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AP Biology TV: Assignment 1
The Cell Theory
Directions: only attempt the following questions AFTER viewing the video lectures posted on
AP Biology TV. Unlike most other HW assignments, each of your responses will be graded &
counted as a quiz.
1) The diagram below represents cork cells similar to those observed by Hooke under his
microscope. Do some research to identify where within the plant body one would expect to
find cork tissue. Based on your research, explain why Hook observed these cells to be
empty.
Location within plant body:
[1]
Empty Appearance:
[1]
2) Based on your response to question 1, what component of cork cells are most evident when
viewed under the microscope?
[1]
3) Explain why, although the microscope was invented in the 17 th century, the classic cell
theory was not proposed until the 19th century.
[2]
4) Which of the three tenets (“laws”) of the classic cell theory is true for all cells expect one?
Explain your response.
Tenet:
[1]
Explanation:
[1]
5) Identify the function of both the mitochondria & chloroplast.
Mitochondria:
[1]
Chloroplast:
[1]
6) Identify three characteristics of these organelles that seemingly violate the tenets of the
modern cell theory.
[3]
7) How might the evolutionary history of the mitochondria & chloroplast help to explain the
many “peculiar” characteristics they exhibit?
[2]
8) Explain the process of cell fractionation.
[2]
9) After a cell solution or homogenate is centrifuged, it is separated into two parts or
fractions. Identify & define these two fractions.
Fraction 1:
[1]
Definition:
[1]
Fraction 2:
[1]
Definition:
[1]
10) After spinning a cell homogenate, a researcher obtains a pellet at the bottom of the tube
containing the most-dense cellular components, mainly nuclei & mitochondria. To isolate
less dense components such as ribosomes, the researcher spins the remaining supernatant
at the same speed as the previous sample.
Identify the error in the procedure described above:
[1]
Explain why this error will prevent the researcher from obtaining a pellet containing ribosomes.
[2]
11) Under what circumstances is the process of density-gradient centrifugation applied?
[2]