IMAT 2014 Q40 [Cell Identification]

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Two disease-­free cells, P and Q, were studied. Which option correctly identifies cell P as a typical plant cell and cell Q as a typical prokaryote?

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A. Row 1
B. Row 2
C. Row 5
D. Row 4
E. Row 3

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The answer to this question is choice A, or row 1.

Don’t be intimidated by this question, and instead approach it in a systematic way. Since this table offers a lot of information, it would be wise to eliminate choices first. One suggested efficient way to tackle this question is using the “Cell Q” column, or the cell that is supposedly the prokaryote:

  • Since one of the most important characteristic of prokaryotes is the lack of compartmentalization or the lack of organelles, you can eliminate the rows that include organelles. With that being said, you can eliminate rows 2, 3, and 5, since these are all structures that you will not be able to find in prokaryotes. You can consider row 1 since penicillin is an antibiotic designed to act against prokaryotes, and on the other hand, you can also consider row 4 since prokaryotes have cell walls as well (but do not be confused, the cell walls of prokaryotes differ from the cell walls of plant cells which are made of cellulose).
  • Now, you are left to decide which among in column “cell P”, whether row 1 or 4, is a correct association with plant cells. Let us take row 1, where it says “Gene for RuBisCo is present”. What is RuBisCo? It is an abbreviation for the enzyme called Ribulose-1,5-bisphosphate carboxylase-oxygenase, which is important in photosynthetic organisms where it acts in the first major step of converting carbon dioxide to other energy rich molecules. Thus, it would make sense that plants have the gene that encodes for this enzyme, which makes this as the correct answer.
  • Let’s not stop there, let us further strengthen our answer and prove why our remaining consideration, or row 4, is incorrect. Under the plant cell column, row 4 has put that “glycogen can be present”. This is false, since plant cells don’t produce glycogen. Instead, the analogous substance that plants have equivalent to animal cells having glycogen is starch. Plant cells produce starch and store them in granules.

Thus, the correct answer for this question is row 1, where the correct associations are made with plant cells and prokaryotes.

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