Several transport steps are involved in the movement of photosynthate from the mesophyll chloroplasts to the sieve elements of mature leaves; The following steps are invoved with sucrose transportation is given;

a) During the day, triose phosphate is transported from the chloroplast to the cytosol, where it is converted to sucrose.

b) During the night, carbon from stored starch exits the cytosol primarily in the form of maltose and is converted to sucrose

c) Sucrose moves from the mesophyll cells to the sieve elements in the smallest veins of the leaf. This is called short-distance transport pathway

d) With respect to unloading, sucrose and other solutes are translocated away from the source through the vascular system to the sink is referred to as long-distance transport

Which of the following combination is correct?

#Question id: 2001

#Unit 4. Cell Communication and Cell Signaling

A researcher is analyzing the immune response of a patient following the patientʹs exposure to an unknown agent while out of the country. The patientʹs blood is found to have a high proportion of lymphocytes with CD8 surface proteins. What is the likely cause?

#Question id: 2002

#Unit 4. Cell Communication and Cell Signaling

What accounts for antibody switching (i.e., the switch of one B cell from producing one class of antibody to another antibody class that is responsive to the same antigen)?

#Question id: 2003

#Unit 4. Cell Communication and Cell Signaling

The number of MHC protein combinations possible in a given population is enormous. However, an individual in that population has only a couple of MHC possibilities. Why?

#Question id: 2004

#Unit 4. Cell Communication and Cell Signaling

A bone marrow transplant may not be appropriate from a given donor (Jane) to a given recipient (Janeʹs cousin Bob), even though Jane has previously given blood for one of Bobʹs needed transfusions. Which of the following might account for this?

#Question id: 2005

#Unit 4. Cell Communication and Cell Signaling

A transfusion of type A blood given to a person who has type O blood would result in which of the following?

#Question id: 2006

#Unit 4. Cell Communication and Cell Signaling

In Cases 1 and 2 in the table, the mothers would be able, if needed, to supply blood to the newborn even 7-9 months after birth; the same would not be true for Case 3. Why?