Exam (elaborations)
BIO 260 Exam 2 Detailed Questions And Expert Answers
- Course
- BIOLOGY 260
- Institution
- University Of Minnesota - Crookston
BIO 260 Exam 2 Detailed Questions And Expert Answers
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BIO 260 Exam 2 Detailed Questions And ExpertAnswers
1. Understand what is meant by generation time, and binary fission. Do all
organisms have the same generation time? Be able to use the formula on p. 93 to
calculate the number of cells in a population after a given amount of time. - ANS -
generation time: the time it takes for a cell to divide once
-Binary fission: the way in which bacteria split to multiply
-Organisms differ in the generation time
-N^t=Nv0X2^n
example: starting with 10 cells with a generation time of 20 minutes. calculate how
many there will be after two hours.
10x2^6=640
2. What is a biofilm? What are some medical applications/examples of biofilms?
Are all biofilms damaging - ANS Biofilm: slimy matrix in which multiple bacterium
live.
biofilms can cause persistent ear infections and tooth decay
biofilms are encouraged in sewer treatment facilities.
3. What is the definition of a pure culture? What are some techniques used to
determine if a sample is pure? How are stock cultures maintained? - ANS -pure
culture: a sample consisting only of one type of bacteria.
-streak plate is a technique used for pure samples.
, - pure cultures that you want to keep for future use. They are refrigerated on and
agar slant or frozen for long-term storage
4. Explain how physical conditions such as temperature, pH, and oxygen can
influence bacterial growth. - ANS Temp: can have an influence on the speed of
growth (including optimum growth), and too hot of temp can kill some bacteria.
pH: bacteria that are not adapted to live in acidic conditions will die when their
proteins denature.
O2: some bacteria require O2, some require the absence of O2, and others can
survive in either anaerobic or aerobic conditions.
H20: some bacteria require a specific water condition (less or more osmotic) to
survive.
5. What is the optimum temperature for growth of psychrophiles, psychrotrophs,
mesophiles, and thermophiles? - ANS psychophiles: -5-15 C
psychotrophs: 15-30 C
mesophile: 25-45 C
thermophile: 45-70 C
Hyperthermophile: 70+ C
6. What are the basic chemical requirements for bacterial growth? - ANS Carbon
oxygen
hydrogen
nitrogen
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