Chapter 13

Question 1

Microfossils

Answer 1

Fossilized forms of microscopic life

Question 2

Stromatolites

Answer 2

Mats of cyanobacterial cells that trap mineral deposits;

Oldest are 2.7 billion years old

Question 3

Biomarkers

Answer 3

Organic molecules of biological origin

Question 4

Prokaryotic diversity

Answer 4

oldest, structurally simplest forms of life;
Ubiquitous;
Bacteria and archaea (many are extremophiles)

Question 5

Prokaryotic features

Answer 5

Unicellularity;
Small;
Single circular double-stranded DNA chromosome found in the nucleoid;
No membrane-bounded organelles;
Cell division by binary fission;
Genetic recombination occurs through horizontal gene transfer;
Metabolic diversity;
Chemolithotrophic

Question 6

Metabolic diveristy

Answer 6

Two types of photosynthesis:

1. Oxygenic = Produces oxygen
2. Anoxygenic = Non-oxygen producing

Question 7

Plasma membrane (bacteria vs archaea)

Answer 7

Bacterial lipids are unbranched;

Archaeal lipids are branched

Question 8

Cell wall (bacteria vs archaea)

Answer 8

Bacteria have Peptidoglycan;

Archaea lack that

Question 9

DNA replication (bacteria vs archaea)

Answer 9

Archaeal DNA is more similar to that of eukaryotes

Question 10

Gene expression (bacteria vs archaea)

Answer 10

Archaeal transcription and translation are more similar to those of eukaryotes

Question 11

Early classification characteristics

Answer 11

1. Photosynthetic or non-photosynthetic
2. Motile or nonmotile
3. Unicellular or filamentous
4. Formation of spores or division by transverse binary fission
5. Importance as human pathogens or not

Question 12

Prokaryotic shapes

Answer 12

Bacillus= Rod-shaped
Coccus= Spherical
Spirillum= Helical-shaped

Question 13

Bacterial Cell Wall

Answer 13

Maintains shape and protects the cell wall from swelling and rupturing;
consists of peptidoglycan;
basis of gram stain

Question 14

Two main types of bacterial cell wall

Answer 14

1. Gram-positive

2. Gram-negative

Question 15

S-layer

Answer 15

A rigid paracrystalline layer found in some bacteria and archaea;
Aids in attachment

Question 16

Capsule

Answer 16

• A gelatinous layer found in some bacteria
• Aids in attachment
• Protects from the immune system

Question 17

Pili

Answer 17

• Short, hairlike structures
• Found in Gram-negative bacteria
• Aid in attachment and conjugation

Question 18

Flagella

Answer 18

• Long, helical structures
• Composed of the protein flagellin
• Involved in locomotion

Question 19

Nucleoid region

Answer 19

• Contains the single, circular chromosome

- May also contain plasmids

Question 20

Ribosomes

Answer 20

• Smaller than those of eukaryotes and differ in protein and RNA content
• Targeted by antibacterial antibiotics

Question 21

Internal membranes

Answer 21

• Invaginated cell membrane

- For respiration or photosynthesis

Question 22

Endospores

Answer 22

• Highly-resistant structures
• Released upon cell lysis
• Can germinate back to normal cell

Question 23

Prokaryotic gene transfer

Answer 23

• Conjugation = Cell-to-cell contact
• Transduction = By bacteriophages
• Transformation = From the environment

Question 24

Conjugation

Answer 24

• based on the presence of the F plasmid
• F+ cells contain the plasmid
• F- cells do not
• The F+ cell produce an F pilus that connects it to an F- cell

Question 25

R(resistance) Plasmids

Answer 25

-Encode antibiotic resistance genes

Question 26

Virulence plasmids

Answer 26

-Encode genes for pathogenic traits

Question 27

Mutualism

Answer 27

Both parties benefit

Question 28

Commensalism

Answer 28

One organism benefits and the other is unaffected

Question 29

Parasitism

Answer 29

One organism benefits and the other is harmed

Question 30

Decomposers

Answer 30

Release a dead organism’s atoms to the environment

Question 31

Photosynthesizers

Answer 31

Fix carbon into sugars

Question 32

Nitrogen

Answer 32

Fixers that reduce N2 to NH3 (ammonia

Question 33

Protists

Answer 33

``` Most diverse of the 4 eukaryotic kingdoms; Paraphyletic; Plasma membrane; Cysts; Flagella; Cilia; Pseudopodia ```

Question 34

Beneficial protists

Answer 34

- Protists are a food source - Protists provide food as a symbiont - Act as decomposers

Question 35

Fungi

Answer 35

Single-celled or multicellular; Sexual or asexual; Specialized to extract and absorb nutrients from surroundings

Question 36

Biology of fungi

Answer 36

Multicellular fungi consist of long, slender filaments called hyphae; Cytoplasm flows throughout hyphae; Mycelium – mass of connected hyphae; Fungal cell walls include chitin; Hyphae may have more than one nucleus; Heterokaryotic – nuclei from genetically distinct individuals; Homokaryotic – nuclei are genetically similar to one another; Fungi lack centrioles

Question 37

Fungi nutrition

Answer 37

Obtain food by secreting digestive enzymes into surroundings; Then absorb the organic molecules produced by this external digestion; Fungi can break down cellulose and lignin

Question 38

Fungi symbioses

Answer 38

- Obligate symbiosis – essential for fungus survival | - Facultative symbiosis – nonessential

Question 39

Fungi interactions

Answer 39

- Pathogen – pathogens harm host by causing disease - Parasites cause harm to host (do not cause disease) - Commensal relationships benefit one partner but does not harm the other - Mutualistic relationships benefit both partners

Question 40

Fungi disadvantages

Answer 40

Cause diseases in plants; Secrete substances making foods poisonous; Cause human and animal diseases