This feature is an adaptive, as the redistribution of chloroplasts within the cells modulates light absorption and prevents photodamage, diagram shows of chloroplast distribution patterns in Arabidopsis palisade cells in response to different light intensities;

                                        

m) A-low light, B-high light, C-darkness

n) A-high light, B-darkness, C-low light

Based on the above light intensities, each shows different chloroplasts position such as,

i) chloroplasts avoid sunlight by migrating to the side walls of palisade cells

ii) chloroplasts move to the bottom of the cell, although the physiological function of this position is unclear

iii) chloroplasts optimize light absorption by accumulating at the upper and lower sides of palisade cells

Which of the following correct combinations shows light intensities and chloroplast movements?

#Question id: 1395

#Unit 4. Cell Communication and Cell Signaling

Which of the following mutations would promote malignancy in cells whose proliferation is inhibited by TGFβ?

a. overexpression of Smad2               

b. loss of Smad 4

c. overexpression of TGFβ receptor I

d. loss of TGFβ receptor II

#Question id: 1396

#Unit 4. Cell Communication and Cell Signaling

Trks are:

a. endonucleases.        b. transmembrane receptors.   c. proteases.     d. protein kinases.      

#Question id: 1397

#Unit 4. Cell Communication and Cell Signaling

The vertebrate equivalent of CED-9 is:

#Question id: 1398

#Unit 4. Cell Communication and Cell Signaling

Which of the following properties is (are) characteristic of a benign tumor?

a. well differentiated              b. localized to tissue of origin             c. metastatic               

d. promotes angiogenesis        e. surrounded by a fibrous capsule

#Question id: 1399

#Unit 4. Cell Communication and Cell Signaling

Loss-of-function mutations in which of the following genes typifies colorectal carcinomas?

a. myc              b. K-ras                       c. p53              d. APC

#Question id: 1400

#Unit 4. Cell Communication and Cell Signaling

Which property is shared by malignant tumor cells and transformed cells in culture?

a. reduced growth factor requirement                        b. attachment-dependent growth

c. loss of actin microfilaments                                    d. altered morphology