Biology Questions and Answers
molecules from the environment setting
out an evolutionary selection.
- What is the evolutionary
origin of the internal
membranous organelles of the
cell?
It is accepted that the internal
membranous oeukaryotic, like the Golgi arganelles of thepparatus a (^) nd
the endoplasmic reticulum, appeared
from invamembrane of primitive cells.ginations of the external
- How have prokaryotic cells
given origin to aerobic
eukaryotic cells and to
photosynthetic aerobic
eukaryotic cells?
According to the most accepted
hypothesis aerobic eukaryotic cellsemerged from the association of aerobic (^)
prokaryotes engulfed by primitive
anaerobic eukaryhave been the origin of mitochonotic cells. This wdriaould
that thus would have primitively been
aerobic banaerobes. This hypothesis isacteria engulfed by eukaryotic called the (^)
endosymbioticof mitochondria. hypothesis on the origin
Chloroplasts would also havby endosymbiosis from the entry ofe appeared
photosynthetic prokaryotes into aerobic
eukaryotes, bmutualist ecological interaction.oth establishing a
- What evidence
strengthens the hypothesis
that chloroplasts could have
been photosynthetic
prokaryotes and mitochondria
could have been aerobic
prokaryotes?
The fact that chloroplasts are the
organelles responsiblphotosynthesis in plants leads to the for (^) e
supposition that before symbiosis they
were autotropreason that mitochohic prokaryndria are the centerotes. For the (^)
of the aerobic cellular respiration, the
powerhouse of the eukaryoticsupposed that they were once aerobic cell, it is
prokaryotes.
The endosymbithe emergence of aerobic anotic hypothesis to explaind
autotrophic estrengthened further by the followiukaryotic beings is (^) ng
evidence: chloroplasts as well as
mitochosimilar to bacterial DNA; cndria have their own DNA,hloroplasts (^)
and mitochoby binary division, ndria reproduce asexlike bacteria do; bothually (^)
organelles have ribosomes and
synthesize proteins.
- How did the first
fermenting autotrophs
appeared? What about the
first aerobic beings?
The heterotrophic hypothesis asserts
that thfermenting e first living heterotrophs. Fermbeings were theentation (^)
released carbon dioxide (CO 2 ) and then
the atmospthis gas. By mutation anhere became ed naturalnriched by
selection organisms capable of using
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