Multiple factors regulate flowering in Arabidopsis. FT mRNA is expressed in companion cells of the leaf vein in response to multiple signals, including day length, light quality, and temperature. FT moves in the phloem from leaves to the apical meristem. FT is unloaded from the phloem in the meristem and interacts with FD.

FT-FD complex activates multiple genes. Which of the following combination is correct?(SS)

#Question id: 2230

#Unit 2. Cellular Organization

Which of these statements about the composition of biological membranes is false?

#Question id: 2231

#Unit 2. Cellular Organization

Membrane proteins:

I) are sometimes covalently attached to lipid moieties.

II) are sometimes covalently attached to carbohydrate moieties.

III) are composed of the same 20 amino acids found in soluble proteins.

IV) move across the membrane unless they are anchored

Which of the following combination is correct?

#Question id: 2232

#Unit 2. Cellular Organization

A GPI anchor

a. serves to attach some proteins to the cytosolic face of the plasma membrane.

b. contains phosphotidylserine.                      

c. may be cleaved to release the protein from the membrane.

d. contains sugar residues in addition to lipid components.

e. contains phosphoethanolamine.

#Question id: 2233

#Unit 2. Cellular Organization

Membrane proteins may interact with biomembranes through

a. covalently attached fatty acid molecules.

b. covalently attached lipid molecules.

c. noncovalent protein-protein interactions.

d. hydrophobic α-helical domains.

e. noncovalent protein-lipid interactions.

#Question id: 2234

#Unit 2. Cellular Organization

Which of the following statement(s) is (are) true of transmembrane proteins?

a. All contains a hydrophobic α helix.

b. Some serve as membrane attachment sites for peripheral membrane proteins.

c. Some contain more than one membrane-spanning domain.

d. All are asymmetrically oriented in the lipid bilayer.

#Question id: 2235

#Unit 2. Cellular Organization

The generation and maintenance of a membrane electric potential requires which of the following:

a. active pumping of ions       

b. ion-specific membrane channel proteins

c. ATP                                    

d. a generally permeable membrane