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: 10332

#Unit 9. Diversity of Life Forms

The four-chambered hearts of birds and the four-chambered hearts of mammals evolved independently of each other. If one were unaware of this independence, then one might logically conclude that

#Question id: 12419

#Unit 10. Ecological Principles

#Question id: 3044

#Unit 2. Cellular Organization

If the pH indicator were left out of MacConkey agar, the medium would be

#Question id: 4081

#Unit 3. Fundamental Processes

Which of the following regulatory scenarios of cell-type-specific expression of fibronectin isoforms in humans is (are) consistent with information on known splicing factors?

a. A Tra-like splicing factor expressed in fibroblasts is required for inclusion of EIIIA and EIIIB exons.

b. An Sxl-like splicing factor is required in hepatocytes for exclusion of EIIIA and EIIIB exons.

c. A Tra-2-like factor enhances binding of the cleavage/polyadenylation complex in fibroblasts.

d. A Dsx-like protein is required to inhibit transcription of the fibronectin gene.

#Question id: 10687

#Unit 10. Ecological Principles

V(t) and E(t) are, respectively, prey density and predator density at time t. The densities have dynamics

What will the positive equilibrium densities of both predator and pray at isocline