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MCAS Bacteria Viruses and Fungi

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Spring 2017 MCAS. Show all your work (diagrams, tables, or computations) in your Student Answer Booklet. If you do the work in your head, explain in writing how you did the work. Write your answer in the space provided in your Student Answer Booklet.
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A population of S. epidermidis decreases the population sizes of other types of bacteria on the skin.

a. Describe one way decreasing the population sizes of other bacteria on the skin helps the S. epidermidis population.

b. Identify the process that S. epidermidis cells use to reproduce.

c. Describe two similarities between the process that skin cells use for cell division and the process that you identified in part (b).

When S. epidermidis moves from the skin into the body, it behaves like an invasive species entering a new ecosystem.

d. Will the S. epidermidis population size decrease, increase, or stay the same after the bacteria enter the body? Using your knowledge of invasive species, explain your answer

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Spring 2017

Topics: Biochemistry, Protista, Classification

Diatoms are marine organisms with unique cell walls that contain the element silicon. Which of the following are two common elements found in the cells of diatoms?

A. aluminum and magnesium
B. helium and hydrogen
C. mercury and neon
D. nitrogen and phosphorus

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The human body contains diverse types of bacteria. Scientists estimate that the average healthy adult human body is home to at least 10,000 species of bacteria. In fact, there are about 10 times more bacterial cells than human cells in the human body.

Many bacterial populations are important to the normal functioning of human body systems. For example, some bacteria in the digestive system produce substances the human body cannot produce. These substances help the body break down and absorb nutrients. However, bacteria that help the human body in one location can cause serious illness if introduced to a different part of the body.

Bacteria MCAS question

8. This bacteria, S. epidermidis, can sometimes infect wounds. The symptoms of the infection include swelling, pain, pus, skin that is warm to the touch, and redness at the
infection site. Based on the symptoms, which of these human body systems work together to restore homeostasis?

A. circulatory system and immune system
B. immune system and reproductive system
C. skeletal system and respiratory system
D. respiratory system and nervous system

9. Which of the following is a characteristic that distinguishes viruses from B. thetaiotaomicron and S. epidermidis?

A. Viruses lack mitochondria.
B. Viruses lack genetic material.
C. Viruses are unable to accumulate mutations.
D. Viruses are unable to reproduce outside of host cells.

10. Which of the following best explains how antibiotic resistance spreads through
some populations of S. epidermidis?

A. All S. epidermidis cells exposed to antibiotics respond by developing mutations.

B. Some S. epidermidis cells exposed to antibiotics survive and pass their genes on to their offspring.

C. Exposure to antibiotics causes S. epidermidis cells to learn simple behaviors that help the cells survive.

D. Exposure to antibiotics causes an increase in the respiration rate of S.epidermidis cells living on the skin.

11. Which of the following describes one way B.thetaiotaomicron helps in digestion?

A. It breaks down lipids into fatty acids.
B. It breaks down proteins into amino acids.
C. It breaks down polysaccharides into simpler sugars.
D. It breaks down nucleic acids into nitrogenous bases.

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Mini-essay question:

A population of S. epidermidis decreases the population sizes of other types of bacteria on the skin.

a. Describe one way decreasing the population sizes of other bacteria on the skin helps the S. epidermidis population.

b. Identify the process that S. epidermidis cells use to reproduce.

c. Describe two similarities between the process that skin cells use for cell division and the process that you identified in part (b).

When S. epidermidis moves from the skin into the body, it behaves like an invasive species entering a new ecosystem.

d. Will the S. epidermidis population size decrease, increase, or stay the same after the bacteria enter the body? Using your knowledge of invasive species, explain your answer.

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Feb 2016 MCAS.  Medicines called antifungals are used to treat infections caused by fungi. One way antifungals work is by targeting cell parts that are present in fungal cells but not in human cells.

c. Identify one cell part other than a ribosome or a plasma membrane that human cells and fungal cells have in common.

d. Describe what would happen to a human cell if the cell part you identified in part (c) were affected by an antifungal. Explain your answer based on the function of the cell part.

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