Explain why the transport of molecules across the cell membrane is considered to be both specific and directional
What will be an ideal response?
ANSWER: Transport is considered directional because only certain ions and molecules can move into
the cell, while others can only move out of the cell. Transport is specific because only certain
ions and molecules can actually move across the membrane.
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Archaeopteris, the first known tree, has all of the following characteristics EXCEPT:
A. occurred in forests B. contained wood C. had a eustele D. had a vascular cambium E. reproduced by seeds
Stool specimens suspected of containing which of the following enteric pathogens should be collected and transported only in Cary-Blair medium because buffered glycerol saline is toxic for this bacterium?
a. Vibrio b. Salmonella c. Shigella d. Plesiomonas
Choose the function that best matches to each item.
A) GC and CAAT boxes B) message containing information for a gene C) multiprotein complex associated with augmentation of transcription of a particular gene D) transcribed and translated continually in a cell E) increases frequency of transcription of a particular gene F) enhancer-associated transcription factors G) regulatory protein allows transcription H) message containing information for multiple genes I) inhibits transcription of a particular gene J) transcribed and translated at certain times in a cell K) control expression of other genes essential in development L) enhancer-associated translation factors M) regulatory protein prevents transcription 1) activators 2) homeotic genes 3) silencer 4) polygenic mRNA 5) enhancer 6) enhanceosome 7) negative gene control 8) constitutive gene 9) positive gene control 10) proximal control elements
The distal convoluted tubule
A. reabsorbs glucose. B. secretes water. C. increases the amount of protein in the nephron. D. regulates ions.