#Question id: 376
#Unit 1. Molecules and their Interaction Relevant to Biology
Phosphoric acid is tribasic, with pKa of 2.14, 6.86 and 12.4. The ionic form that predominates at pH 3.2 is
#Question id: 792
#Unit 1. Molecules and their Interaction Relevant to Biology
Which arm of the tRNA can act as a structural recognition feature?
#Question id: 13165
#Unit 5. Developmental Biology
#Question id: 1558
#Unit 4. Cell Communication and Cell Signaling
Work of follicular dendritic cells
#Question id: 10920
#Unit 6. System Physiology – Plant
The pressure-flow model, first proposed by Ernst Münch, Phloem loading at the source and phloem unloading at the sink establish the pressure gradient.
a.) In source tissues, an accumulation of sugars in the sieve elements generates a lower or negative solute potential (ψs).
b.) source tissue, causes a steep drop in the water potential (ψ), due to water potential gradient, water enters the sieve elements and causes turgor pressure (ψp ) decrease.
c.) In sink tissues, phloem unloading leads to a lower sugar concentration in the sieve elements, generating a higher or less negative solute potential.
d.) As the water potential of the phloem rises above that of the xylem, water tends to leave the phloem in response to the water potential gradient, causing a decrease in turgor pressure in the sieve elements of the sink.
Which of the following statements of sink and source tissue is FALSE?