The appearance of Pax-6 in all animals with eyes can be explained in multiple ways. Based on the information above, which explanation is most likely?
A) Pax-6 in all of these animals is not homologous; it arose independently in many different animal phyla due to intense selective pressure favoring vision.
B) The Pax-6 gene is really not one gene. It is many different genes that, over evolutionary time and due to convergence, have come to have a similar nucleotide sequence and function.
C) The Pax-6 gene was an innovation of an ancestral animal of the early Cambrian period. Animals with eyes or eyespots are descendants of this ancestor.
D) The need for eyes has resulted in the separate evolution of Pax-6 genes.
C
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Pili may do all of the following EXCEPT
a. help cells attach to surfaces. b. function in reproduction. c. extend from the cell surface. d. be transferred between cells. e. function in cell locomotion
Mendel found that pea plants expressing a recessive
trait a. were pure-breeding. b. appeared only in the first generation of a cross between two pure-breeding plants expressing contrasting forms of a trait. c. disappeared after the second generation. d. could be produced only if one of the parents expressed the recessive trait. e. were none of these.
Infectious proteins that are heat resistant and that cannot be destroyed by ultraviolet light or most chemicals are known as ________
Fill in the blank(s) with correct word
Cells have specialized structures to help in carrying out its functions. Which of the following is most likely to be found in large numbers inside a cell that continuously makes proteins?
A) chloroplasts B) ribosomes C) chromosomes D) channel proteins