LEC 19

Question 1

Theory of Evolution

Answer 1

1. Scientific evidence indicates all living organisms on Earth are related

2.Believed that life descended from a single, simple, life-form that existed approximately 3 billion years ago

Question 2

___________ of life is thought to be a result of __________

Answer 2

1. Diversity
2. evolution

Question 3

Evolution three key elements

Answer 3

1. Descent over time
2. Modification
3. Unpredictable and natural

Question 4

Descent over time

Answer 4

slow change in populations over generations that makes them different from their ancestors

Question 5

Modification

Answer 5

change in phenotype of a species related to changes to the genes of an organism (mutation) or the reshuffling of genes through meiosis

Question 6

Unpredictable and natural

Answer 6

affected by chance, natural selection, historical events and changing environments

Question 7

Evidence for Evolution (3)

Answer 7

1. Fossils & fossil record
2. Comparative anatomy, embryology & biochemistry
3. Biogeography

Question 8

Theory of evolution was first proposed in the mid-1800’s by _________ ___________.
Based on _________ and evidence collected and never been any credible evidence to disprove the theory.

Answer 8

1. Charles
2. Darwin
3. observation

Question 9

Evidence: Fossils

Answer 9

Preserved remains of organisms

Question 10

Evidence: Fossils Process (2)

Answer 10

1. Occurs when remnants are covered sooner after death with layers of sediment & volcanic ash
2. Overtime they become mineralized and leave rock like impressions of hard tissues (bones, teeth etc.)

Question 11

Evidence: Fossils Details (5)

Answer 11

Have fossils for over 200,000 species

Many organisms we will never have information for because no hard tissues

Richest source of information but tends to be incomplete

Determine age by radiometric dating (either K+ or C-14)

Can observe or compare changes over time in an organism

Question 12

When different organisms share similar anatomical features it is usually because they came from ___________ ancestor.

Answer 12

common

Question 13

Evidence can compare: (3)

Answer 13

Anatomical structures
Development of embryos
Biochemical molecules

Question 14

anatomical structure types (3)

Answer 14

Homologous
Analogous
Vestigial

Question 15

Homologous structures

Answer 15

Body structures that share a common ancestor

Question 16

Homologous structures example

Question 17

Analogous structures

Answer 17

Structures that serve the same function but do not arise from a common ancestor

Question 18

Analogous structures example

Answer 18

bird and insect wing – both used for flight, however, no physiological similarities exist

Question 19

Vestigial structures

Answer 19

Structures that serve little or no function in an organism

Maybe homologous to body parts in other organisms

Question 20

Vestigial structures examples

Answer 20

Human tailbone (coccyx) is vestigial remains of a tail
Human appendix was once larger and had more absorption capability. Only has immune functions now.
Muscles for wiggling our ears
Wisdom teeth

Question 21

Evidence: Comparative Embryology

Answer 21

Comparing embryos of animals
Early embryonic development is similar among vertebrates

Question 22

All vertebrates develop: (3)

Answer 22

1. Notochord – becomes the core of the intervertebral discs
2. Somites – series of folds that become bone, muscle & skin
3. Gill or Pharyngeal arches – become either gills or part of face, middle ear & mouth

Question 23

Comparative Biochemistry

Answer 23

1. Examines similarities between proteins and genes of different species
2. When two species possess identical or nearly identical biochemical molecules, common ancestry may be indicated
3. The greater the difference, the further back the divergence is likely to have occurred

Question 24

Evidence: Biogeography

Answer 24

Study of the distribution of plants and animals around the world

Question 25

What contributes to a species ability to migrate?

Answer 25

1. Physical barriers may have prevented the spread of plants and animals from one area to another Oceans & mountains prevent movement of some species 2. Environmental conditions may make it impossible for a species to survive Too hot or cold for species to live

Question 26

Continental Drift

Answer 26

Pangea (tectonic plates all joined 200 million years ago) Started to drift and left related groups of organisms isolated from each other. These organisms evolved separately, but along almost parallel lines

Question 27

Evolution is the result of:

Answer 27

Mutations Natural selection Movement of organisms in/out of populations Chance

Question 28

Mutations

Answer 28

Random and rare changes in DNA of an organism May result from replication “errors” and/or epigenetics that get passed on to subsequent generations Give different form and function to the organism An accumulation of mutations may cause one species to diverge into two distinctly different species

Question 29

Theory of Evolution:

Answer 29

Life arose only once, probably in the primordial sea and all life as we know it descended from that early life form

Question 30

Natural Selection

Answer 30

Darwin proposed that individuals with certain traits are more “fit” for their local environment Since they are more “fit” to the area, they are therefore more likely to survive and reproduce (and pass on their “fit” traits to their offspring) Natural selection usually causes beneficial alleles to increase and harmful alleles to decrease in frequency in the gene pool of a population

Question 31

Genetic drift

Answer 31

Random changes in the allele frequency because of chance events More likely to occur in smaller populations (more vulnerable to change) than larger ones

Question 32

Genetic drift causes

Answer 32

Bottleneck effect Founder effect

Question 33

Bottleneck Effect

Answer 33

Major catastrophe occurs and wipes out most of a population Catastrophe has no regard for any previous measure of fitness Remaining individuals may not represent the original population nor the most “fit” genes

Question 34

Founder Effect

Answer 34

A few individuals leave the original group and begin a new population in a different location Environmental change that isolates a small population New gene pool may not be representative of the original population, nor the most “fit” genes

Question 35

Gene Flow

Answer 35

Redistribution of alleles Caused by immigration or emigration Results in mixing of gene pools that may not have otherwise mixed

Question 36

Antigenic Shift

Answer 36

Affects simpler populations (like viruses) Very rapid and dramatic change in a virus Caused when two or more viruses combine or exchange genetic material Forms a new virus with entirely different combination of genes that is potentially more infective than either of the two originals

Question 37

Extinction

Answer 37

Period when the life forms die out/disappears completely At least 5 mass extinctions over last 530 million years

Question 38

Most “recent” period of extinction

Answer 38

end of Cretaceous period Asteroid or comet collided with earth 65 million years ago Thought the collision caused significant global climate change

Question 39

Evolutionary Tree

Answer 39

Used to depict points of divergence between species Shows time, points of extinction and adaptive radiation

Question 40

Adaptive Radiation

Answer 40

New species develop in a relatively short period of time from a single ancestor Shown as numerous branches on an evolutionary tree