The first single-celled organisms appeared around 3.5 ________ years ago
Fill in the blank(s) with correct word
billion
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The TATA box is a key element of the ____ of most eukaryotic protein-coding genes
a. terminator b. coding region c. promoter d. transcription start point e. introns
The ________ is comprised of the semifluid portion of the cell and contains the organelles
Fill in the blank with correct word.
The major obstacle to the use of xenotransplants is ________________
A. not enough human donors B. finding the right sized animals C. resistance from opponents of genetically modified animals D. organ rejection by recipients E. more than one of these
Why are epithelial membranes not very thick?
A. Epithelial tissues can only reach a certain thickness because their growth is constrained by microtubules inside the cell membrane. B. Thick epithelial tissues would collapse due to the drying effect of the environment. C. Epithelial tissues are required to support other cells growing on top of the tissue. D. Epithelial tissues are programmed to stop dividing after only a few cell cycles. E. Epithelial tissues play a critical role in transport, and must be thin to allow diffusion to occur.