theme 5c

Question 1

what are the 7 characteristics shared by all life forms?

Answer 1

all life...
①　displays order
②　harnesses and utilizes energy
③　reproduces
④　responds to stimuli
⑤　exhibits homeostasis
⑥　grows and develops
⑦　evolves

Question 2

approximately when did the earth form?

Answer 2

4.6 billion years ago

Question 3

what are the 3 major hypotheses on how the macromolecules essential for life were produced?

Answer 3

①　reducing atmosphere
②　deep-sea vents
③　extraterrestrial origins

Question 4

what is the reducing atmosphere hypothesis on the abiotic origin of macromolecules essential for life?

Answer 4

since the atmosphere was reducing, there was no ozone layer, and therefore no protection from UV rays from the sun. the UV rays were able to reach the lower atmosphere and, along with lightening, provided the energy needed for formation of biologically important molecules

Question 5

what is the deep-sea vent hypothesis on the abiotic origin of macromolecules essential for life?

Answer 5

the molecules could have originated on the ocean floor at hydrothermal vents, as they released superheated nutrient-rich water and reduced molecules

Question 6

what is the extraterrestrial origin hypothesis on the abiotic origin of macromolecules essential for life?

Answer 6

they came from space

Question 7

what does protobiont refer to?

Answer 7

a group of abiotically produced organic molecules surrounded by a membrane or membrane-like structure

Question 8

approximately when was the Archean era?

Answer 8

lasted from 4 billion to 2.5 billion years ago

Question 9

what happened in the Archean era?

Answer 9

➝　first origin of life
➝　evolution of prokaryotes (anaerobic and photosynthetic bacteria)
➝　oxygen starts to accumulate
➝　origin of aerobic respiration

Question 10

approximately when was the Proterozoic era?

Answer 10

lasted from 2.5 billion to 540 million years ago

Question 11

what happened in the Proterozoic era?

Answer 11

➝　high concentration of oxygen in atmosphere (Great Oxygenation Event)
➝　origin of eukaryotic cells
➝　evolution and diversification (protists, fungi, soft-bodied animals)

Question 12

what is endosymbiosis?

Answer 12

symbiosis between separate single-celled organisms; origin of eukaryotic organelles

Question 13

approximately when was the Paleozoic era?

Answer 13

lasted from 540 million to 250 million years ago

Question 14

what were 4 major events of the Paleozoic era?

Answer 14

➝　Cambrian explosion
➝　invasion of land
➝　appearance of gymnosperms
➝　major groups of tetrapods

Question 15

approximately when did the Cambrian explosion occur?

Answer 15

530 million years ago

Question 16

what happened during the Cambrian explosion?

Answer 16

rapid appearance of many groups of organisms
➝　features of many modern groups appear: heads, mouths, eyes, legs
➝　all major animal groups first appear

Question 17

what is a mass extinction?

Answer 17

event where the rate of extinction is much greater than that of speciation. more than 75% of known species go extinct in a geologically short interval. are periodic

Question 18

how do mass extinctions relate to evolution?

Answer 18

they are significant because they clear niches and make ecological opportunities available and leave “dead clades walking”–low diversity remnants of once diverse lineages