HISTORY OF LIFE ON EARTH

Question 1

WHEN DID THE FIRST CELLS APPEAR ON EARTH?

Answer 1

-3.8 bya

Question 2

WHAT WERE THE ORIGINAL SOURCES OF ENERGY?

Answer 2

-sunlight, radioactive decay, heat and electrical discharges

Question 3

WHAT HAPPENED DURING THE PREBIOTIC PERIOD?

Answer 3

-formation of basic organic compounds of living systems (saccharides, lipids, amino acids, nucleotides) via chemical reactions probably in reducing atmosphere (CO, CO2, CH4, NH3, H2S)

Question 4

WHAT WAS OPARIN AND HALDANES PRIMORDIAL SOUP?

Answer 4

-thought that with the mix of gases in the atmosphere and the energy from lightning strikes, amino acids could spontaneously form in the oceans

Question 5

WHAT WERE THE MILLER-UREY EXPERIMENTS?

Answer 5

-constant lightning shocks simulated using electric sparks, they were able to create organic compounds, including amino acids
-experiment seemed to prove that life on Earth could have spontaneously formed from nonorganic ingredients.

Question 6

WHAT IS THE ENDOSYMBIOTIC THEORY?

Answer 6

-how organelles arose in organisms, differing prokaryotic organisms from eukaryotic organisms

Question 7

WHAT IS THIS CELL AND ITS CHARACTERISTICS?

Answer 7

-prokaryotic
-lacks a nucleus and membrane enclosed organelles
-archaea and bacteria

Question 8

WHAT IS THIS CELL AND ITS CHARACTERISTICS?

Answer 8

-eukaryotic
-has a nucleus and membrane enclosed organelles
-unicellular = protists (2.1bya)
-multicellular = animals, fungi (565mya), plants (1.2bya)
-eukarya

Question 9

WHAT IS THE ANCESTOR OF MITOCHONDRIA?

Answer 9

-proteobacteria

Question 10

WHAT IS THE ANCESTOR OF CHLOROPLASTS?

Answer 10

-cyanobacteria

Question 11

WHICH DOMAIN IS THE CLOSEST TO EUKARYA?

Answer 11

-archaea are evolutionary closer

Question 12

WHAT WAS THE CAMBRIAN EXPLOSION?

Answer 12

-huge amount of new species became present (540mya)

Question 13

WHAT GROUP BELONGS TOT THE CHORDATES?

Answer 13

-vertebrates

Question 14

WHEN DID MAMMALS APPEAR?

Answer 14

-180mya (JURASSIC PERIOD)
-dramatic adaptations 65mya after extinction of dinosaurs

Question 15

WHICH PHYLA DO HUMANS BELONG TO?

Answer 15

-primates

Question 16

WHEN WAS THE EVOLUTION OF THE GENUS HOMO?

Answer 16

-2.5mya
-evolutional line probably led from some Australopithecus (A. afarensis?) through Homo habilis, Homo erectus and Homo heidelbergensis to Homo sapiens
-the closest relatives of Homo sapiens:
Neanderthals and Denisovans (pan troglodytes

Question 17

WHAT ARE THE THREE MODELS FOR THE ORIGINS OF HUMANS?

Answer 17

-“out of africa theory” (ancestor evolved in africa)
-“multi regional theory” (after exiting Africa, multiple homo species settled throughout the world. Modern humans then evolved from these ancestors across different locations worldwide = gave rise to modern dna)
-“the intermediate model” (modern humans may be the result of a migration out of Africa as well as some genetic contribution from non-African archaic groups

Question 18

WHAT IS THE THEORY OF THE MOLECULAR CLOCK?

Answer 18

-a hypothesis that came from an observation that for many proteins, the rate of amino acid substitutions appears to be constant over long periods of time.

Question 19

WHAT ARE PHOTOTROPHIC ORGANISMS?

Answer 19

-acquiring energy from sunlight (photosynthesis)

Question 20

WHAT ARE CHEMOTROPHIC ORGANISMS?

Answer 20

-acquiring energy from oxidation of chemicals
LITHOTROPHIC = oxidation of inorganic chemicals (prokaryotes only)
ORGANOTROPHIC = oxidation of organic chemicals

Question 21

WHERE DO AUTOTROPHIC ORGANISMS GET THEIR CARBON?

Answer 21

-inorganic compounds

Question 22

WHERE DO HETEROTROPHIC ORGANISMS GET THEIR CARBON?

Answer 22

-organic compounds

Question 23

WHAT ARE FACULTATIVE ANAEROBIC CELLS?

Answer 23

• primarily aerobic cells, but can switch to anaerobic metabolism = yeast, muscle cells – can work during oxygen depts

Question 24

HOW DID THE NUCLEUS AND ER EVOLVE IN EUKARYOTES?

Answer 24

-formation of nucleus and endoplasmic reticulum occurred via the invagination of the cytoplasmic membrane

Question 25

DO PROKARYOTES OR EUKARYOTES HAVE A HIGHER VARIABILITY IN BIOCHEMICAL CAPABILITIES?

Answer 25

-prokaryotes

Question 26

IS GENOME SIZE DEPENDENT ON COMPLEXITY?

Answer 26

-size of genome is significantly different in various evolutional lines and does not depend on the organism’s evolutional development.

–> e.g. human can have a smaller genome than a unicellular eukaryote or amphibians

ALSO; the number of genes in a genome does not correlate with the size of the genome (due to introns)