MicroBiology- Unit 1 Homework Questions

Father Spallazani repeated John Needham's experiment but Spallazani boiled the broth for much longer and sealed the flasks by melting their necks closed. He observed that the broth remained sterile, basically forever. What do you think the vast majority of the people believe from his experiment? a. life must beget other life-living things come from other living things b. because the flask of broth was sealed, the vital forces of life could not enter the flask c. because he boiled the broth for too long, the vital forces of life were destroyed

b

John Needham designed an experiment in which he boiled some broth and then corked the flask it was in, thereby sealing the flask. After a few days, he noticed that the broth had microbes in it! What did people conclude from Needham's experiment? a. spontaneous generation of small things like microbes still occur b. spontaneous generation cannot occur in boiled broths c. microbes can penetrate cork and/or glass

a

Which of the following are examples of biofilm Check All That Apply a.Dental plaque. b. Scum accumulating in toilet bowls. c. Slipperiness on rocks in stream beds. d. Capsule formation around Streptococcus pneumoniae. e. Furry grayish-white growth on old bread or fruit.

a, b, c

1. Both human cells and bacterial cells divide by mitosis. True or False 2. Cells must ______ their DNA prior to cell division. a. replicate b. translate c. denature d. transcribe e. hydrolyze 3. Environmental factors control microbial growth through their effect on enzyme activity. True or False

1. False 2. a 3. True

1. John Needham's experiment was clever and well accepted by the scientific community during his time because ______. a. his method of "cooking" the broths was how they normally cooked during that time. b. he used a cork and broth, items that most people used, so they trusted him. c. he was a leader in his community and people trusted everything he said. 2. What is a probable reason why corked glass jars were not suspected in the transmission of microbes? a. Many other things have been placed into jars and corked without any perceived microbial contamination. b. People knew that "vital forces" essential for life cannot penetrate glass or corks. c. Glass was well known to kill microbes, which is why people of those days hardly ever used it.

1. a 2. a

1. Most cultured bacteria tend to multiply by _____. a. sexual reproduction b. binary fusion c. binary fission d. fragmentation e. budding 2. Cell division is triggered exclusively when cells attain a threshold mass. True or False 3. DNA helicase is responsible for adding nucleotides to the growing end of the DNA. True or False

1. b 2. false 3. false

1. Francisco Redi performed an experiment in which he put meat in jars, covering some with gauze and leaving others open. He then observed the meat over a few days. While this experiment is very well known in biology, it still did not completely change everyone's belief in spontaneous generation. How was the experiment lacking? a. The cloth eventually rotted too. b. It didn't explain that the meat could still "rot". c. The glass jars were not shatter resistant. d. Maggots still formed, only much later. 2. Which of the following could be another "good" reason for the meat still rotting? a. The "vital force" required for life could still penetrate the cloth and cause the meat to spontaneously change. b. Someone changed the experiment while Redi wasn't looking, substituting fresh meat for rotting meat. c. Meat will naturally appear to rot over time, no matter how or where it is stored.

1. b 2. a

1. Prior to using microscopes, do you think most people knew of biological activities such as flies laying eggs? a. yes b. no 2. Does "spontaneous generation" make sense to people from ancient times? a. Absolutely b. Not at all

1. b 2. a

1. The FtsZ protein is needed to form the ______. a. ribosomes b. replicated DNA c. septum d. mitochondria e. All of the these 2. The energy source for contraction of the FtsZ ring during cell division comes from ______. a. the synthesis of GAP b. the hydrolysis of GTP c. the synthesis of gyrase d. the hydrolysis of ATP e. the hydrolysis of gyrase 3. Which enzyme is NOT involved in DNA replication? a. RNA polymerase b. Ligase c. Helicase d. Gyrase e. DNA polymerase 4. Cells cannot begin a new round of replication until they have completely finished dividing. True or False

1. c 2. b 3. a 4. False

1. Why were people still so unwilling to dismiss spontaneous generation even after Father Spallanzani's experiment? a.They thought Spallanzani's experiment was flawed because he boiled the broth for too long. b.People are stubborn - they know what they know and nothing can change that except a new law. c.For about 1,900 years, spontaneous generation was shown to be "true" by repeated observations. 2. What would be a "good" argument against Spallanzani's experiment and in support of spontaneous generation? a.Using too much heat during the boiling process destroyed the "vital force," preventing the generation of new life. b.The glass jar inhibited the generation of any living organisms from the boiled broth. c.Melting the flask neck closed kept the "vital forces" from entering and prevented spontaneous generation of life.

1. c 2. c

Special stain vs. differential stain vs. simple stain

Gram stain (Differential stain) Endospore stain (Special stain) Single dye staining (example: Methylene blue stain) (Simple stain)

Magnification vs. Contrast vs. Resolution *The apparent increase in size of an image. *Ability to be distinguished from the surroundings. *The ability to distinguish between two separate structures that are very close to one another.

The apparent increase in size of an image (magnification) Ability to be distinguished from the surroundings (contrast) The ability to distinguish between two separate structures that are very close to one another (resolution)

1. What about Pasteur's experimental design was uniquely directed at dismissing the notion of "vital forces" and spontaneous generation? a. The boiling point of the broth, which removed the need for "vital forces". b. The amount of time that passed before microbes were seen in the broth. c.The swan-neck flasks, which allowed "vital force" but not microbes to enter the broth.

c

You use the streak-plate method to obtain a pure culture and observe individual colonies following incubation. Consider a single bacterial colony. All of the following statements about the colony are true EXCEPT: Multiple Choice a. Cells at the middle of the colony are probably growing less actively than cells at the edges of the colony. b. All cells in the colony are genetically identical, except for any mutations that might have arisen during binary fission. c. Cells at the edges of the colony are likely experiencing a higher oxygen concentration than those in the middle of the colony. d. Nutrients slowly diffuse through the agar and feed the bacteria in the colony, and similarly, wastes from the colony slowly diffuse away. e. All cells in the colony are expressing the same set of genes and are performing the same metabolic functions.

e