The herbaceous plant Achillea lanulosa is widespread in the Northern Hemisphere. Phenotypic variation in the species has been extensively studied along an altitudinal gradient from sea level to over 3,000 meters. In California there is conspicuous variation in  height; alpine plants are only several centimeters tall  while  those in  the San Joaquin Valley may reach a height of 1.8 meters. Adaptation to different local environments also results in variation in physiological processes such as photosynthetic rate, resistance to cold, and the timing of dormancy.

Which of the following methods would be best to determine whether the phenotypic variation in Achillea lanulosa is due to genotypic variation?

TLS Online TPP Program

#Question id: 16954

#Unit 4. Cell Communication and Cell Signaling

match the following

A. endosteal niche	1. versatile cells that both generate bone and control the differentiation of HSCs
B. osteoblasts	2. line the blood vessels and also regulate HSC differentiation
C. reticular cells	3. send processes connecting cells to bone and blood vessels, and, unexpectedly
D. sympathetic neurons	4. can control the release of hematopoietic cells from the bone marrow.

TLS Online TPP Program

#Question id: 16955

#Unit 4. Cell Communication and Cell Signaling

Stage thymocytes express neither CD4 nor CD8, markers associated with mature T cells. They are therefore called double negative (DN) cells. DN cells first travel to the region under the thymic capsule, a region referred to as the ________, where they proliferate and begin to generate their T-cell receptors. Thymocytes that successfully express TCRs begin to express both CD4 and CD8, becoming double positive (DP) cells, and populate the cortex, the site where most (85% or more) immature T cells are found.

TLS Online TPP Program

#Question id: 16956

#Unit 4. Cell Communication and Cell Signaling

Polyclonal antibodies are raised against bovine serum albumin in rabbit. Subsequently IgG in the antiserum is purified and digested with either pepsin or papain. Out of the following possibilities, which one is correct?

TLS Online TPP Program

#Question id: 16957

#Unit 4. Cell Communication and Cell Signaling

the immune system can be summarized as follows. Which is not correct for immune system?

TLS Online TPP Program

#Question id: 16958

#Unit 4. Cell Communication and Cell Signaling

Plasmacytoma or myeloma tumors secrete large amounts of monoclonal antibodies into the serum and tissue fluids of the patients, and these antibodies can be purified in large quantities. Which statement is true for Bence-Jones proteins?

TLS Online TPP Program

#Question id: 16959

#Unit 4. Cell Communication and Cell Signaling

antigenic determinant is defined as a region of an antigen that makes contact with the antigen-combining region on an antibody. Which statement is true for Anti-isotype antibodies?