QUESTION 7 Which statement most accurately describes the evolutionary relationsh

Question

QUESTION 7

Which statement most accurately describes the evolutionary relationships among the three domains?

Bacteria and Archaea diverged from a common ancestor more recently than they diverged from their common ancestor with Eukarya

Bacteria and Eukarya diverged from a common ancestor more recently than they diverged from their common ancestor with Archaea

Eukarya and Archaea diverged from a common ancestor more recently than they diverged from their common ancestor with Bacteria

All three domains diverged from a common ancestor at the same time.

10 points   

QUESTION 8

Bird influenza is an emerging disease. If you were given the task of using Koch's postulates of finding the pathogen causing bird flu, what sequence of procedures should you use?

(1) Inoculate a healthy bird with the suspected pathogen to see whether it becomes sick, (2) compare symptoms of that bird with those of a bird known to have the disease, (3) isolate the pathogen from both birds in pure culture and stain them to see whether they are both Gram-positive, and (4) make a vaccine from the pure culture of one bird and inject it into another to see if it recovers.

1) Take blood samples from a sick bird, (2) isolate the pathogen in pure culture, (3) treat the bird for the disease and when it recovers take a second blood sample, and (4) test the blood to check whether it no longer contains the pathogen.

1) Inject a bird with the suspected pathogen, (2) inject another bird with a control that doesn't contain the suspected pathogen, (3) repeat with more birds, and (4) plate out samples of blood from both kinds of birds to see if you can isolate the pathogen in pure culture.

(1) Check whether the suspected pathogen is present in sick birds, then (2) isolate the pathogen from an infected bird and grow it in pure culture, (3) inoculate cells from pure culture into a healthy bird to see whether it causes the disease, and (4) attempt to isolate the suspected pathogen from the inoculated bird.

10 points   

QUESTION 9

The evolution of organisms that use oxygen in their respiration was possible only because of the action of a group of bacteria that produced oxygen and changed the Earth's atmosphere from an anoxic one to one rich in oxygen. That group of bacteria was:

cyanobacteria

spirochaetes

proteobacteria

Staphylococcus

10 points   

QUESTION 10

Microcystis aeruginosa is a species of cyanobacteria. What CANNOT be true of this species?

It synthesizes organic molecules.

It is an obligate anaerobe

Its cells contain an extensive thylakoid

It uses ammonia to produce proteins.

Bacteria and Archaea diverged from a common ancestor more recently than they diverged from their common ancestor with Eukarya

Bacteria and Eukarya diverged from a common ancestor more recently than they diverged from their common ancestor with Archaea

Eukarya and Archaea diverged from a common ancestor more recently than they diverged from their common ancestor with Bacteria

All three domains diverged from a common ancestor at the same time.

Explanation / Answer

7. Third option is the correct answer.

The difference in 16srRNA genes is the basis for classification of three domains of life.

8. Fourth option is the correct answer

The four criteria of Koch's postulate are followed in correct sequence in last option given in the question.

9. Cyanobacteria

Cyanobacteria are considered to be the bacteria who played a big role in evolution due to oxygen producing capacity.

10. It is an obligate anaerobe

Cyanobacteria produce gaseous oxygen as byproduct of photosynthesis and therefore a species of cyanobacteria cannot be obligate anaerobes.

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