Chapter 19: Life's Origin + Early Evolution
Eukaryotes have mitochondria. What does the endosymbiont hypothesis say about the origins of mitochondria?
A prokaryote capable of cellular respiration was engulfed by an early eukaryote and became an endosymbiont.
is a field of study concerned with the origins, evolution, and persistence of life on Earth as it relates to life in the universe.
Astrobiology
Which of the following statements correctly describes what conditions on Earth were like when it first formed?
Bare rock, molten lava, with little water and little to no oxygen in the atmosphere
According to the ........ ............. .... the universe formed about 13.7 billion years ago in an instant, with all matter and energy exploding outward. Assessment question
Big Bang Theory
The endosymbiont hypothesis states that early eukaryotic cells engulfed prokaryotes capable of
Cellular Respiration
Which of the following is the only bacteria to photosynthesize by a pathway that produces oxygen as a by-product?
Cyanobacteria
Which of the following is an underwater opening from which mineral-rich water heated by geothermal energy streams out?
Hydrothermal vent
Proteins that speed metabolic reactions might have first formed when reactants began interacting inside tiny holes in rocks near deep-sea
Hydrothermal vents
The lack of _____ in Earth's early atmosphere favored the formation and accumulation of organic molecules.
O2
Four of the following were likely in Earth's earliest atmosphere. Which one was not?
Oxygen
Life probably would never have emerged on Earth if the ancient atmosphere had been the same as the present one in regard to the content of ____.
Oxygen
Oxygen in the upper atmosphere formed
Ozone gas
modern eukaryotes have mitochondria, and later some eukaryotes engulfed prokaryotes capable of
Photosynthesis
Which of the following factors is most responsible for increased levels of oxygen in Earth's early atmosphere?
Photosynthetic cyanobacteria
They contain DNA.
Protocells
The hypothesis that RNA served as the genetic information of early life is called _________________.
RNA world hypothesis
Which of the following is NOT a shared characteristic of both protocells and prokaryotes?
The presence of a membrane bound-nucleus.
Earth's surface and preventing DNA damage from excessive
UV Light
The ozone layer is valuable because it blocks
UV radiation.
The formation of amino acids under abiotic conditions was important because they serve as ____.
a supply of structural units for proteins
Our planet, Earth, is the third planet from the sun. Earth formed.............the sun was formed.
after
The first cells were ____.
anaerobic
The hypothesis that mitochondria and chloroplasts evolved from bacteria is called
endosymbiont hypothesis.
Early anaerobe life-forms were most likely _____.
heterotrophs
The by-product of the metabolism of cyanobacteria that had the most effect on the further evolution of life is ____.
oxygen gas
A membranous sac that contains interacting organic molecules, hypothesized to have formed prior to the earliest life-forms:
protocell.
The oldest proposed cell microfossils come from structures called _____.
stromatolites
The folding inward of the plasma membrane of an ancestral prokaryote likely evolved into ____.
the nucleus
The accumulation of free oxygen in the atmosphere ____.
was a result of the accumulation of a by-product of a type of photosynthesis
The first cells likely survived in Earth's early atmosphere because they _____.
were anaerobic
