Lecture 3: The tree of life

Question 1

DEF: a family tree of organisms that describes the
genealogical relationships among species with a single ancestral species at its base.

Answer 1

The tree of life

Question 2

DEF: the actual genealogical relationships among all
organisms

Answer 2

Phylogeny

Question 3

Biologists study RNA and DNA from different
organisms:

• Compare sequences of the building blocks (_, _, _, _,)

Answer 3

A, T, C, G

Question 4

Fewer sequence variations between two species may
indicate a ______ ________

Answer 4

Closer relationship

Question 5

DEF: Is used to show the relationships between species

Answer 5

Phylogenetic tree

Question 6

• Branches that share a recent common ancestor
  represent species that are ____
• Branches that do not share recent common ancestors
  represent species that are more _____ related

Answer 6

Related, Distantly

Question 7

A phylogenetic tree is constructed using
sophisticated _____ _____

Answer 7

Computer programs

Question 8

Arrangement of _____ that is most consistent with the similarities and differences observed in the genetic data

Answer 8

Branches

Question 9

The universal tree or ____ __ ____ includes a diverse array of species

Answer 9

Tree of life

Question 10

Tree’s main ____ is the common ancestor of all living
species (aka Last Universal Common Ancestor or LUCA)

Answer 10

Node

Question 11

The 3 major groups of organisms of the tree of life:

Answer 11

The eukaryotes
- Eukarya

Two groups of prokaryotes
- Bacteria and Archaea

Question 12

A tree is a prediction, its validity is
based on current data. More robust
datasets could mean changes in the
tree’s shape or the position of its
branches. T or F

Answer 12

True

Question 13

DEF: the effort to name and classify organisms

Answer 13

Taxonomy

Question 14

DEF: a named group

Answer 14

Taxon

Question 15

DEF: Woese created this new taxonomic level

Answer 15

Domain

Question 16

Domain consists of 3 taxa:

Answer 16

• Bacteria
• Archaea
• Eukarya

Question 17

DEF: a major lineage within a domain

Answer 17

Phylum

Question 18

Who established the classification system still in use today (in 1735)?

Answer 18

Carolus Linnaeus

Question 19

Each organism is given a unique two-part
scientific name consisting of the _____ and the
_____

Answer 19

Gensus, species

Question 20

DEF: Made up of a closely related group of species

Answer 20

Genus

Question 21

DEF: Made up of individuals that regularly breed together or have characteristics that are distinct from those of other species

Answer 21

Species

Question 22

An organism’s genus and species designation is
called its _____ name or _____ name

Answer 22

Scientific, Latin

Question 23

An organism’s genus and species designation is
called its _____ name or _____ name

Answer 23

Scientific, Latin

Question 24

• Scientific names are always italicized.
  – Genus names are always capitalized,
  – Species names are not capitalized

T or F

Answer 24

True

Question 25

Humans can select certain individuals to produce
the most offspring leading to _____ selection

Answer 25

Artifical

Question 26

Adult male rams normally begin reproducing at six years of age. T or F

Answer 26

True

Question 27

____ mating success is dependent upon body size
and horn length.

Answer 27

Male

Question 28

Big horned sheep are hunted
for trophies, not for meat T or F

Answer 28

True

Question 29

Large males with long horns are not surviving long
enough to reproduce:
- The overall weight and horn length of four-year-old
rams has steadily ____.
- ____ selection from hunting has allowed the smaller
rams to breed

Answer 29

Decrease, artificial

Question 30

DEF: They allow researchers to test the effect of a single, well-defined factor on a particular phenomenon

Answer 30

Experiements

Question 31

Hypothesis testing is a 2-step process:
1. State the hypothesis as precisely as possible and list
the predictions it makes.
2. Design an observational or experimental study that is
capable of testing those predictions.

T or F

Answer 31

True

Question 32

The ______ hypothesis states:

• ____ always know how far they are from the nest
  – Because they track the number of steps taken
  – And they know length of their ____

Answer 32

Pedometer, Ants, Stride

Question 33

Wittlinger’s group manipulated the ants into three
groups after walking from the nest to a feeder:
1. ____ – legs were cut to form shorter-than-normal
legs
2. ____ – individuals were left alone with normal legs
3. _____ – bristles glued on legs to form longer-than-
normal legs

Answer 33

Stumps, Normal, Stilts

Question 34

Wittlinger’s groups also Measured the distance the ants travelled back to the nest via a different route T or F

Answer 34

True

Question 35

DEF: Specifies what we should
observe if the hypothesis being tested does not
hold

Answer 35

A null hypothesis

Question 36

Results:
– “Stumps” stopped short of the nest.
– “Normal” ants returned to the nest.
– “Stilts” walked beyond the nest

T or F

Answer 36

True

Question 37

Does the conclusion support the pedometer hypothesis:
– Desert ants use information on stride length and
number to calculate how far they are from the nest

Answer 37

Yes

Question 38

Well designed experiment needs what 3 things:

CET

Answer 38

1. Controlled groups
2. Experimental conditions controlled
3. Test was repeated

Question 39

We need control groups to:

Answer 39

To check for other factors that might influence the outcome

Question 40

We need experimental conditions controlled to:

Answer 40

To eliminate other variables

Question 41

We need to repeat tests to:

Answer 41

To reduce the effects of distortion due to small sample size