#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?
#Question id: 11342
#Unit 2. Cellular Organization
What happens to K+ transport by valinomycin when the membrane is cooled below its transition temperature?
#Question id: 14475
#Unit 13. Methods in Biology
#Question id: 9165
#Unit 9. Diversity of Life Forms
Which of the following biomes spans the largest annual mean temperature range, but the narrowest mean precipitation range?
#Question id: 3859
#Unit 3. Fundamental Processes
Polyadenylation is: