Question

what does a split in a phylogenetic tree signify?
a. the extinction of one of the species involved
b. the unrelatedness of the species involved
c. a common ancestor from which the species diverged
d. an environmental change affecting the species

what is a limitation of phylogenetic analyses?
a. complete data availability
b. missing genetic sequences leading to inaccuracies
c. no impact from missing data
d. clear ancestral reconstructions

clades in a phylogenetic tree represent:
a. groups of species sharing a common ancestor
b. unique species
c. ancestral species
d. dissimilar species

what type of data helps construct phylogenetic trees based on genetic relatedness?
a. paleontological
b. historical
c. molecular
d. morphological

Explanation:

• First question: In a phylogenetic tree, a split represents a common ancestor from which species diverged. Extinction (a) would not be shown as a split. Species in a tree are related (b is wrong). An environmental change (d) isn't what a split directly signifies.
• Second question: Missing genetic sequences (b) is a limitation. Complete data availability (a) is not a limitation. There is an impact from missing data (c is wrong). Clear ancestral reconstructions (d) is not a limitation.
• Third question: Clades are groups of species sharing a common ancestor (a). They are not unique species (b), not just ancestral species (c), and not dissimilar species (d).
• Fourth question: Molecular data (c) helps construct phylogenetic trees based on genetic relatedness. Paleontological (a) is fossil - based. Historical (b) is too broad. Morphological (d) is about physical form, not genetic relatedness as directly as molecular.

Answer:

c. A common ancestor from which the species diverged
b. Missing genetic sequences leading to inaccuracies
a. Groups of species sharing a common ancestor
c. Molecular