In given Relationship of oxygen production to flash energy, the first evidence for the interaction between the antenna pigments and the reaction centre, What conclusion can be drawn about based on graph;

a.) several hundred pigments are associated with each reaction centre and that each reaction centre must operate four times to produce 1 molecule of oxygen—hence the value of 2500 chlorophylls per O2

b.) low light intensity of the curve, an increase in the number of photons stimulates a proportional increase in oxygen evolution. Thus, the slope of the curve measures the quantum yield for oxygen production

c.) The quantum yield for a particular process can range from 0 →if that process does not respond to light to 1.0→if every photon absorbed contributes to the process by forming a product

d.) O2 require more than a single photochemical event to be formed, and therefore have a lower quantum yield of formation than the photochemical quantum yield. It takes about ten photons to produce one molecule of O2, so the quantum yield of O2 production is about 0.1

Which of the following statements would be correct relates with graph?

#Question id: 1377

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements apply to both eukaryotic cell walls and animal cell extracellular matrices? Please select all that apply.

a) They are inflexible structures that support cells.

b) They are built to a common overall structure that can be described as 'fibres in a matrix'.

c) Their protein components are synthesized by ribosomes of the rough endoplasmic reticulum.

d) They limit the diffusion of ions and small molecules into the cell.

#Question id: 1378

#Unit 4. Cell Communication and Cell Signaling

Which of the following apply to fibronectins? Please select all that apply.

a) They are disulphide linked dimers, with each polypeptide composed of a number of binding domains joined together by short flexible segments.

b) They have an essential role in linking the extracellular matrix to its underlying cells.

c) Like integrins, fibronectins are directly connected to the cytoskeleton.

d) They participate in 'inside out' and 'outside in' signalling mechanisms.

#Question id: 1379

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements apply to cellulose? Please select all that apply.

a) It is a polyglucose containing beta 1-6 glycosidic bonds.

b) It is a major component of plant cell walls

c) It is a polyglucose containing beta 1-4 glycosidic bonds.

d) It is a major component of Gram negative cell walls.

#Question id: 1380

#Unit 4. Cell Communication and Cell Signaling

Which of the following apply to the synthesis of plant cell walls? Please select all that apply.

a) Cellulose microfibrils are formed by cellulose synthase complexes called rosettes

b) Cellulose is synthesized using cytoplasmic ATP-glucose and deposited as microfibrils directly on the outer surface of the plasma membrane.

c) Matrix polysaccharides of plant cell walls are synthesized in the Golgi apparatus and exported to the cell wall by endocytosis.

d) The direction of cellulose microfibril growth is determined by the orientation of arrays of microtubules lying just below the plasma membrane.

#Question id: 1381

#Unit 4. Cell Communication and Cell Signaling

Match each definition with given terms

#Question id: 1382

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to cell-cell and cell–extracellular matrix junctions and their adhesion molecules.

A. Adherens junctions and desmosomes are integrin-containing anchoring junctions that bind the membranes of adjacent cells, giving strength and rigidity to the entire tissue.

B. Hemidesmosomes are cadherin-containing anchoring junctions that attach cells to elements of the underlying extracellular matrix.

C. Integrins are a large family of αβ heterodimeric cell-surface proteins that mediate both cell-cell and cell-matrix adhesions and inside-out and outside-in signaling in numerous tissues.

D. Tight junctions block the diffusion of proteins and some lipids in the plane of the plasma membrane, contributing to the polarity of epithelial cells. They also limit and regulate the extracellular (paracellular) flow of water and solutes from one side of the epithelium to the other.

Which of the following statements are incorrect?