Unit 7: Natural Selection

Question 1

When does speciation occur?

Answer 1

When population are reproductively isolated from each other.

Question 2

What is the biological species concept?

Answer 2

Species are a group capable of interbreeding and exchanging genetic information to produce viable, fertile offspring.

Question 3

What is punctuated equilibrium?

Answer 3

Evolution occurs rapidly after a long period of stasis, periods of minimal to no change.

Question 4

What is gradualism?

Answer 4

Evolution occurs slowly over hundreds/thousands/millions of years.

Question 5

What is allopatric speciation?

Answer 5

Evolution of new species through the process of geographic isolation over a long period of time.

Question 6

What is sympatric speciation?

Answer 6

Evolution of a new species due to individuals being reproductively isolated from a surviving ancestral population.

Question 7

How do pre-zygotic mechanisms impact speciation?

Answer 7

They prevent sperm and egg from meeting

Question 8

How do post-zygotic mechanisms impact speciation?

Answer 8

They prevent a zygote from developing into a viable, fertile offspring.

Question 9

What is speciation?

Answer 9

The creation of new species.

Question 10

What does speciation result in?

Answer 10

Diversity of life forms.

Question 11

What are the effects of allopatric speciation?

Answer 11

No gene flow. Exposes populations to different selection pressures.

Question 12

What are the characteristics of sympatric speciation?

Answer 12

No geographic barrier. Can result from genetic mutations, polyploidy, habitat differentiation, and sexual selection.

Question 13

What is the stimulus for evolution?

Answer 13

Changing ecological conditions.

Question 14

What is adaptive radiation?

Answer 14

Evolution of new species that allows empty ecological roles or niches to be filled.

Question 15

What factors lead to extinction?

Answer 15

Catastrophic changes to an ecosystem; Human activity; Invasive species.

Question 16

How do environmental changes increase risk of extinction?

Answer 16

Mass destruction can result in habitat loss. Catastrophic events can wipe out many organisms.

Question 17

How do speciation and extinction rates impact species diversity?

Answer 17

High species biodiversity can result from high levels of speciation and low levels of extinction and vice versa.

Question 18

How does extinction create new niches?

Answer 18

When a species goes extinct, it leaves an open niche for another species to occupy.

Question 19

What is extinction?

Answer 19

Complete disappearance of a species

Question 20

What are the 5 pieces of evidence that support evolution?

Answer 20

geological- fossils; changes of environmental feature
geographical
physical- phenotypes
biochemical- chemical composition of living things
mathematic

Question 21

How are fossils dated?

Answer 21

dated through age of rock
decay of isotopes
geological data

Question 22

What demonstrates common ancestry for eukaryotes

Answer 22

membrane bound organelles
linear chromosomes
genes with introns

Question 23

Lamarck Evolution

Answer 23

evolution through inheritance of acquired traits

Question 24

Darwinian evolution

Answer 24

natural selection
–> mutation: longer neck giraffes survived and shorter neck died

Question 25

What allows evolution?

Answer 25

Mutation--> favorable traits accumulating/ struggle for survival, inherited trait

Question 26

what are the two types of dating for fossils?

Answer 26

relative: layer of soil fossil is found in absolute:radioactive isotopes (carbon 14 decrease after death)

Question 27

Define half-time

Answer 27

how much time it takes for half of carbon to disappear

Question 28

Define homologous structures

Answer 28

organisms with genetically similar structures= common ancestor common genes and similar anatomy but different environments and functions

Question 29

Divergent evolution

Answer 29

common genes but different environments and purpose

Question 30

define analogous structures

Answer 30

same function anatomically different; don't share a common ancestor

Question 31

define convergent evolution

Answer 31

don't share a common ancestry but developed similar functions

Question 32

define endemic species

Answer 32

found in one place

Question 33

embryology

Answer 33

vertebraes embryos look similar

Question 34

define stabilizing selection

Answer 34

average/immediate phenotype was selection; extremes selected against e.g. birthweight

Question 35

define disruptive selection

Answer 35

extreme phenotype was selected and average against

Question 36

define directional selection

Answer 36

one of the types of the extreme was selected

Question 37

define sexual selection

Answer 37

females choose male that is more superior

Question 38

name 10 sources of variation

Answer 38

mutations diploidy outrbreeding sexual reproduction gene flow chromosomal mutations nondisjunction DNA mutations transient polymorphism balanced polymorphism

Question 39

define diploidy

Answer 39

2 or more alleles

Question 40

define outbreeding

Answer 40

mating with unrelated partners

Question 41

gene flow

Answer 41

immigration/ emigration of individuals leaving or coming with diff. allele frequencies

Question 42

define transient polymorphism

Answer 42

a phenotype dominant, but a new phenotype becomes more dominant due to environmental changes

Question 43

define balanced polymorphism

Answer 43

maintenance of different phenotypes e.g. carrier of sickle cell

Question 44

conditions of hardy-weinberg equilibrium

Answer 44

1. large population 2. no mutation 3. no gene flow of allees 4. random mating 5. no natural selectio

Question 45

p=

Answer 45

frequency of dominant allele

Question 46

p^2

Answer 46

frequency of homozygous dominant genotype

Question 47

q=

Answer 47

frequency of recessive allel

Question 48

q^2

Answer 48

frequency of homozygous recessive genotype

Question 49

allopatric speciation

Answer 49

physical

Question 50

ecological speciation

Answer 50

live in same region, different habitat

Question 51

define temporal isolation

Answer 51

different mating seasons

Question 52

behavioral speciation

Answer 52

courtship dance

Question 53

mechanical isolation

Answer 53

mismatch genetalia

Question 54

gametic isoation

Answer 54

gamete may not fertilize egg

Question 55

origins of life explain

Answer 55

how organic compounds could come from inorganic precursors & then organic compounds undergoing further changes to form primitive cell-like structures

Question 56

What did the urey-miller experiment do?

Answer 56

tested the origins of life hypothesis; shown under lab conditions can stimulate the conditions of early Earth & organic molecules from inorganic substances

Question 57

RNA world hypothesis

Answer 57

a theory trying to figure out if DNA or RNA existed--> RNA came before DNA

Question 58

define a niche

Answer 58

organism's role in environment

Question 59

define deleterious traits

Answer 59

traits that reduce chance of survival