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MICROBIOLOGY > EXERCISE 7 > Flashcards

EXERCISE 7 Flashcards

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Biology 101 flashcards
1
Q

What is a complex mixture of organic matter?

A

SOIL

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2
Q

4 components of soil

A

mineral particles, water, air, and organic matter

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3
Q

What microbial populations do soil contain? (4)

A

fungi
bacteria
algae
protozoa

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4
Q

What level of soil has the highest number of microorganisms

A

topsoil

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5
Q

What is the narrow soil region surrounding the plant roots?

A

Rhizosphere

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6
Q

Microbial counts decrease with…?

A

Soil Depth

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7
Q

Why does the top soil later have the highest microbial count? (3)

A

availability of ORGANIC MATTER, OXYGEN, and other NUTRIENT SOURCES

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8
Q

Particularly where in the TOP SOIL REGION is there high microbial activity

A

Rhizosphere

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9
Q

What type of bacteria can be found in the RHIZOSPHERE

A

nitrogen-fixing bacteria

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10
Q

6 factors that affect population of microorganism

A
  1. physical structure
  2. nutrient composition
  3. temperature
  4. water potential
  5. availability of oxygen
  6. pH level
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11
Q

2 types of enrichment on soil microorganisms

A
  1. urea
  2. starch
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12
Q

TYPE OF ENRICHMENT ON SOIL MICROORGANISM

nitrogenous organic compound

A

urea

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13
Q

TYPE OF ENRICHMENT ON SOIL MICROORGANISM

used as solid nitrogenous fertilizer

A

urea

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14
Q

TYPE OF ENRICHMENT ON SOIL MICROORGANISM

polysaccharide

A

starch

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15
Q

A soil rich in the ff will promote what kind of microorganism? And why?

  1. urea
  2. starch
A
  1. bacteria — has UREASE which breaks down urea
  2. molds — has AMYLASE which breaks down amylose in starch
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16
Q

5 importance of microorganisms in the soil

A
  1. weathering of rocks and soil formation
  2. decomposition of complex organic materials
  3. geo-chemical cycling of nitrogen, sulfur, carbon, and phosphorus
  4. reservoir of pathogenic microorganisms
  5. reservoir of microorganisms with unique metabolic pathways and enzyms
17
Q

What is the conversion of atmospheric N2 into AMMONIA by some species of bacteria?

A

Nitrogen Fixation

18
Q

What type of bacteria is involved in nitrogen fixation?

A

free-living and symbiotic bacteria

19
Q

TYPE OF NITROGEN-FIXING BACTERIA

ability to fix nitrogen without association with other microorganisms

A

free-living

20
Q

TYPE OF NITROGEN-FIXING BACTERIA

capable of fixing nitrogen with the aid of a symbiont

A

symbiotic

21
Q

A symbiont can be (2)

A
  1. plant (legumes)
  2. organism (termites or protozoa)
22
Q

BACTERIA UNDER:

  1. Free-living (6)
  2. Symbiotic (3)
A

FL
1. Cyanobacteria
2. Anabaena
3. Nostoc
4. Azotobacter
5. Beijerinckia
6. Clostridium

SB
1. Rhizobium
2. Frankia
3. Azospirillum

23
Q

Where can SYMBIOTIC nitrogen fixing bacteria be found?

A

root nodules

24
Q

What color are root nodules and why?

A

red-brown due to LEGHEMOGLOBIN

25
Q

What is leghemoglobin?

A

oxygen-binding protein and iron-containing protein

26
Q

2 functions of leghemoglobin

A
  1. binds oxygen and supplies to the bacteria
  2. protects oxygen-sensitive nitrogenase
27
Q

Can plants use N to convert to Ammonium?

A

No

Thats why in symbiosissila w symbiotic bacteria

28
Q

TYPES OF GRAM NEGATIVE BACTERIA in

  1. Free-living (1)
  2. Symbiotic (1)
A
  1. Azotobacter
  2. Rhizobium
29
Q

2 Ways You Can Fix atmospheric nitrogen

A
  1. physically
  2. biologically
30
Q

Valid colony counts for:

  1. Bacteria
  2. Molds
A
  1. B: 25-250
  2. M: 10-150
31
Q

Can there be 3 consecutive dilutions with valid ranges for bacteria and molds?

A

No

MICROBIOLOGY (30 decks)

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