Why is it very challenging to find and identify signs of early cells?
What will be an ideal response?
Cells are microscopic and most have no hard parts to fossilize. In addition, few ancient rocks that might hold early fossils still exist. Tectonic plate movements have destroyed nearly all rocks older than about 4 billion years, and slightly younger rocks have often been subject to heating and other processes that destroy traces of biological material. To add to the difficulty, structures formed by nonbiological processes sometimes resemble fossils which makes scientists question the identity of fossils that are found.
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Which is an immediate effect of blocking the activity of mitochondrial ATP synthase?
A. The pH in the space between the mitochondrial membranes would increase. B. The concentration of NADH would increase. C. ATP synthesis would increase. D. The pH in the space between the mitochondrial membranes would decrease. E. Oxygen consumption would decrease.
Excitatory postsynaptic potentials are generally caused by _______channels opening, while inhibitory postsynaptic potentials may be caused by _______ channels opening.
a. Na+; Cl– b. K+; Cl– c. Ca2+; K+ d. Cl–; K+
A sterile hybrid plant can form a fertile new species if its chromosomes are doubled. This is referred
to as
a. allopatric speciation b. cladogenesis c. a hybrid zone d. anagenesis e. sympatric speciation
Whales appear to be most closely related to cows based on the presence of specifically shaped in the feet of ancient whale ancestors.
A) founder effect
B) Homo Habilis
C) Latin binomial
D) Australopithecus Africanus
E) convergent evolution
F) Ardipithecus ramidus
G) Neanderthals
H) chimpanzees
I) Homo erectus
J) astragalus