BIO CHAP 20 Flashcards
In the Drosophila embryo, gap genes govern the partitioning of the anterior-posterior gradient into segments.
TRUE
Which one of the following statements does not support the argument against multiple independent origins of eyes?
Pax6 protein is so central to eye development that after transferring the mouse Pax6 to the fruit fly, the fly produced eyes similar to that of a mouse.
Pax6 is a transcription factor that can act as a repressor for some of its target genes or as an activator for others.
TRUE
Which of the following statements about maternal-effect genes is not correct?
The caudal and hunchback mRNAs are transcribed in the egg and then transported back to regulate the mother’s genome.
Which one of the following statements points out a significant limitation to the analogy between genetic programs and computer programs?
Genetic programs evolve, whereas computer programs do not.
An example of gene regulation at the level of translation is the ability of the Bicoid protein to repress translation of caudal mRNA and for Nanos protein to repress translation of hunchback mRNA.
TRUE
The fertilized egg is totipotent, whereas the cells from the inner cell mass, called embryonic stem cells, are pluripotent. Only the embryonic stem cells can give rise to the entire organism.
FALSE
A mutation in a gene that results in it being expressed in the wrong place or at the wrong time is known as a _____________________ mutation.
GAIN OF FUNCTION
The question of whether animal eyes have evolved independently in different organisms or have evolved once from a single organism and then diverged over time is still being actively investigated by evolutionary scientists.
TRUE
Which statement about the differentiation of the three primary germ layers is not correct?
Ectoderm gives rise to cells lining the digestive tract and lungs, as well as liver and pancreas.
