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CHAPTER 2
Structures and Functions of Life
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Question 1 - 3 refer to the following information.
Tuberculosis is caused by the mycobacterium, Mycobacterium tuberculosis,
which kills approximately half of all infected patients. For many years, M. tuberculosis
was susceptible to drug therapy; however, like many other disease-causing organisms,
new drug-resistant strains of tuberculosis have emerged. Many theories have been
postulated to explain the emergence of these resistant strains (also known as
"superbugs") but most healthcare professionals blame the over-prescription of
antibiotics as well as their misuse by patients.
Today, before a tuberculosis patient can be treated, it is first necessary to find
out which strain of bacterium is causing the disease and then to find a drug that will
kill that particular strain., a new technique has been discovered that aids this process.
Scientists can now insert luciferase, the enzyme that makes fireflies glow in the dark,
into tuberculosis cells taken from the patient, which makes the tuberculosis cells
glow in the dark (see Figure).
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With their new glow-in-the-dark organisms, scientists can then test different
drugs to see if they kill the bacteria (which stop glowing). This new test can be done
in days, which is faster than previous tuberculosis tests which required up to five weeks.
1. If a tuberculosis cell with luciferase is treated with a drug but keeps on glowing,
which of the following is most likely the case?
A. A higher dosage of the drug is needed.
B. The tuberculosis cell has been destroyed.
C. The cell is resistant to that particular.
D. Both A and C are correct.
2. What is likely to be the most important reason to save time on a tuberculosis
test?
A. The patient can begin effective drug therapy that much sooner.
B. The scientist can perform twice as many tests and thus have more time for
other experiments.
C. The enzyme luciferase lasts almost indefinitely.
D. Other types of bacteria have shown themselves less able to mutate.
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3. The following chart depicts the dose response curve of M. tuberculosis to an
antibiotic drug. If a scientist knows that an intensity score of 20 or less is
considered acceptable (the remaining bacteria can be eradicated by the host's
immune response), click on the dose of antibiotic that the scientist should
recommend for patients. (For this drill, mark the dose with an X.)
4. When a cell undergoes mitosis, it duplicates into two genetically exact replicas
of itself, so that the cells have exactly the same number of chromosomes as
did the original chromosomes. Meiosis, unlike mitosis, take place in two rounds.
scientists conduct an Experiment on three different cells, and track the
number of resulting cells and chromosomes after each cell undergoes either
meiosis or mitosis, according to the cell type. The results are shown below.
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Trial
Number of Initial
Chromosome
Number of final
Chromosomes in
Each Resulting
Cell
1
6
6
2
2
4
2
4
3
46
x
4
Number of Final
Cells
In trial 3, the cell undergoes ________________________(meiosis/mitosis) and
each resulting cell has ____ (23/46) chromosomes.
5. Most animals have internal or external skeletons for structure and support.
Which of the following parts provide a similar function in plant cell?
A. Cytoplasm
B. Chloroplasts
C. Cell Membranes
D. Cell walls
Question 6 - 7 refer to the following information.
The Cell and Heredity
Each cell in a living organism consists of a membrane surrounding a cytoplasm.
The cytoplasm is like jelly and has a nucleus in its center. Chromosomes are part of
the nucleus. They are important because they store DNA. DNA stores the genetic code
that is the basis of heredity.
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6. What determines what traits you inherit from your parents?
A. The cell
B. The atom
C. The nucleus
D. The neutron
E. DNA
7. What part of the chromosome carries the genetic code?
A. Membrane
B. Cytoplasm
C. Nucleus
D. Atom
E. DNA
Question 8 - 10 refer to the following passage.
Cells are the basic units of all living organisms. The following summarizes some
of the important differences between prokaryotic (bacteria) and eukaryotic (plant and
animal) cells. The major distinction is that eukaryotic cells contain membrane-bound
organelles such as mitochondria, chloroplasts, lysosomes, and the nucleus. Each of
these organelles carries out specialized functions.
Another difference between the various cell types is the presence or absence
of a cell wall. In bacteria, the cell wall provides structure to the cell, preventing if from
being crushed due to mechanical street or lysing due to osmotic stress. Osmotic stress
occurs because water tends to be drawn in to the cells since they typically contain
more ions than their surroundings. The rigid bacterial cell wall physically prevents this
increase in water from causing the cell to rupture.
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Animal cells face the same challenges but deal with them in different ways. The
cytoskeleton gives the cell structure and protects against mechanical stress. Animal
cells do not have a cell wall to protect against lysis so they must constantly pump
ions out of the cell. This decreases the tendency of water to enter the cell and protects
against rupture.
8. In eukaryotes, which organelle contains the vast majority of the genetic material?
A. Ribosome
B. Rough endoplasmic reticulum
C. Nucleolus
D. Nucleus
9. Antibiotics are drugs that are used to treat bacterial infections. They are effective
because that can specifically target bacteria without harming the human host.
Based on this information, which cellular structure would be a good target for
antibiotics.
A. Mitochondria
B. Cell membrane
C. Cell wall
D. Lysosome
10. Which of the following is a difference between eukaryotic and prokaryotic cell?
A. Prokaryotic DNA is store in the nucleus while eukaryotic DNA is not.
B. Eukaryotes are always motile while prokaryotes are seldom motile.
C. Prokaryotes actively pump ions across their membranes while eukaryotes
pump ions within the cell.
D. Eukaryotes use membranes to delineate specialized organelles while
prokaryotes do not.
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11. Most of the cells types in the body reproduce by mitosis except the gametes
which reproduce using meiosis. Which of the following is a difference between
mitosis and meiosis?
A. DNA must be replicated before meiosis but not mitosis.
B. In meiosis, there are two rounds of cell division but in mitosis there is only
one.
C. At the end of mitosis, the daughter cells have half the normal amount of
genomic DNA.
D. Meiosis uses prophase, metaphase, and telophase, but mitosis doesn’t.