chapter 20: the history of life

Question 1

How do biologists group organisms

Answer 1

they based them on shared/like characteristics

Question 2

what are the characteristics that biologists group organisms by

Answer 2

• fossil records
• morphology
• physiology
• behaviour
• embryological development
• DNA or RNA sequences

Question 3

what is systematics

Answer 3

reconstruction and study of evolutionary relationships

Question 4

what is an important thing to note about tree of life diagrams

Answer 4

they are subjective as they are based on the authors beliefs

Question 5

what is phylogeny

Answer 5

the hypothesis about relationships among taxonomic groups (is displayed through phylogenetic trees or cladograms)

Question 6

what are the types of phylogenetic trees

Answer 6

• rooted
• unrooted

Question 7

what is a rooted phylogenetic tree

Answer 7

uses single linage and represents a common ancestor at the base

Question 8

what is a unrooted phylogenetic tree

Answer 8

a diagram that is used to show the relationship between species but does not display a common ancestor

Question 9

what is the assumption that can be made when examining a rooted phylogenetic tree

Answer 9

in the common ancestor is not stated at the base then it is assumed to be Luka

Question 10

what are the are the parts of a phylogenetic tree

Answer 10

• taxon
• clade
• branch point (node)

Question 11

in regards to phylogenetic tree what is a taxon

Answer 11

the group of organisms

Question 12

in regards to phylogentic tree what is a claude

Answer 12

any branch or lineage that links taxons and branch points to the common ancestor

Question 13

in regards to phylogenetic trees what is a branch point / node

Answer 13

any point where a single lineage splits into two seperate clades (any branch point / node is where the most recent common ancestor (MRCA) is found)

Question 14

what are sister taxas

Answer 14

when two species are linked to the same closet branch points / nodes

Question 15

what is taxnomy

Answer 15

a science of classifying organisms into taxas

Question 16

what is the procedure of provided the name of a species through taxonomy

Answer 16

Genus (capitalozed) species name (lowercased)

Question 17

what determines a new species in the eyes of evolution

Answer 17

a singular shift in a nucleotide sequence

Question 18

How do systematists organize evolutionary relationship

Answer 18

they use diversity of evidence to determine between organisms in higher taxas

Question 19

what diversity evidence do systematists use to determine relationships between organisms

Answer 19

• Form and function
• behavioural
• genetic characters

Question 20

what are the two options for similarities with different organisms

Answer 20

• homologous character
• analogous characters

Question 21

what are homologous characters

Answer 21

structures or characteristics that are similiarly structured with in different organisms but potentially have different uses

Question 22

what are analogous characters

Answer 22

structure or characterisitics that are similar in apperance due to functions or ecological constraints

Question 23

what is convergence

Answer 23

when characterisitics are shaped by similar ecological or evolutionary constraints (selection pressures)

• this evolution is not a common ancestral trait

Question 24

What is evolutionary reversal

Answer 24

analogous characters that nay cause taxa to appear related when they are not related or distaintly related

• ancestral traits are sometimes lost in descendants in one group

Question 25

what are molecular comparisons

Answer 25

when nucleotide sequences DNA and RNA provide use information on the relationships between organisms

Question 26

what are the limitations to molecular comparisons

Answer 26

- when there are a smaller number of different nucleotides it can give the sense that it is a homologous characterisitc when they are not - certain mutations can cause sequencing to look unrelated when that is not the case

Question 27

Why do phylogenies matter

Answer 27

helps use understand the evolutionary relationships

Question 28

what is cladistics

Answer 28

the process of arganging taxas by homologous characters into clades (want to produce a cladogram where all clades are monophyletic)

Question 29

what are four things to remember about evolution

Answer 29

- mutations are random - it takes multiple mutations to lead to a new trait - a trait may be benifical, harmful, or neutral - evolution changes a population over time ( indivduals do not evole)

Question 30

what is the rule of parsimony

Answer 30

choose the simplest cladogram with the fewest steps or event

Question 31

what is horizontal gene transfer

Answer 31

the transfer of genetic material between unrelated species

Question 32

what are two major points to remember about HGT

Answer 32

- are more present in prokaryotes - mutations and HGT are the 2 main contributors to genetic variation `

Question 33

What are the methods of HGT

Answer 33

- Transformation - transduction - conjugation

Question 34

What is transformation in regards to HGT

Answer 34

when naked DNA is taken up by bacteria

Question 35

what is transduction in regards to HGT

Answer 35

when genes are transferred by virus (attaches to the cell and transfers information to it)

Question 36

What is conjugation in regards to HGT

Answer 36

when genes transferred between two virus cells

Question 37

what is meant by the endosymbiotic theory in eukaryotes

Answer 37

- mitochondria was engulfed by a different cell that was aerobic and was able to convert extra pyrvates in the cells into energy and the house cells would provide sugar from this mitochondrian process to occur (happened because of the access too oxygen within the host cell) - chloroplasts were also engulfed in this process