diversity of life

Question 1

do we have to study time frame for evolution???

Answer 1

IDK OMASFS

Question 2

what is the evolutionary origin of mitochondria & chloroplast?

Answer 2

engulfed prokaryotes that once lived as independent organisms

Question 3

what are the characteristics of the earliest forms of life?

Answer 3

they were prokaryotes. they were small, single-celled. has no nucleus and were anaerobic and autotrophs - they obtained carbon from organic molecules. likely bacterial

Question 4

what are the three domains of life?

Answer 4

eukarya, archaea, bacteria

Question 5

what to note about eukarya?

Answer 5

multi-cellular organisms, includes plants, fungi, and animals

Question 6

what to note about bacteria?

Answer 6

single-celled, prokaryotes, and contain peptidoglycan in cell walls

Question 7

what to note about archaea?

Answer 7

single-celled, prokaryotes, evolved from bacteria around 3500 million years ago

Question 8

what evidence is there that all life has descended from LUCA?

Answer 8

made of cells (surrounded by lipid membrane), contains DNA (heritable genetic code, all life uses same code), DNA to RNA (same proteins and enzymes to do this, ribosomes, polymerase, etc.), uses same energy currency (ATP) and the same proteins to generate ATP

Question 9

how did eukaryotic cells evolve chloroplasts?

Answer 9

endosymbiosis. from a photosynthetic bacterial symbiont (cyanobacteria). have circular dna genomes, genes for ribosomes, enzymes, divide independently, electron transport chains for photosynthesis

Question 10

how did archaeal cells evolve mitochondria?

Answer 10

endosymbiosis. from aerobic carbohydrate-eating bacterial symbiont, infoldings of membrane, and then over time symbiont loses genes required to live independently, some genes transferred to host cell’s dna in nucleus but some retained

Question 11

roles of retrovirus in evolution of mammals

Answer 11

involved in evolution of placenta, the organ that provides oxygen and nutrients to growing baby & removes waste products from baby’s blood during pregnancy. the retrovirus enveloped gene which evolved into syncytin which promotes cell fusion leading to the fusion of placenta.

Question 12

what are the mass extinction events?

Answer 12

ordovician-silurian, late devonian, permian, triassic-jurassic, cretaceous-tertiary

Question 13

what was the ordovician-silurian mass extinction?

Answer 13

occurred 440 million years ago. 85% of sea life was lost

Question 14

what was the late devonian mass extinction?

Answer 14

occurred 370 million years ago? 75% of animal species lost. vertebrates did not appear in fossil record for another 10 million years

Question 15

what was the permian mass extinction?

Answer 15

occurred 250 million years ago. 96% animal species lost, all current animals evolved form the 4%

Question 16

what was the triassic-jurassic mass extinction?

Answer 16

occurred 200 million years ago. 50% species lost. opened up habitats for dinosaurs to evolve

Question 17

what was the cretaceous-tertiary mass extinction?

Answer 17

occurred 65 million years ago. 75% animal/plant species lost, dinosaurs and other large animals and most flowering plants lost. opened up habitat for the diversification of mammals - “age of mammals”

Question 18

what are hominins?

Answer 18

modern humans and our bipedal ancestors

Question 19

what are the characteristics of early hominins?

Answer 19

large faces, protruding jaws, small skulls and brains

Question 20

did we evolve from apes?

Answer 20

no but they are said to be our closest relative

Question 21

where is evidence of early dispersal?

Answer 21

found in india. indications occupation 1.5 million years ago

Question 22

what are the challenges in recognizing modern humans as a distinct species?

Answer 22

genomic analysis shows that ancestors of modern humans interbred with both neanderthals and denisovans. if the biological species concept applied, the 3 groups are not separate species. the morphological evidence from fossils is incomplete and doesnt settle the matter

Question 23

what is the order of humans closest relatives?

Answer 23

chimpanzees and bonobos, followed by gorillas and then orangutans

Question 24

what are the costs of big brain?

Answer 24

energy, 2& of body weight, 20% of oxygen, makes childbirth more difficult

Question 25

what are the hypotheses for the evolution of big brain?

Answer 25

mating mind (intelligence and creativity attracts mate), cultural intelligence (intelligence used to hunt and build shelter), social intelligence (compete and cooperate with other members in face of challenge)

Question 26

what are some adaptations humans have developed?

Answer 26

bigger brain, lactose persistence, pale skin at high latitudes, immune receptors to parasites

Question 27

when did oxygen appear on earth?

Answer 27

2.5 billion years ago

Question 28

when did eukaryotes emerge?

Answer 28

1.5 billion years ago

Question 29

what are the evidence for endosymbiosis?

Answer 29

electron transport, genetic info/transcription/translation, reproductive mechanism, morphology of mitochondria/chloroplast