Q40 - Tracing Gene X Through Enucleate Sieve-Tube Elements

Theoretical 2 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Plants conduct sugars and other substances throughout their body by means of phloem. Phloem is a compound tissue, including different cell types (e.g. sieve-tubes elements (in angiosperms), companion cells and parenchymal cells.). In a study, DNA genomic samples prepared from sieve-tubes and companion cells of an angiosperm and investigated for DNA corresponding to X. Gene-specific primers were used to amplify gene X among whole genome of cells by PCR. Note: Each band represents a unique DNA molecule, asterisks denotes bands corresponding to functional genes.

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. Results of sieve-tube element genome analysis suggest that the plant is heterozygote in the gene X.

B. The results obtained for the sieve-tube cells can be explained by gene X being present both in the mitochondrial and chloroplast DNA.

C. Band A most likely corresponds to an organelle-related DNA sequences in the nuclear genome.

D. Band B most likely corresponds to a pseudogene in nuclear genome.

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Question reproduced from IBO 2018, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)