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: 12106

#Unit 10. Ecological Principles

#Question id: 12108

#Unit 10. Ecological Principles

#Question id: 10234

#Unit 10. Ecological Principles

You observed the two species of barnacles, species 1 and species 2, occupy upper and lower strata of intertidal rocks, respectively. Only when species 1 was removed by you from the upper strata, species 2 could occupy both the upper and lower strata. From the choice given below what would be your inference from these observations.

#Question id: 10235

#Unit 10. Ecological Principles

Following some observation is correct about species of P, Q and R

A) Species P and R have generalized nich while Q has specialized nich

B) Species P and R have specialized nich while Q has generalized nich

C) Species P and R are more prone to extinct than Q species

D) Species Q is more prone to extinct than either P or R species

#Question id: 10236

#Unit 10. Ecological Principles

Following figure represent fundamental and realized nich of species P and Q in gradient of temperature along sea shore. which of the following statement are correct? 

A) Fundamental niche of species P is greater than its realized nich

 B) Fundamental niche of species Q is greater than its realized nich

 C) Species Q is strong competitor than species P

 D) There is no effect on spaced occupied by Q in the presence or absence of species P

#Question id: 10237

#Unit 10. Ecological Principles

Which of the following is the most logical conclusion about the distribution of the two species of barnacle, Chthamalus and Balanus?