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TLS Online TPP Program

#Question id: 16147

 Which statement is not true for Natural killer (NK) cells?

#Unit 4. Cell Communication and Cell Signaling
  1. Natural killer (NK) cells are lymphoid cells that are closely related to B and T cells. However, they do not express antigen specific receptors and are considered part of the innate immune system.
  2. They are distinguished by the expression of a surface marker known as NK1.1, as well as the presence of cytotoxic granules. Once referred to as “large granular lymphocytes” because of their appearance under a microscope.
  3.  NK cells constitute 5% to 10% of lymphocytes in human peripheral blood. Th ey are effi cient cell killers and attack a variety of abnormal cells, including some tumor cells and some cells infected with virus.
  4. They distinguish cells that should be killed from normal cells in a very clever way: by “recognizing” the absence of MHC class II, which is expressed by almost all normal cells, but is specifically down-regulated by some tumors and in response to some viral infections.
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TLS Online TPP Program

#Question id: 18006

#Unit 11. Evolution and Behavior

During which geological period origin, first forests; lands plants well established?
TLS Online TPP Program

#Question id: 363

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the pH of a mixture of 0.042 M NaH2PO4 and 0.058 M Na2HPO4? If 1.0 mL of 10.0 M NaOH is added to a liter of the buffer prepared, how much will the pH change? (pKa = 6.86)
TLS Online TPP Program

#Question id: 10822

#Unit 10. Ecological Principles

When two organisms attempt to utilize the same resource, the result is:
TLS Online TPP Program

#Question id: 1374

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to gap junctions.

i. Vertebrate gap junctions are composed of connexins, a family of structurally related transmembrane proteins with molecular weights between 26,000 and 60,000.

ii. Each vertebrate hexagonal particle consists of six noncovalently associated connexin molecules. Each individual connexin molecule has two membrane-spanning α helices with a topology similar to that of claudin.

iii. The permeability of gap junctions is regulated by posttranslational modification of connexins (e.g., phosphorylation) and is sensitive to changes in environmental conditions

such as intracellular pH and Ca2+ concentration, membrane potential, and the intercellular potential between adjacent interconnected cells (“voltage gating”).

iv. The assembly of connexins, their trafficking within cells, and the formation of functional gap junctions apparently depend on N-cadherin and its associated adapter proteins as well as desmosomal proteins.

Which of the following statements are correct?
TLS Online TPP Program

#Question id: 12949

#Unit 7. System Physiology – Animal

At which renal tubular sites would the concentration of creatinine be expected to be highest in a normally hydrated person?