Microbiology Answers

What makes the acid-fast bacteria more pathogenic than other bacteria?

What will be the microscopic appearance of Mycobacterium after gram staining? Explain why.

1) When is rectal swab specimen acceptable for culture of enteropathogens?  

2) What is the most accurate method for species identification of Salmonella and Shigella?  

What are prokaryotes?

a.     You are having a conversation with Cindy, the magic turtle. Cindy is very curious about the formation of species. She tells you excitedly how one species of turtle inhabited the same geographical area, but ended up forming two different species over time. She admits she is a bit surprised by this; she thought that populations needed to be geographically separated from each other in order to form two different species. Explain to Cindy how speciation can occur without geographical separation. Name the type of pathway to speciation that occurred in this case. (3 marks)

Speciation can occur without geographical separation through sympatric speciation. Sympatric speciation is best defined as when organisms encounter chromosomal errors during meiosis such as polyploidy. Polyploidy is when species have an extra chromosome than the previous species. This can also lead to genetic modification where species are in a competition with one another for survival.

correct now?

1.     Define demography. (1 mark)

Demography is a statistical study of population that keeps on changing over time through, birth rates, death, and migration rates.   

is my definition correct?

a)     Assume the population of Bacteria B completely dies off. Bacteria A are now transferred to an open environment where they have lots of room for growth and a continual supply of food. Over the course of three days, the population of bacteria steadily increases as follows:

Day 1: 1500 bacteria

Day 2: 3000 bacteria

Day 3: 7000 bacteria

Day 4: 13,000 bacteria

Is this population of bacteria r-selected or k-selected? Explain how you arrived at your answer. Hint: Review your definitions of “r” and “k.” (2 marks)

This bacteria is k selected, because k-selected species mature slowly, they have a longer life span and they provide more parental care so that when their offspring matures it can survive in any environment.  is my answer right?

1.     Bacteria A and Bacteria B are considered hardy bacteria and can survive in extreme environments when grown individually. However, when they are grown together in a closed environment (on an agar plate), Bacteria A thrives, while Bacteria B eventually dies off. 

a)     Calculate the density per cubic centimetre of Bacteria A on the agar plate if there are 1500 bacteria on a 100cm³ plate. (1 mark)

Dp=N/A

1500/1000^3

=1.5 x10^-6 

this right?

1.     Bacteria A and Bacteria B are considered hardy bacteria and can survive in extreme environments when grown individually. However, when they are grown together in a closed environment (on an agar plate), Bacteria A thrives, while Bacteria B eventually dies off.

a)     Using your knowledge of competitive exclusion, explain what has happened. (2 marks)

Bacteria A and B are competition for the same limited resource on the agar plate, therefore both can’t live in the same place. So, one bacteria attacks the other until it dies.

 is this answer correct?

1. c)  Assume the population of Bacteria B completely dies off. Bacteria A are now transferred to an open environment where they have lots of room for growth and a continual supply of food. Over the course of three days, the population of bacteria steadily increases as follows:

Day 1: 1500 bacteria

Day 2: 3000 bacteria

Day 3: 7000 bacteria

Day 4: 13,000 bacteria

Is this population of bacteria r-selected or k-selected? Explain how you arrived at your answer. Hint: Review your definitions of “r” and “k.” (2 marks)