis, the mitochondria are thought to have originated from what type of organism?** - A) Archaea - B) Cyanobacteria - C) Proteobacteria - D) Algae 35. **In eukaryotes, the structure responsible for packaging and modifying proteins is the:** - A) Smooth ER - B) Nucleus - C) Lysosome - D) Golgi apparatus 36. **Which of the following describes mitosis?** - A) Division of cytoplasm - B) Formation of gametes - C) Production of genetically identical cells - D) Formation of a zygote 37. **Which of the following best describes meiosis?** - A) Process that produces identical daughter cells - B) Type of cell division producing cells with half the original chromosome number - C) Division of a single cell into four identical cells - D) Process of dividing the cytoplasm of the cell 38. **Which characteristic is unique to algae among protists?** - A) Ability to photosynthesize - B) Possession of cilia for movement  - C) Absence of a nucleus - D) Ability to form cysts 39. **What is an example of a disease caused by a protozoan?** - A) Tuberculosis - B) Malaria - C) Measles - D) Ringworm 40. **What is the function of a definitive host in a parasitic life cycle?** - A) Site where the parasite reproduces sexually - B) Site where the parasite reproduces asexually - C) Host that only harbors larval forms of the parasite - D) Vector that transmits the parasite 41. **Which type of arthropod is a common vector for the spread of protozoan diseases?** - A) Flea - B) Fly - C) Mosquito - D) Tick 42. **True or False: Protozoa are eukaryotic microorganisms that always require a host to complete their life cycle.** - A) True - B) False 43. **Which of the following organelles is involved in detoxifying harmful substances in eukaryotic cells?** - A) Rough ER - B) Lysosome - C) Peroxisome - D) Golgi apparatus 44. **Which term describes the inflexible outer covering in some eukaryotic cells that provides structural support?** - A) Cell membrane - B) Capsule - C) Glycocalyx - D) Cell wall 45. **True or False: Algae can sometimes produce toxins that can affect humans, even though they do not directly cause infectious diseases.** - A) True - B) False --- ### Answers (Continued) 26. **C** - Flagella 27. **C** - Plasmodium falciparum 28. **C** - Cyst 29. **B** - They have a "9+2" arrangement of microtubules 30. **D** - Both A and C 31. **B** - Ascomycetes 32. **C** - Mitochondria and chloroplasts 33. **A** - Nucleus → Rough ER → Golgi apparatus → Vesicle 34. **C** - Proteobacteria 35. **D** - Golgi apparatus 36. **C** - Production of genetically identical cells 37. **B** - Type of cell division producing cells with half the original chromosome number 38. **A** - Ability to photosynthesize 39. **B** - Malaria 40. **A** - Site where the parasite reproduces sexually 41. **C** - Mosquito 42. **B** - False 43. **C** - Peroxisome 44. **D** - Cell wall 45. **A** - True --- Here’s a multiple-choice quiz based on the key concepts in microbial genetics from Chapter 6. --- ### Chapter 6: Microbial Genetics Multiple-Choice Quiz 1. **Which of the following best describes a genotype?** - A) The physical traits of an organism - B) The total genetic makeup of an organism - C) The specific location of a gene on a chromosome - D) A variation of a gene 2. **Which scientist is known for discovering the double-helix structure of DNA?** - A) Louis Pasteur - B) Rosalind Franklin - C) Alexander Fleming  - D) Robert Koch 3. **What base pairs with adenine in DNA?** - A) Thymine - B) Guanine - C) Cytosine - D) Uracil 4. **Which enzyme is primarily responsible for unwinding the DNA helix during replication?** - A) DNA ligase - B) DNA helicase - C) DNA polymerase - D) RNA polymerase 5. **During DNA replication, what is the main role of DNA polymerase?** - A) Unwinding the DNA helix - B) Joining Okazaki fragments - C) Synthesizing a new strand by adding nucleotides - D) Sealing gaps in the DNA backbone 6. **In prokaryotes, DNA replication occurs:** - A) In the nucleus - B) In the cytoplasm - C) In the mitochondria - D) In the ribosome 7. **How does RNA differ from DNA?** - A) RNA is double-stranded, while DNA is single-stranded. - B) RNA contains thymine instead of uracil. - C) RNA contains uracil instead of thymine. - D) RNA has a deoxyribose sugar, while DNA has a ribose sugar. 8. **What is the function of mRNA in gene expression?** - A) It synthesizes proteins. - B) It carries the genetic code from DNA to the ribosome. - C) It forms part of the ribosome. - D) It transfers amino acids to the ribosome. 9. **What type of RNA is involved in delivering amino acids to the ribosome during translation?** - A) mRNA - B) rRNA - C) tRNA - D) snRNA 10. **What is the function of a codon?** - A) It codes for an amino acid. - B) It serves as a signal for the start or stop of translation. - C) It is involved in DNA replication. - D) Both A and B 11. **In the process of translation, the start codon typically codes for which amino acid?** - A) Leucine - B) Methionine - C) Glycine - D) Phenylalanine 12. **In the Genetic Code table, a "nonsense codon" signifies:** - A) The start of translation - B) The end of translation - C) A mutation in the DNA - D) A repeat region in the DNA 13. **Which of the following is TRUE about the Lac operon?** - A) It is always active regardless of lactose presence. - B) It is repressible and activated only in the absence of lactose. - C) It is inducible and activated in the presence of lactose. - D) It is activated when glucose is abundant. 14. **In gene regulation, a gene that is always active is called:** - A) Repressible - B) Inducible - C) Constitutive - D) Regulatory 15. **Which term refers to a change in the DNA sequence that affects the genetic information?** - A) Mutation - B) Operon - C) Translation - D) Codon 16. **Which type of mutation results in a premature stop codon?** - A) Silent mutation - B) Missense mutation - C) Frameshift mutation - D) Nonsense mutation 17. **What process is used to repair thymine dimers caused by UV radiation?** - A) DNA replication  - B) Nucleotide excision repair - C) Reverse transcription - D) Frameshift repair 18. **The Ames test is used to:** - A) Study bacterial growth - B) Test for mutagenic properties of chemicals - C) Observe microbial conjugation - D) Detect auxotrophic mutants 19. **Which of the following describes horizontal gene transfer?** - A) Transfer of genes from parent to offspring - B) Transfer of genes between cells of the same generation - C) Transfer of genes during DNA replication - D) Transfer of genes through mitosis 20. **What is required for conjugation in bacteria?** - A) Physical contact between donor and recipient - B) A virus to mediate the transfer - C) DNA uptake from the environment - D) DNA synthesis in the cytoplasm 21. **Which of the following is NOT a method of horizontal gene transfer?** - A) Transduction - B) Transformation - C) Transcription - D) Conjugation 22. **In transduction, DNA is transferred between bacteria via:** - A) Pili - B) A viral vector - C) Direct cell contact - D) Endocytosis 23. **What does a repressor protein do in an operon model?** - A) Increases the transcription of structural genes - B) Prevents the transcription of structural genes - C) Binds to the ribosome - D) Activates RNA polymerase 24. **Which type of gene transfer involves a donor and recipient cell that are typically of the same species?** - A) Vertical gene transfer - B) Transposition  - C) Horizontal gene transfer - D) None of the above --- ### Answer Key 1. **B** - The total genetic makeup of an organism 2. **B** - Rosalind Franklin 3. **A** - Thymine 4. **B** - DNA helicase 5. **C** - Synthesizing a new strand by adding nucleotides 6. **B** - In the cytoplasm 7. **C** - RNA contains uracil instead of thymine 8. **B** - It carries the genetic code from DNA to the ribosome 9. **C** - tRNA 10. **D** - Both A and B 11. **B** - Methionine 12. **B** - The end of translation 13. **C** - It is inducible and activated in the presence of lactose 14. **C** - Constitutive 15. **A** - Mutation 16. **D** - Nonsense mutation 17. **B** - Nucleotide excision repair 18. **B** - Test for mutagenic properties of chemicals 19. **B** - Transfer of genes between cells of the same generation 20. **A** - Physical contact between donor and recipient 21. **C** - Transcription 22. **B** - A viral vector 23. **B** - Prevents the transcription of structural genes 24. **A** - Vertical gene transfer --- --- ### Chapter 6: Microbial Genetics Continued 41. **Which type of mutation involves the insertion or deletion of nucleotides?** - A) Point mutation - B) Frameshift mutation - C) Silent mutation - D) Missense mutation 42. **What is the role of DNA ligase in DNA replication?** - A) Unwinding the DNA double helix - B) Synthesizing new DNA strands - C) Joining Okazaki fragments - D) Proofreading the newly synthesized DNA 43. **Which process involves the uptake of naked DNA by a bacterial cell?** - A) Transduction - B) Transformation - C) Conjugation - D) Transposition 44. **In the lac operon, what happens when lactose is present?** - A) The repressor binds to the operator. - B) The operon is repressed. - C) The repressor is inactivated. - D) RNA polymerase cannot bind to the promoter. 45. **What is the purpose of the Ames test?** - A) To test for DNA replication efficiency - B) To identify potential mutagens - C) To measure protein synthesis - D) To determine the genetic code 46. **Which enzyme is responsible for proofreading DNA during replication?** - A) Helicase - B) DNA polymerase - C) Primase - D) Ligase 47. **What is a primary difference between prokaryotic and eukaryotic transcription?** - A) Prokaryotic transcription occurs in the cytoplasm; eukaryotic transcription occurs in the nucleus. - B) Eukaryotic transcription requires a primer; prokaryotic does not. - C) Prokaryotic RNA undergoes splicing; eukaryotic RNA does not. - D) Eukaryotic RNA polymerase has a higher error rate than prokaryotic RNA polymerase. 48. **Which of the following codons serves as the start codon in protein synthesis?** - A) UAA - B) UAG - C) AUG - D) GCU 49. **In genetic terms, what does the term "locus" refer to?**  - A) The specific location of a gene on a chromosome - B) The entire set of genes in an organism - C) The observable traits of an organism - D) The physical structure of DNA 50. **Which of the following statements about operons is FALSE?** - A) Operons can be inducible or repressible. - B) Operons are only found in eukaryotic cells. - C) An operon contains structural genes and regulatory elements. - D) The lac operon is an example of an inducible operon. --- ### Answer Key for Continued Quiz 41. **B** - Frameshift mutation 42. **C** - Joining Okazaki fragments 43. **B** - Transformation 44. **C** - The repressor is inactivated. 45. **B** - To identify potential mutagens 46. **B** - DNA polymerase 47. **A** - Prokaryotic transcription occurs in the cytoplasm; eukaryotic transcription occurs in the nucleus. 48. **C** - AUG 49. **A** - The specific location of a gene on a chromosome 50. **B** - Operons are only found in eukaryotic cells. --- Here's a multiple-choice quiz based on the questions and topics you provided. Each question includes options, and the correct answer is indicated at the end. --- ### Quiz on Microbial Genetics #### 1. A gene is ___ - A) a fundamental unit of heredity - B) a site on a chromosome - C) a segment of DNA that codes for a protein - D) all of the above **Correct Answer: D** --- #### 2. Match the base with its appropriate pair: -A→ -T→ -G→ -C→ - 1) A - 2) T - 3) C - 4) G - 5) U - **Answer Key:** - A → 4) T - T → 3) A - G → 1) C - C → 2) G --- #### 3. Define the term, “semiconservative replication.” - A) Each new DNA molecule consists of one original and one new strand. - B) DNA replication occurs only in the presence of RNA. - C) All DNA is replicated without any errors. - D) DNA replication involves the complete separation of strands. **Correct Answer: A** --- #### 4. Describe the function of each of the following: mRNA, tRNA, rRNA - A) mRNA carries the genetic code; tRNA brings amino acids; rRNA is part of the ribosome. - B) mRNA synthesizes proteins; tRNA carries nucleotides; rRNA functions in DNA replication. - C) mRNA is a structural component; tRNA carries genetic information; rRNA transports amino acids. - D) mRNA stores genetic material; tRNA forms ribosomes; rRNA helps in DNA repair. **Correct Answer: A** --- #### 5. The enzyme ______ directs transcription. ? - A) DNA polymerase - B) RNA polymerase - C) Ligase - D) Primase **Correct Answer: B** --- #### 6. True/False: More than one codon can exist for an amino acid. **Correct Answer: True** --- #### 7. Compare and contrast bacterial and eukaryotic transcription and translation. - A) Both occur in the nucleus in eukaryotes and the cytoplasm in bacteria. - B) Eukaryotic transcription involves introns; bacterial transcription does not. - C) Bacterial transcription uses multiple RNA polymerases; eukaryotic uses one. - D) Both processes are identical in eukaryotes and bacteria. **Correct Answer: B** --- #### 8. What are the three important features of the lac operon? - A) Structural genes, operator, and promoter - B) Regulatory genes, repressor, and inducer - C) Introns, exons, and terminators - D) Genes, codons, and anticodons **Correct Answer: A** --- #### 9. What event triggers induction of the lac operon? - A) Absence of glucose - B) Presence of lactose - C) High levels of cAMP - D) Inhibition by the repressor **Correct Answer: B** --- #### 10. Describe the differences between an inducible and a repressible operon. - A) Inducible operons are active in the presence of a substrate; repressible operons are active until turned off. - B) Inducible operons are always active; repressible operons are only active when needed. - C) Inducible operons require energy to function; repressible operons do not. - D) There is no difference between them. **Correct Answer: A** --- #### 11. What are the three ways that bacteria horizontally share genes? - A) Transformation, transduction, conjugation - B) Transcription, translation, replication - C) Mutation, selection, adaptation - D) Fusion, division, differentiation **Correct Answer: A** --- #### 12. What is the difference between F factor transfer and Hfr transfer? - A) F factor transfer involves plasmid transfer; Hfr involves chromosomal DNA. - B) F factor transfer occurs only in eukaryotes; Hfr transfer occurs in prokaryotes. - C) F factor transfer is less efficient than Hfr transfer. - D) There is no difference between the two. **Correct Answer: A** --- #### 13. A cell must be _____ in order to be transformed. ? - A) Competent - B) Active - C) Living - D) Eukaryotic **Correct Answer: A** --- #### 14. _______ are involved in transduction. ? - A) Plasmids - B) Viruses - C) Ribosomes - D) Endosomes **Correct Answer: B** --- #### 15. The formal name for “jumping genes” is ______. ? - A) Introns - B) Exons - C) Transposons - D) Codons **Correct Answer: C** --- #### 16. True/False: A spontaneous mutation arises from exposure to chemicals or physical agents. **Correct Answer: False** --- #### 17. A(n) ______ mutation results in a stop codon. ? - A) Missense - B) Nonsense - C) Silent - D) Frameshift **Correct Answer: B** --- #### 18. A(n) ______ mutation nearly always results in a nonfunctional protein. ? - A) Silent - B) Missense - C) Nonsense - D) Frameshift **Correct Answer: D** --- #### 19. The ______ is a first-line screening technique to detect mutagenic chemicals. ? - A) Ames test - B) PCR - C) Southern blot - D) Northern blot **Correct Answer: A** --- #### 20. True/False: Mutations are always harmful to organisms. **Correct Answer: False** --- Here’s a multiple-choice quiz based on Chapter 7: Viruses, covering the key concepts and terminology outlined in your study guide. --- ### Quiz on Viruses #### 1. Which of the following is a characteristic of viruses? - A) Cellular structure - B) Ultramicroscopic size - C) Capable of independent reproduction - D) All of the above **Correct Answer: B** --- #### 2. What distinguishes viruses from cellular organisms? - A) Viruses contain ribosomes. - B) Viruses are larger than bacteria. - C) Viruses cannot reproduce independently. - D) Viruses have cell membranes. **Correct Answer: C** --- #### 3. What is the measurement unit commonly used for viruses? - A) Micrometers - B) Nanometers - C) Millimeters - D) Centimeters **Correct Answer: B** --- #### 4. What factors control the infectious properties of viruses? - A) Size and shape - B) Host range and receptor specificity - C) Mode of replication - D) All of the above **Correct Answer: B** --- #### 5. How would you culture viruses? - A) On agar plates - B) In a nutrient broth - C) In living host cells - D) On a microscope slide **Correct Answer: C** --- #### 6. Which of the following are components of a virus? - A) Capsid - B) Nucleic acid - C) Envelope - D) All of the above **Correct Answer: D** --- #### 7. What kinds of nucleic acids can viruses have? - A) Only DNA - B) Only RNA - C) Both DNA and RNA - D) Neither DNA nor RNA **Correct Answer: C** --- #### 8. Which statement is true regarding +RNA and -RNA viruses? - A) +RNA can be directly translated into proteins; -RNA must first be converted to +RNA. - B) -RNA can be directly translated into proteins; +RNA must first be converted to -RNA. - C) Both types can be directly translated into proteins. - D) Neither can be translated into proteins. **Correct Answer: A** --- #### 9. What is the primary structure of a virus's capsid made up of? - A) Lipids - B) Proteins called capsomeres - C) Nucleic acids - D) Carbohydrates **Correct Answer: B** --- #### 10. Which of the following diseases is caused by a virus? - A) Tuberculosis - B) Malaria - C) Influenza - D) Syphilis **Correct Answer: C** --- #### 11. What are cytopathic effects (CPEs)? - A) Symptoms of a viral infection - B) Visible changes in host cells due to viral replication - C) Mechanisms of viral entry into cells - D) Types of viral structures **Correct Answer: B** --- #### 12. During viral replication, which phase involves the synthesis of viral components? - A) Adsorption - B) Penetration - C) Synthesis - D) Release **Correct Answer: C** --- #### 13. How do enveloped viruses differ from naked viruses during replication? - A) Enveloped viruses do not have a nucleic acid. - B) Enveloped viruses acquire their envelope from the host cell membrane. - C) Naked viruses replicate in the nucleus only. - D) There is no difference; both types replicate the same way. **Correct Answer: B** --- #### 14. What is the primary difficulty in treating viral infections in humans? - A) Viruses do not have a cellular structure. - B) Antibiotics are effective against viruses. - C) Viruses replicate independently of host cells. - D) Vaccines can cause viral infections. **Correct Answer: A** --- #### 15. What are the general characteristics of bacteriophages? - A) They infect animal cells. - B) They have a complex structure including a head and tail. - C) They are larger than most animal viruses. - D) They are acellular. **Correct Answer: B** --- #### 16. Which term describes a viral DNA integrated into a bacterial chromosome? - A) Provirus - B) Prophage - C) Latent virus - D) Virion **Correct Answer: B** --- #### 17. What occurs during the lytic cycle of a bacteriophage? - A) Viral DNA integrates into the host genome. - B) The host cell is lysed, releasing new virions. - C) The virus enters a dormant phase. - D) The host cell reproduces normally. **Correct Answer: B** --- #### 18. How do bacteriophage multiplication and animal virus multiplication differ? - A) Bacteriophages replicate in the cytoplasm; animal viruses replicate in the nucleus. - B) Bacteriophages do not have an envelope; animal viruses may have one. - C) Both are identical in their replication processes. - D) A and B are correct. **Correct Answer: D** --- #### 19. What are satellite viruses? - A) Viruses that can replicate independently. - B) Smaller viruses that require a helper virus for replication. - C) Viruses that infect bacteria. - D) Viruses that can infect multiple hosts. **Correct Answer: B** --- #### 20. What are viroids? - A) Infectious agents made of protein only. - B) Small, circular RNA molecules that infect plants. - C) Bacterial viruses. - D) Large DNA viruses that infect animals. **Correct Answer: B** --- #### 21. Which of the following is a key difference between viruses and cells? - A) Viruses have a cell membrane. - B) Viruses can metabolize nutrients. - C) Viruses do not have ribosomes for protein synthesis. - D) Viruses reproduce by binary fission. **Correct Answer: C** --- #### 22. What is a "lysogenic" cycle? - A) A viral replication cycle that leads to cell lysis immediately. - B) A cycle where the viral genome integrates into the host genome and remains dormant. - C) A cycle that only occurs in animal viruses. - D) A method of bacterial reproduction. **Correct Answer: B** --- #### 23. Which of the following statements is true about the RNA genome of retroviruses? - A) They replicate their RNA directly to produce proteins. - B) They convert their RNA into DNA using reverse transcriptase. - C) They contain only positive-sense RNA. - D) They do not use host cell machinery for replication. **Correct Answer: B** --- #### 24. In which phase of the viral multiplication cycle does the virus attach to the host cell? - A) Penetration - B) Assembly - C) Release - D) Adsorption **Correct Answer: D** --- #### 25. What role do host range and specificity play in viral infections? - A) They determine how viruses replicate. - B) They affect the types of cells a virus can infect. - C) They influence the symptoms of the infection. - D) They do not play a significant role in viral infections. **Correct Answer: B** --- #### 26. Which type of virus can cause cancer? - A) Lytic viruses - B) Bacteriophages - C) Oncogenic viruses - D) Non-enveloped viruses **Correct Answer: C** --- #### 27. What is the term for a virus that infects bacteria? - A) Retrovirus - B) Viroid - C) Bacteriophage - D) Prion **Correct Answer: C** --- #### 28. What is the primary method used for preventing viral infections in humans? - A) Vaccination - B) Antibiotics - C) Antifungal medications - D) Dietary supplements **Correct Answer: A** --- #### 29. What is the purpose of the viral capsid? - A) To provide energy for the virus - B) To protect the viral genome and facilitate entry into host cells - C) To replicate the viral genome - D) To act as a receptor for host cells **Correct Answer: B** --- #### 30. Which of the following is NOT a characteristic of viroids? - A) They are smaller than viruses. - B) They consist of single-stranded RNA. - C) They infect animal cells. - D) They lack a protein coat. **Correct Answer: C** --- #### 31. How do persistent infections differ from acute infections? - A) Persistent infections have a rapid onset; acute infections last longer. - B) Acute infections cause immediate symptoms; persistent infections can remain asymptomatic. - C) Persistent infections are always caused by retroviruses. - D) There is no difference between the two. **Correct Answer: B** --- #### 32. What is meant by the term "provirus"? - A) The inactive form of a virus in the environment. - B) A viral genome that has integrated into the host cell's DNA. - C) A viral particle that is released from a host cell. - D) A viral infection that causes rapid cell death. **Correct Answer: B** --- #### 33. Which of the following viruses is known for causing chickenpox and shingles? - A) Influenza virus - B) Varicella-zoster virus - C) Rabies virus - D) Human immunodeficiency virus **Correct Answer: B** --- #### 34. The term "lysogenic conversion" refers to: - A) The process of viral replication leading to cell lysis. - B) A change in the host phenotype due to viral genes. - C) The ability of a virus to replicate without a host. - D) The transformation of RNA into DNA in retroviruses. **Correct Answer: B** --- #### 35. What are the structural components of a bacteriophage? - A) Envelope, capsid, and ribosomes - B) Capsid, tail fibers, and nucleic acid - C) Cell wall and membrane - D) Mitochondria and nucleus **Correct Answer: B** --- #### 36. What is the primary function of tRNA in protein synthesis? - A) To carry genetic information from DNA to ribosomes - B) To deliver amino acids to ribosomes during translation - C) To synthesize ribosomal RNA - D) To splice introns from mRNA **Correct Answer: B** --- #### 37. Which statement is true about the viral envelope? - A) It is present in all viruses. - B) It is composed of nucleic acids. - C) It is derived from the host cell's membrane. - D) It plays no role in viral entry into cells. **Correct Answer: C** --- #### 38. Which of the following processes allows genetic material to be exchanged between bacteria? - A) Transcription - B) Transformation - C) Translation - D) Transduction **Correct Answer: B** --- #### 39. What is the main challenge in developing antiviral drugs? - A) Viruses have a complex structure. - B) Viruses use host cell machinery for replication. - C) Viruses mutate too quickly. - D) All of the above. **Correct Answer: D** --- #### 40. What is the role of reverse transcriptase in retroviruses? - A) To translate RNA into proteins - B) To convert viral RNA into DNA - C) To replicate DNA into RNA - D) To integrate viral DNA into the host genome **Correct Answer: B** --- --- ### Prions and Viruses Quiz #### 1. What are prions? - A) Infectious proteins that cause neurodegenerative diseases - B) Types of bacteria that cause infections - C) A type of virus with a DNA genome - D) Parasitic organisms that infect cells **Correct Answer: A** --- #### 2. How are prions different from viruses? - A) Prions contain nucleic acids, while viruses do not. - B) Prions are composed only of protein, whereas viruses contain nucleic acids and proteins. - C) Prions can be treated with antibiotics, while viruses cannot. - D) Prions are larger than viruses. **Correct Answer: B** --- #### 3. Which of the following diseases is caused by prions? - A) Influenza - B) Mad Cow Disease - C) HIV/AIDS - D) Chickenpox **Correct Answer: B** --- #### 4. True/False: It is best to describe viruses as alive or dead. - A) True - B) False **Correct Answer: B** --- #### 5. What are the characteristics of viruses that distinguish them from cellular life? - A) They contain DNA and RNA. - B) They lack cellular structure and metabolic processes. - C) They can reproduce independently. - D) They have ribosomes for protein synthesis. **Correct Answer: B** --- #### 6. True/False: Viruses can be seen with a light microscope. - A) True - B) False **Correct Answer: B** --- #### 7. Viral capsids are constructed from ______ subunits. - A) DNA - B) RNA - C) Capsomeres - D) Glycoproteins **Correct Answer: C** --- #### 8. Describe the structures of icosahedral, helical, and complex viruses. - A) Icosahedral viruses have spherical shapes; helical viruses have rod shapes; complex viruses have irregular shapes. - B) Icosahedral viruses have rod shapes; helical viruses are spherical; complex viruses are all enveloped. - C) Icosahedral viruses are always larger than helical viruses; complex viruses have simple structures. - D) All viruses have the same structure regardless of type. **Correct Answer: A** --- #### 9. List three unique forms of viral nucleic acid. - A) Circular DNA, linear RNA, and segmented RNA - B) Single-stranded RNA, double-stranded DNA, and protein - C) Plasmid DNA, ribosomal RNA, and mRNA - D) Only DNA **Correct Answer: A** --- #### 10. Standard virus classification systems use all of the following except ______. - A) Genetic makeup - B) Structure - C) Disease caused - D) Chemical composition **Correct Answer: D** --- #### 11. A virus name ending in –viridae denotes a viral ______. - A) Genus - B) Family **Correct Answer: B** --- #### 12. List and describe the main steps of animal virus replication. - A) Adsorption, penetration, uncoating, biosynthesis, maturation, and release. - B) Attachment, reproduction, transformation, and lysis. - C) Infection, multiplication, and dormancy. - D) Entry, integration, and exit. **Correct Answer: A** --- #### 13. What is the difference between DNA virus replication and RNA virus replication? - A) DNA viruses replicate in the cytoplasm; RNA viruses replicate in the nucleus. - B) DNA viruses use reverse transcriptase; RNA viruses do not. - C) RNA viruses must be translated immediately; DNA viruses can integrate into the host genome. - D) There is no difference; they replicate the same way. **Correct Answer: C** --- #### 14. True/False: Viruses that infect animal cells can never infect human cells. - A) True - B) False **Correct Answer: B** --- #### 15. Describe the differences between the lytic and lysogenic phases of viral replication. - A) Lytic phases cause immediate cell destruction; lysogenic phases integrate into host DNA. - B) Lytic phases are only seen in bacteriophages; lysogenic phases occur in animal cells only. - C) Both phases result in the same outcome for the host cell. - D) Lytic phases involve no latency; lysogenic phases cause rapid cell death. **Correct Answer: A** --- #### 16. Describe the primary purposes of viral cultivation. - A) To study their effects on bacteria. - B) To understand their genetics and develop vaccines. - C) To create new antibiotics. - D) To enhance food preservation techniques. **Correct Answer: B** --- #### 17. The influenza virus has traditionally been cultured in ______. - A) Bacteria - B) Chicken eggs - C) Plant tissue - D) Yeast **Correct Answer: B** --- #### 18. Describe the difference between primary and continuous cell lines. - A) Primary cell lines are immortalized; continuous cell lines are derived from tumors. - B) Primary cell lines can be subcultured indefinitely; continuous cell lines cannot. - C) Primary cell lines are derived from normal tissues; continuous cell lines can be subcultured indefinitely. - D) There is no difference; they are the same. **Correct Answer: C** --- #### 19. True/False: The term plaques is only used to describe the effects of bacteriophage on cell cultures. - A) True - B) False **Correct Answer: A** --- #### 20. True/False: Viral infections are more common than bacterial infections. - A) True - B) False **Correct Answer: A** --- #### 21. True/False: Viral mutation rates are low and viruses are easy to track in a population. - A) True - B) False **Correct Answer: B** --- #### 22. Doctors and scientists most often rely on ______ to treat or prevent viral infections: - A) Antibiotics - B) Antiviral drugs - C) Vaccines - D) Herbal remedies **Correct Answer: C** --- #### 23. Prions are composed of ______. - A) DNA - B) RNA - C) Protein - D) Polysaccharide **Correct Answer: C** --- #### 24. Satellite viruses require ______ in order to multiply. - A) Host cells - B) Other viruses - C) Bacteria - D) RNA **Correct Answer: B** --- #### 25. ______ infect plants. - A) Prions - B) Satellite viruses - C) Viroids - D) Retroviruses **Correct Answer: C** ---