Microbial Ecology [2] Flashcards Preview

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Flashcards in Microbial Ecology [2] Deck (16):
1

Some lichen symbionts can survive independently on bare rocks in the absence of any external source of organic matter due to the ability of the phototrophic partner to fix CO2 from the air, and __________.
A production of acids by bacterial fermenters to release minerals from the rock.
B nitrogen fixation by the cyanobacterial partner
C chemolithotrophy by the bacterial partner.
D acquisition of water by the algal partner

B

2

Two organisms that both benefit from each other are in a symbiotic relationship called
A mutualism.
B ammensalism.
C commensalism.
D parasitism.

A

3


Bacterial symbionts of termite hindguts play a critical role in the termite's
A resistance to fungal infection.
B nitrogen metabolism.
C reproduction and nitrogen metabolism.
D reproduction.

B

4

Two main symbionts of termites are ________ and ________.
A fungi / protists
B bacteria / protists
C bacteria / fungi
D archaea / bacteria

B

5

Lichens are a mutualistic association of a fungus and either an alga or a cyanobacterium in which
A the fungus protects the photosynthetic partner from erosion.
B the fungus slowly engulfs the photosynthetic partner.
C the phototroph provides phosphorus to the fungus.
D the fungus helps collect sunlight for the photosynthetic partner.

A

6

What benefit does the fungal partner get from the lichen relationship?
A The alga anchors the fungus to the substrate.
B The alga produces lichen acids that help provide inorganic nutrients from the substrate.
C The alga provides organic compounds for food to the fungus.
D The alga facilitates water uptake.

C

7

A farmer finds that his soybean plants do not look healthy. They appear stunted and the leaves are a yellowish color, indicating possible lack of nitrogen. To have a more successful crop next year, he should consider__________.
A fertilizing his fields with iron.
B inoculating his fields with the appropriate cross-inoculation group of rhizobia
C fertilizing with ammonia fertilizer
D increasing irrigation of his fields.

B

8

Benefits of a nodulated plant include __________.
A increased oxygen produced through photosynthesis
B increased plant yield
C decreased nitrogen available to the plant
D decreased oxygen produced through photosynthesis

B

9

The role of the iron-containing leghemoglobin in the rhizobial root nodules of soybeans is to __________.
A carry iron to the rhizobial bacteria
B carry O2 from the leaves to the root nodule
C carry O2 from the root nodule to the leaves
D lower the amount of free O2 in the root nodule

D

10

Most nitrogen-fixing bacteria symbiotically associated with plants are called
A symbiodinia.
B rhizobia.
C bacteroids.
D mycorrhizae.

B

11

Plant root nodules are
A harmful to plants, because the bacteria outcompete the plants for nutrients.
B sites where nitrogen fixation occurs.
C formed from gall-rotting bacteria that decompose plant roots.
D structures created by fungi and are found in all agricultural crops.

B

12

The function of leghemoglobin in root nodules is to
A chelate iron.
B produce iron.
C bind oxygen.
D produce nitrogen.

C

13

How is a bacteroid distinguished from a bacterial cell?
A biochemical tests
B 16S rRNA gene sequencing
C cell morphology
D 16S rRNA gene sequencing, biochemical tests, and cell morphology

A

14

The specificity of certain rhizobia to infect only particular plants is in part due to the
A rhizobial lipids that act as signaling molecules.
B abundance of nutrients present in the soil.
C season (time of year).
D nifH genes they possess.

A

15

The mutualism of Azolla-Anabaena is useful for
tropical forest community succession.
aquaculturalists.
corn farmers.
rice farmers.

D

16

Place the steps of root nodule formation in the correct order.1. bacteroids 2. Nod factor secretion 3. invasion 4. recognition of partners 5. mature nodule
A 4, 3, 2, 1, 5
B 4, 2, 1, 3, 5
C 4, 1, 2, 3, 5
D 4, 2, 3, 1, 5

D