TLS Online TPP Program

#Question id: 11204


Why do Na+ ions enter the cell when voltage-gated Na+ channels are opened in neurons?

#Unit 7. System Physiology – Animal
  1. because the Na+ concentration is much lower outside the cell than it is inside

  2. because the Na+ ions are actively transported by the sodium-potassium pump into the cell
  3. because the Na+ concentration is much higher outside the cell than it is inside, and the Na+ ions are attracted to the negatively charged interior

  4. because the Na+ concentration is much higher outside the cell than it is inside, and the Na+ ions are actively transported by the sodium-potassium pump into the cell

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TLS Online TPP Program

#Question id: 13191

#Unit 10. Ecological Principles

Which of the following statements about circadian rhythms is correct?

TLS Online TPP Program

#Question id: 13190

#Unit 10. Ecological Principles

During the evolution of life on Earth, the photosynthetic organisms initially responsible for raising atmospheric oxygen concentrations from less than 1 percent to about 20 percent were

TLS Online TPP Program

#Question id: 13189

#Unit 10. Ecological Principles

The relative abundance of C plant species increases with latitude because of the associated temperature gradient. A study in North America found that at  42°  North,  C3  plants  become more  abundant than  C4  plants. Given  an  increase in  mean global  temperatures by  10°C and no  other changes in  environmental conditions,  the latitude at which C3 plants become more abundant:

TLS Online TPP Program

#Question id: 13188

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance


Which of the following factors is most likely to generate the seed survivorship curve shown? 

TLS Online TPP Program

#Question id: 13187

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance


Which of the following factors is most likely to generate the seed density curve shown? 

TLS Online TPP Program

#Question id: 13186

#Unit 10. Ecological Principles

The following figure is a model of seedling establishment as a function of distance from a parent tree. Initial seed density measures the number of seeds falling to the ground. Seed survivorship measures the proportion of seeds that survive to the adult stage at each distance

This model predicts that recruitment of new individuals into the population should be