Question

Imagine phase portrait arrows that start directly on the zero growth isocline for the pathogen(the orange line). The orientation of these arrows would be:

1) Vertical
2) Horizontal
3) Sometimes vertical and sometimes horizontal
4) At an angle

Answer 1

The orientation of phase portrait arrows on the zero growth isocline for a pathogen would be horizontal or possibly at an angle, but not vertical since vertical arrows would imply a change in population size, which does not occur on the zero growth isocline.

Step-by-step explanation:

The orientation of the phase portrait arrows that start directly on the zero growth isocline for the pathogen would be either horizontal or at an angle. They would not be vertical because that would indicate an increase or decrease in the pathogen population, which contradicts the zero growth condition on the isocline. In the context of viral growth, particularly that of bacteriophages, a steep increase does occur, but it is after the burst size stage, where many new virions are released from the host cell. This is part of the one-step multiplication curve and not the initial zero growth phase represented by the isocline.

When considering the direction of growth in the phase portrait, environmental factors and interactions with other components of the system could result in arrows pointing in various directions, but not vertical on the zero growth isocline itself. The direction would likely be horizontal if there is no change in the pathogen population, or angled if there is a simultaneous change in multiple factors.