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120 Cards in this Set
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Nutrition
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Process by which chemical substances (nutrients) are acquired by the environment and used in cellular activities like metabolism and growth.
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Essential nutrient
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Any substance that must be provided to an organism
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Two categories of essential nutrients are?
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Macro
Micro nutrients |
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Macronutrient
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- Required in large qts
- Principal roles in cell structure and metabolism - Carbon, hydrogen, oxygen, |
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Micronutrient
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Trace elements
- Manganeses, zinc, nickel - smaller amts. - varies |
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Heterotroph
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- Obtains carbon in an organic form made by OTHER LIVING ORGANISMS
e.g. proteins, carbs, lipids, nucleic acids |
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Autotroph
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An organism using CO2, an inorganic gas, as its carbon source
- not nutritionally dependent on other living things |
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Requirements for Growth:
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1. Physical (temp, pH, osmotic pressure)
2. Chemical (water, carbon, nitrogen, minerals, oxygen, organic growth factors) 3. Temperature |
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Why are organisms particular to a pH?
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Enzymes denature at certain pHs. (It affects metabolism).
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3 primary groups of Temperature
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1. Psychrophiles
2. Mesophiles 3. Thermophiles |
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Most bacteria favor which temperature?
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- Human body temp
- Mesophile (2nd temp group) |
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Nutritional Types: Main determinants of nutritional type are?
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1. Carbon source
2. Energy source |
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2 Types of energy sources
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Chemotroph - from chemical compounds
Phototroph - through photosynthesis |
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Why is oxygen impt as a factor affecting microbes?
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Amt of oxygen determines how much ATP produced.
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Environmental factors affecting the function of metabolic enzymes.
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Temperature, Oxygen requirements, pH, Osmotic pressure, Barometric pressure
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Table 7.4
Photoautroph examples include |
Algae, plants, cyanobacteria
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Table 7.4
Chemoautotroph examples include |
Only certain bacteria, such as methanogens, deep-sea vent bacteria
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Table 7.4
Chemoheterotroph |
Protozoa, fungi, many bacteria, animals
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Table 7.4
Saprobe |
Fungi, bacteria (decomposers)
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Table 7.4
Parasite |
Various parasites and pathogens; can be bacteria, fungi, protozoa, animals
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Table 7.4
Photoheterotroph examples.... |
Purple and green photosynthesis bacteria
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Regarding temperature,
Describe Psychrophiles. |
Max temperature below 15 C
Min temp less than -15 C |
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Regarding temperature,
describe Mesophiles. |
Optimun temp 37 C; most human pathogens
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Regarding temperature,
describe Thermophiles. |
Optimum temp 70 C
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Gas Requirements (Oxygen) 3 points
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1. As oxygen is used it is transformed into several toxic products. [peroxide, hydroxyl radicals]
2. Most cells have developed enzymes that neutralize these chemicals: [superoxide dismutase, catalase] 3. If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats. |
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Categories of Oxygen Requirement (3 main groups)
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1. Aerobe
2. Facultative anaerobe 3. Anaerobe |
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Aerobe (category of oxygen requirement)
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- Uses oxygen and can detoxify it
a. Obligate aerobe - cannot grow without oxygen b. Microaerophilic - requires only a small amt of oxygen. |
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Facultative anaerobe
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Uses oxygen but can also grow in its absence
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Anaerobe (2 subgroups)
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- Does not use oxygen
a. Obligate = lacks enzymes to detoxify oxygen so cannot survive in an oxygen environment b. Aerotolerant = does not utilize oxygen but can survive and grow in its presence |
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Why doesn't hydrogen peroxide work effectively on scrapes?
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Because the bacteria neutralizes the chemicals with catalase. (see bubbles)
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2 Major Transport processes in cells
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Passive
Active |
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Passive transport
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No energy expenditure required.
Concentration gradient. |
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2 forms of passive transport
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Diffusion - random motion
Facilitated diffusion - binds to a carrier protein in membrane and is carried across |
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Active transport
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Energy expended. No need for gradient. Transport rate increased. May occur against a concentration gradient.
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Active transport (1 Type)
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Carrier-mediated active transport - atoms/molecules are pumped into or out of the cell by specialized receptors. Driven by ATP or the proton motive force.
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Temperature adaptive groups (3)
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Psychrophiles
Mesophiles Thermophiles |
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Temp adaptive group: Psychrophiles
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- Can grow at or near 0 C.
- Have an optimum below 15 C |
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Temp adaptive group: Mesophile
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- Can grow between 10 C and 50 C
- Optima btwn 20-40 C |
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Temp adaptive group: Thermophile
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- Require temp above 45 C - 80 C
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Figure 7.11 - Demonstration of oxygen requirements.
Describe what was shown. (Recall Tube 1, 2, 3, 4) |
- Oxygen concentration is highest at the top of the tube.
- When a series of tubes is inoculated with bacteria that differ in O2 requirements, the relative position of growth provides some indication of their adaptations to oxygen use. |
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Fig. 7. 11
Tube 1 - White layer at top. Clear throughout. Describe it. |
Aerobic.
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Fig. 7.11
Tube 2 - White layer with upper half mixed white and lower cloudy. |
Facultative anaerobes
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Fig. 7.11
Tube 3 - Top white layer with cloudiness throughout. |
Facultative anaerobe.
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Fig. 7.11
Tube 4 - No top white layer. Cloudy in middle to bottom. |
Obligate anaerobe.
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Effects of pH (3 points)
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- Majority of microorgas grow btwn pH 6-8
- Obligate acidophiles - grow at extreme acid pH - Obligate Alkalinophiles - grow at extreme alkaline pH |
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Osmotic Pressure (3 points)
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- Most microbes exist under hypotonic or isotonic conditions
- Halophiles - require a high concentration of salt - Osmotolerant - do not require high concentration of solute but can tolerate it when it occurs |
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Capnophiles
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Microbes that grow best at higher CO2 tensions than are normally present in the atmosphere
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Ecological Associations:
2 Major Classes |
Symbiotic
Nonsymbiotic |
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Symbiotic relationship
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aka symbiosis
Organism living in close nutritional relationsihps; required by one or both members |
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Nonsymbiotic relaitonship
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Organisms are free-living relationships
not required for survival. |
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3 subgroups of Symbiosis
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Mutualism
Commensalism Parasitism |
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Mutualism
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Obligatory, dependent. Both members benefit.
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Commensalism
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Commensal benefits
Other member not harmed. |
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Parasitism
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Parasite is dependent and benefits; host harmed.
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Nonsymbiotic subgroups (2).
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Synergism
Antagonism |
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An example of Mutualism.
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Intestinal flora.
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An example of commensalism
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Vectors
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An example of Parasitism.
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Hookworm
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Several examples of Aerobes.
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Staphylococcus growing on skin.
Mold growing on orange. Bathroom mold. Epidermophyte microsporum. |
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Examples of Anaerobes.
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Staph growing inside bone tissue.
Clostridium tetanii in the soil. |
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Everything that an organism does is dependent on ......?
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Enzymes (and pH)
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Regarding osmotic pressure, fungi tend to have higher osmotic pressure resistance than ?
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Bacteria.
Ex: They can grow in high fructose corn syrups but not bacteria. Just like adding salt to canned goods. |
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Interrelationships Btwn Microbes and Humans
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Human body is a rich habitat for symbiotic bacteria, fungi, and a few protozoa = normal microbial flora
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Describe the relationship between bacteria and yeast in the vagina.
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They BALANCE each other!
If one overgrows > infection |
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How do microbes control their different populations in the body?
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Producing fungicins and bacteriocins preventing overgrowth of their surroundings.
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The division of a bacterial cell occurs mainly through what?
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Binary fission
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Microbial Growth
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# of cells, NOT the cells' size
Hundreds of thousands increase |
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The Study of Microbial Growth (2 levels)
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Growth occurs at 2 levels:
1 - Growth at a cellular level with increase in size 2 - Increase in population |
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Binary fission process
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Parent cell enlarges, duplicates its chromosomes, forms a central transverse septum dividing the cell into 2 daughter cells
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Fission cycle is also known as what?
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Generation time
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Rate of population growth (3 points)
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Time required for a complete fission cycle = generation/doubling time.
Each new fission cycle increases the population by a factor of 2. Generation times vary from minutes to days. |
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Generation time: The number of cells in each generation is expressed as ?
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a power of 2.
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The number of generations is the ?
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Exponent
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Each cell in a generation produces how many cells?
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2 cells
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If an organism has a short generation time, then it is ?
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More communicable
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Generation time scenario:
If a bacterium reproduces every 10 minutes, how many cells would you have at the end of 1 hour? |
Solution: 64 cells
2^6 = 64 64 cells |
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Scenario 2: If you had 4 million cells on a piece of chicken....how many would you have at the end of 1 hour? 2 hours? If you had generation times of 20 minutes?
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Solution;
a. 2^3 = 8 8 x 4 mil = 32 mill b. 2^6 = 64 64 X 4 mill = 256 mill |
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Bacteria STOPS growth at what temperature?
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10 degrees centigrade
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Population Growth Curve Stages (4)
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Lag phase
Exponential growth phase Stationary phase Death phase |
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Lag phase
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"Flat" period of adjustment, enlargement; little growth
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Exponential growth phase
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A period of maximum growth will continue as long as cells have adequate nutrients and a favorable environment
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Stationary phase
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Rate of cell growth equals rate of cell death caused by depleted nutrients and O2, excretion of organic acids and pollutants.
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Death phase
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As limiting factors intensify, cells die exponentially
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Methods of Analyzing Population Growth
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1. Turbidometry (most simple)
2. Viable Cell Count 3. Direct cell count |
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What is turbidometry?
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Degree of cloudiness (turbidity) reflecting the relative population size.
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What is Direct Cell Count?
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Counting the number of cells microscopically.
- Use a cytometer (no distinction between dead/live cells) - Coulter counter - electronically scansa culture as it passes thru tiny pipette. - Actual count from petri dish using a chart |
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An organic nutrient essential to an organism's metabolism that cannot be synthesized itself is termed a/an ?
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Growth factor
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Source of the necessary elements of life is ?
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An inorganic environment reservoir
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An organism that can synthesize all its required organic components from CO2 using energy from the sun is a....?
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Photoautotroph
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An obligate halophile requires high what?
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Salt
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Chemoautrotrophs can survive on _____ alone.
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Minerals and CO2
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Which of the following statements is true for all organisms?
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They require inorganic nutrients.
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A pathogen would most accurately be described as a ?
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Parasite
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Which of the following is true of passive transport?
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Requires a gradient
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A cell exposed to a hypertonic environment will _____ by osmosis.
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Lose water.
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Active transport of a substance across a membrane requires ?
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ATP expenditure
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Psychrophiles would be expected to grow ?
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At refrigeration temperatures.
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Superoxide ion is toxic to strict anaerobes because they lack what?
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Dismutase
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The time required for a cell to undergo binary fission is called the ?
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Generation time
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In a viable plant count, each _____ represents a _____ from the sample population.
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Colony/Cell
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The stage in population growth with the highest rate of cell division is the ?
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Log phase
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Extremophiles are most commonly what type of microorganism?
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Archae
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Substances required by living organisms in relatively large quantities and which play principle roles in cell structure and metabolism are known as what?
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Macronutrients
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Which of the following defines a heterotroph?
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An organism that must obtain its carbon in an organic form.
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Molecules that satisfy heterotrophic nutritional requirements include all but which of the following? (Water, Lipids, nucleic acids, carbs, proteins)
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Water
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Nitrogen is required for the production of what category of molecules?
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Nucleotides
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The primary sources of nitrogen for heterotrophs include all except which of the following? (Proteins, DNA, RNA, Glucose, Amino acids)
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Glucose
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What nutritional category of microorganisms plays an important part in recycling inorganic nutrients?
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Chemoautotrophs
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The principal energy-yielding reaction in animals, most protozoa and fungi, and aerobic bacteria is known as what?
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Aerobic Respiration
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The earth would gradually fill up with organic material, and nutrients would not be recycled if it were not for what group of organisms?
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Saprobes
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The more successful of the parasitic microorganisms have what type of effect on their host?
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They have no fatal effects on the host and eventually evolve to a less harmful relationship with the host.
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Osmosis requires that a membrane have what property?
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Be selectively permeable to molecules other than water
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The most stable environment for cells exists in what type of solution
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Isotonic
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What is not a feature inherent in active transport systems?
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They form energy during transport.
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For most microbes, environmental factors fundamentally affect the function of what?
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Enzymes
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How is Taq polymerase from Thermus aquaticus able to function when used in the polymerase chain reaction?
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Its a heat-stable enzyme.
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What form of oxygen is not toxic to microorganisms?
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O2
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Which of the following describes anaerobic organisms?
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They lack the enzymes that use oxygen in metabolism and they lack the enzymes that process toxic oxygen products.
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Microorganisms that are sometimes found growing in jellies, syrups, and brines are known as what?
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Osmophiles
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Bacteria divide by a process known as what?
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Binary fission
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