BMSC210 CH4.5

Question 1

What does the trunk or root of a phylogenetic tree represent?

Answer 1

Common ancient evolutionary ancestor

Question 2

What do the branches of a phylogenetic tree represent?

Answer 2

Evolutionary descendants

Question 3

What does LUCA stand for?

Answer 3

Last universal common ancestor

Question 4

What do the deeply branching bacteria represent?

Answer 4

Earth’s earliest life forms

Question 5

Why are the deeply branching bacteria called ‘deeply branching’?

Answer 5

They stem from the common root of life, deep and close to the LUCA root

Question 6

What do the earliest branches in phylogenetic trees represent?

Answer 6

Organisms most closely related to LUCA.

Question 7

What is the significance of deeply branching bacteria?

Answer 7

They may provide clues about ancient and now extinct forms of life.

Question 8

What are the living ancestors of deeply branching bacteria called?

Answer 8

Thermophiles or hyperthermophiles.

Question 9

Where do thermophiles or hyperthermophiles thrive?

Answer 9

At very high temperatures.

Question 10

What type of environmental conditions do the proposed first organisms thrive in?

Answer 10

Hot environmental conditions.

Question 11

What is unique about the class Aquificae and their adaptation to conditions?

Answer 11

Aquificae includes bacteria adapted to the harshest conditions on Earth.

Question 12

At what temperature do bacteria from the genus Aquifex thrive?

Answer 12

Temperature higher than 90 °C.

Question 13

Where can the species A. pyrophilus be found?

Answer 13

Near underwater hot springs.

Question 14

What are the extreme environments where Aquifex bacteria can be found?

Answer 14

Volcanoes and thermal ocean vents

Question 15

What is the temperature of water where Aquifex bacteria can thrive?

Answer 15

138 °C

Question 16

What type of substances do Aquifex bacteria use as nutrients?

Answer 16

Inorganic substances

Question 17

What was the condition of the earth when the ancient bacteria started evolving?

Answer 17

Hot and lacked an atmosphere

Question 18

What type of bacteria does the class Thermotogae represent?

Answer 18

Hyperthermophilic and some mesophilic anaerobic gram-negative bacteria

Question 19

What is the genus of bacteria that is able to use a variety of organic substrates and produce molecular hydrogen?

Answer 19

Thermotoga

Question 20

Where does T. maritima, a species of Thermotoga, live?

Answer 20

Near thermal ocean vents

Question 21

What is the temperature at which T. maritima thrives?

Answer 21

90 °C

Question 22

Where does T. subterranea, another species of Thermotoga, live?

Answer 22

In underground oil reservoirs

Question 23

Why is D. radiodurans considered a polyextremophile?

Answer 23

Because it can survive under many different kinds of extreme conditions

Question 24

What makes D. radiodurans unique?

Answer 24

Its ability to withstand doses of ionizing radiation that kill all other known bacteria

Question 25

What is the special ability of D. radiodurans attributed to?

Answer 25

Some unique mechanisms of DNA repair