According to pressure-flow theory, how does sap move from the sieve tube into a sink?
A. a positive pump pressure
B. osmosis of the dissolved sugars across the sieve tube and the sink plasma membranes
C. a negative pump pressure
D. gravitational action as phloem moves down from the source
E. active membrane transport through the plasma membranes
A. a positive pump pressure
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The helical shape of the DNA contains major and minor grooves, which assist in the regulating of gene expression
Indicate whether the statement is true or false
The retinoblastoma protein (pRB), like p53, serves as a(n) ________ in regulating the cell cycle
A) up regulator B) tumor suppressor C) tumor enhancer D) oncogene E) pseudooncogene
Blood displays a bright red color when
A) oxygen is released by hemoglobin as blood travels through capillaries. B) four oxygen molecules bind to hemoglobin to create oxyhemoglobin. C) plasma albumin levels increase as blood goes through the lungs. D) carbon dioxide binds to the heme group of hemoglobin. E) deoxyhemoglobin is formed in blood plasma.
Answer the following questions true (T) or false (F)
1. The CRISPR-Cas9 gene editing system so far can only be used to alter prokaryotic cells. 2. Vaccines are only necessary for infants and children. 3. The more closely a vaccination agent resembles the actual infectious agent, the more likely a strong adaptive immune response will be elicited.