Microbiology Answers

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)

What is the principle of the dextrose broth test (a biochemical test)? is it to test the ability to utilize dextrose as carbon source? but can I have an in-depth elaboration/explanation about this test?

1.     Define demography. (1 mark)

Demography is statistical study of population changes over time: birth rates, death rates, migration rates etc. 

is this an okay answer? please let me know. thank you.

1.     Explain chemical warfare and its role in predator-prey interactions. Provide an example of the use of chemicals or toxins. (2 marks)

Chemical warfare is a toxic poison that is used to kill or injurer an enemy. An example that used chemical warfare is that a monarch butterfly lay its eggs on the milkweed plant. When the eggs hatch, they consume the toxic poison. The caterpillars store the poison in their tissues as a defense against their own predators.  

2.     Explain what having a RLF of 2.1 means. What happens to a population if it is less than the RLF? (2 marks)

Replacement level fertility (RLF) is an average number at which a population replaces itself from one generation to the next without migration. If a population is less than RLF then this raises concerns for the population and as a result, incentives are offered to couples so they can have more children. 

are my answers correct?

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 two populations share the same geographic area. Ecological isolation can reduce gene flow, and mutations can lead to genetic isolation. 

is this right?