Key Knowledge 12

Question 1

homologous structures 

Answer 1

features present in two or more species that may look and function very differently in each species, but are derived from a common ancestor

Question 2

divergent evolution 

Answer 2

the process in which a common ancestor evolves into two or more descendant species

Question 3

analogous structures 

Answer 3

features present in two or more species that fulfil the same function but do not originate from a common ancestor

Question 4

convergent evolution 

Answer 4

the process in which distantly related species evolve similar traits over time due to the action of similar selection pressure

Question 5

vestigial structures 

Answer 5

features that have lost all or most of their usefulness as a result

Question 6

molecular homology 

Answer 6

the study of the similarities in the nucleotide sequences of DNA or amino acid sequences in proteins between organisms to establish relatedness

Question 7

conserved genes 

Answer 7

genes that have remained largely unchanged throughout evolution, and are found across the genome’s of many different species

Question 8

cytochrome c 

Answer 8

an enzyme found in mitochondria that carries electrons in aerobic and anaerobic respiration reactions

Question 9

mitochondrial DNA (mtDNA)

Answer 9

 circular DNA found in mitochondria

Question 10

phylogenetics 

Answer 10

the study of the relatedness between organisms

Question 11

phylogenetic tree 

Answer 11

a diagram used to show the relatedness between organisms

Question 12

evolutionary relationship

Answer 12

the relatedness of organisms based on shared ancestry

Question 13

lineage 

Answer 13

a direct sequence of species that evolved from a common ancestor

Question 14

root 

Answer 14

represents the most recent common ancestor for all members of a phylogenetic tree

Question 15

branch 

Answer 15

a line on a phylogenetic tree that represents an evolutionary path

Question 16

node 

Answer 16

the splitting point between two branches on a phylogenetic tree, representing a speciation event

Question 17

leaf 

Answer 17

the end of a branch that shows the current (or final) form of a species

Question 18

A phylogenetic tree of these animals can be constructed using the following steps:

Answer 18

1. We first figure out the trait that is shared by the largest number of animals.
2. Then we look for the trait shared by the second-largest number of animals, which in this case is the fur.
3. Finally, it can be noticed that both marsupials and placental mammals have fur, so the marsupials and placental mammals lineages are branching directly from the trait fur.

Question 19

adaptive radiation 

Answer 19

the rapid divergent evolution of a species, thereby producing a wide array of species/forms