PIMSO 2022 - Science - Grade 9 - National Round Question 6

Question 6

The following graph shows the phylogenetic tree of representative genomic sequences of SARS-CoV-2 variants worldwide. Which of the following statements is not true regarding the variants, as demonstrated by the tree? Reference: Hadfield J, Megill C, Bell SM, Huddleston J, Potter B, Callender C, Sagulenko P, Bedford T, Neher RA. Nextstrain: real-time tracking of pathogen evolution. Bioinformatics. 2018 Dec 1;34(23):4121-3.

Question illustration

Historical scope: use the ancestry shown in this source snapshot. Its sampling is not a complete global prevalence survey.

The Omicron variant evolved from the Delta variant.
The Omicron variant has currently two subvariants.
The Omicron variant is currently the prevalent strain worldwide.
The Delta variant was the most prevalent strain during 2021.
The Delta variant still exists among the population.