The ability of a population of fibroblasts to migrate along the surface of a tissue culture dish depends on adhesion between the cell surface and the extracellular matrix molecules coating the dish. The dish is coated with laminin, and the only cell-surface protein capable of binding laminin is a cell-adhesion protein called an integrin. Integrins are integral plasma-membrane proteins that function as heterodimers. Under these conditions the rate at which a fibroblast can migrate along the laminin coated culture dish is proportional to the strength of adhesion between the cell and the laminin substrate. The table below lists the rate of cell migration observed for fibroblasts genetically engineered to generate the indicated phenotypes. One explanation for the effect of overexpression of the cytoplasmic domain of the integrin beta subunit is that this domain normally functions to bind a cytoplasmic factor necessary for integrin function. Which of the following would be the most informative experiment to identify the cytoplasmic factor?

#Question id: 13198

#Unit 6. System Physiology – Plant

#Question id: 11806

#Unit 6. System Physiology – Plant

sap is translocated from areas of supply, called sources, to areas of metabolism or storage, called sinks. Which of the following statements about source and sink are TRUE?

a.) Sinks include any nonphotosynthetic organs of the plant and organs that do not produce enough photosynthetic products to support their own growth or storage needs

b.) Sources include exporting organs that are capable of producing photosynthate in excess of their own needs

c.) During the growing season of the first year, storage root is a sink, when it accumulates sugars received from the source leaves. During the second growing season the same root becomes a source

d.) Roots, tubers, developing fruits, and immature leaves, which must import carbohydrate for normal development, are all examples of sources tissues

Find the correct combination of the source and sink pattern of translocation.

#Question id: 10553

#Unit 6. System Physiology – Plant

Cell walls allow plant cells to build up large internal hydrostatic pressures called

#Question id: 10554

#Unit 6. System Physiology – Plant

Transpiration is an important means of dissipating the heat input from sunlight, Heat dissipates because the water molecules that escape into the atmosphere

#Question id: 10555

#Unit 6. System Physiology – Plant

The water molecule, hydrogen–oxygen bonds form an angle of 105°, The opposite partial charges (δ– and δ+) on the water molecule lead to the formation of which bond with other water molecules,

#Question id: 10557

#Unit 6. System Physiology – Plant

The attraction of water to a solid phase such as a cell wall or glass surface known as