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TLS Online TPP Program

#Question id: 10699

Two plant species co-occur in a prairie. Species X always occurs near species Y. However, species Y often occurs in isolation from species X and produces more seeds when alone than when growing next to species X. Which of the following interactions between species X and Y could generate this pattern?

#Unit 10. Ecological Principles
  1.  Competition, in which Y is superior to X in accumulating resources
  2. Mutualism, in which both X and Y benefit by exchanging resources
  3. Parasitism, in which X benefits from resources produced by Y and reduces the growth of Y by doing so
  4. Commensalism, in which X benefits from resources produced by Y but does not affect the growth of Y by doing so
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TLS Online TPP Program

#Question id: 16118

#Unit 7. System Physiology – Animal

Following statements are regarding to the heat production by the activation of sympathetic nervous system.
A. Activation is stimulation of β receptors in brown fat, which increases metabolic rate and heat production.
B. Activation is stimulation of α2 receptors in brown fat, which increases metabolic rate and heat production.
C. Stimulation of α1 receptors in vascular smooth muscle of skin blood vessels, producing vasoconstriction. Vasoconstriction reduces blood flow to the surface of the skin.
D. Stimulation of α1 receptors in vascular smooth muscle of skin blood vessels, producing vasodilation. Vasodilation reduces blood flow to the surface of the skin.
Which of the following combination is correct?
TLS Online TPP Program

#Question id: 28164

#Unit 13. Methods in Biology

It is possible to calculate the number of clones that must be present in a gene library to give a probability of obtaining a particular DNA sequence. This correct formula is:
TLS Online TPP Program

#Question id: 5950

#General Aptitude

A non-leap year, find the minimum number of days between one Friday the 13th and the next Friday the 13th?
TLS Online TPP Program

#Question id: 4713

#Unit 11. Evolution and Behavior

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these statements explains why the pigweed reappeared?
TLS Online TPP Program

#Question id: 11588

#Unit 7. System Physiology – Animal

Correct and appropriate signal transduction processes are generally under strong selective pressure and are determined by the properties of the molecules involved, the concentrations of signal and receptor molecules, and the binding affinities between signal and receptor. Therefore, a hormone action is very specific in a species at any one point in time. However, there are examples of very diverse functions of a specific hormone between groups of organisms. For example, thyroxin, which is produced in all vertebrates and many invertebrates, can trigger growth, differentiation, metamorphosis, maturation, reproduction, behavior, temperature tolerance, osmoregulation, or seasonal adaptation depending on the organism in which it is produced. What is the most logical explanation for such different responses triggered by thyroxin in organisms?