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TLS Online TPP Program

#Question id: 12083

In bottom sediments of lakes and streams, organic matter is broken down by heterotrophic microorganisms and ammonia is released. Under aerobic conditions, specialized bacteria convert ammonia to nitrate (nitrification). This nitrate, together with nitrate from other sources, diffuses into the deeper sediments, where it may undergo anaerobic conversion to nitrogen gas (denitrification). These sediments typically contain oligochaete worms that live with their heads buried and their tails waving back and forth in the overlying water. Plastic columns were packed with freshly collected stream sediments and then  covered  with  layers  of  nitrate enriched  water.  A similar  set  of  columns  was packed with sediment that had been sterilized and then covered with either nitrate-enriched water or distilled water. Oligochaete  worms  were  collected  and  acclimated  to  20°(C)Following  acclimation,  worms  were  rinsed  in  distilled water and then added to three sediment columns. The columns were incubated in the dark at 20°C and monitored every three days for changes in the concentration of nitrate in the overlying water. Nitrate concentrations in each of the experimental treatments were plotted against time, as shown in the graph below

It can be concluded from the figure that

#Unit 10. Ecological Principles
  1. The presence of o1igochaete worms increases the rate of denitrification
  2. The presence of oligochaete worms decreases the rate of denitrification
  3. The presence of sediment microorganisms decreases the rate of denitrification
  4. Oligochaete worms carry out denitrification in the absence of sediment microorganisms
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TLS Online TPP Program

#Question id: 16142

#Unit 4. Cell Communication and Cell Signaling

Stem cells are defined by two capacities:
(1) the ability to regenerate or “self-renew” and
(2) the ability to differentiate into all diverse cell types. Embryonic stem cells have the capacity to generate every specialized cell type in an organism, in other words,
TLS Online TPP Program

#Question id: 16141

#Unit 4. Cell Communication and Cell Signaling

Indicate to which branch of the immune system the following statements apply, using H for the humoral branch and CM for the cell-mediated branch. Which cells involve in both response?
TLS Online TPP Program

#Question id: 15850

#Unit 4. Cell Communication and Cell Signaling

For innate and adaptive immunity to work together, these two systems must be able to communicate with one another. This communication is achieved by both cell-cell contact and by soluble messengers. Most of these soluble proteins are growth factor–like molecules known by the general name cytokines. Which of these molecule can work as communicator between innate and adaptive immunity?
TLS Online TPP Program

#Question id: 15849

#Unit 4. Cell Communication and Cell Signaling

Host-pathogen interactions are an ongoing arms race; pathogens evolve to express unique structures that avoid host detection, and the host germline-encoded recognition system co-evolves to match these new challenges. However, because pathogens generally have much shorter life cycles than their vertebrate hosts, and some utilize error-prone DNA polymerases to replicate their genomes, pathogens can evolve rapidly to evade host encoded recognition systems. Which error prone DNA polymerase is used  by human?
TLS Online TPP Program

#Question id: 15848

#Unit 4. Cell Communication and Cell Signaling

viruses frequently expose unique chemical structures only during their replication inside host cells. Many of these can be detected via intracellular receptors that bind exposed chemical moieties while still inside the host cell. This can trigger an immediate antiviral response in the infected cell that blocks further virus replication. At the same time, this initiates the secretion of chemical warning signals sent to nearby cells to help them guard against infection (a neighborhood watch system!). virus is not recognised which receptor?
TLS Online TPP Program

#Question id: 15847

#Unit 4. Cell Communication and Cell Signaling

Pathogen-associated molecular patterns (or PAMPs) are common foreign structures that characterize whole groups of pathogens. It is these unique antigenic structures that the immune system frequently recognizes first. Animals, both invertebrates and vertebrates, have evolved to express several types of cell surface and soluble proteins that quickly recognize many of these PAMPs; a form of pathogen profiling. For example, encapsulated bacteria possess a polysaccharide coat with a unique chemical structure that is not found on other bacterial or human cells. White blood cells naturally express a variety of receptors, collectively referred to as pattern recognition receptors (PRRs), that specifically recognize these sugar residues, sugar residues is recognised by?