It is now thought that the atmosphere of the primitive Earth was composed largely of carbon dioxide, nitrogen, and water vapor. The composition of certain iron-containing minerals suggests that the carbon dioxide began to be replaced by oxygen about 2 billion years ago.   Which of the following is the best explanation for the change in atmospheric composition?

TLS Online TPP Program

#Question id: 24327

#Unit 4. Cell Communication and Cell Signaling

What is the major roles of Tight junctions in animal cells?

TLS Online TPP Program

#Question id: 24328

#Unit 4. Cell Communication and Cell Signaling

Tight junctions prevent the diffusion of: 

a. Macromolecules

b. Small water-soluble molecules

c. Ions 

d. Membrane proteins 

e. Glycolipids

Choose the correct set of combinations

TLS Online TPP Program

#Question id: 24329

#Unit 4. Cell Communication and Cell Signaling

_______permit the passage of molecules as large as 1.2 nm in diameter (molecules smaller than 1200 Da).

TLS Online TPP Program

#Question id: 24330

#Unit 4. Cell Communication and Cell Signaling

Ions, low-MW precursors of cellular macromolecules, products of intermediary metabolism, & small intracellular signaling molecules can pass from cell to cell through_______?

TLS Online TPP Program

#Question id: 24331

#Unit 4. Cell Communication and Cell Signaling

Select the CORRECT combination by matching the junctions with their principal CAMs or adhesion receptors.

Junctions	Principal CAMs or Adhesion receptors
1. Tight junctions	a. Integrins
2. Gap Junctions	b. Occludin
3. 3-D adhesions	c. Connexin
4. Plasmodesmata	d. Undefined

TLS Online TPP Program

#Question id: 24431

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following option is correct regarding the ATP Synthase

1. ATP Synthase Has Two Functional Domains, Fo and F1

2. It Catalyzes the formation of ATP from ADP and Pi, driven by the flow of protons from the P to the N side of the membrane.

3. ATP synthase produces ATP as protons diffuse back through it from the lumen into the stroma.

4. The molecular structure of the mitochondrial ATP synthase has been determined by X-ray crystallography.