Answer:
The simultaneous effect of a predator population on a prey population and a prey population on a predator population over time.
Explanation:
The mathematical models of Lotka-Volterra equations explain the existing interaction between species in which prey and predator influence and affect each other. The model follows a few assumptions,
- The ecosystem is isolated and closed. There is no migration.
- The whole individuals are reproductively equivalent.
- In the absence of the predator, prey shows an exponential growth rate. The prey is in the ideal environment.
- When there is no prey, the predator population decreases exponentially because of the lack of food. The predator environment is ideal, but it is limited by prey density.
- The predation rate is proportional to the encounters rate, which also depends on density.
- The predators affect the prey populations, inducing its decrease proportionally to the number of prey and predators present.
- The prey population also influences the predator population proportionally to the number of encounters between the two species.
In these equations, the variable D is the number of predators, and P the number of prey items.
The parameters are always constant:
• r1: prey growth rate.
• a1: predator hunting success.
• r2: predator growth rate.
• a2: the success of the predator in hunting and feeding.
In nature, many factors affect interactions, such as dense-dependent factors and dense-independent factors. Also, in reality, there are stochastic factors. Stochasticity refers to the variability in the system involving those factors that are affecting or influencing population growth. Stochasticity might be related to good years and bad years for population growth.
In real situations, the compliance of the whole assumption does not occur. The previously mentioned constants might vary, constantly changing the interaction between the predator and the prey. These parameters change in different degrees, resulting in varying circumstances for both species.
Answer:
- hyperpolarization
- depolarization
- hyperpolarization
- depolarization
- hyperpolarization
- depolarization
- depolarization
Explanation:
The resting membrane potential is balanced by ion leakage and ion pumping, to get an electrical signal started the membrane potential has to lose its balance. This starts with a membrane channel opening for Na+ since Na+ concentration is higher outside the cell, ions will rush into the cell. This will change the relative voltage inside the cell. The resting potential has a voltage of -70 mV, the sodium cation entering the cell cause it to become less negative. <em>This is known as depolarization.</em>
The concentration gradient for Na+ will continue to enter the cell making the voltage to become positive reaching +30 mV. At the same time, this happens, other voltage-gated channels are also opening, a concentration gradient acts on K+, as well, as it leaves the cell, it takes a positive charge with it making the membrane potential to move back to its resting voltage of -70 mV. <em>This is called repolarization. </em>
For potassium ions to reach equilibrium the membrane voltage needs to be below -70 mV, this leads to a period of <em>hyperpolarization</em> that occurs while the K+ channels are open.
I annexed an image that illustrates this action potential process.
<em>Considering the information given during depolarization there's an increase in the number of sodium leak channels (7) making the inside of the cell more positive (2) increase in the membrane potential (4), this also implies a decrease in the extracellular concentration of potassium (6)</em>
<em>Meanwhile, during hyperpolarization an increase in the extracellular concentration of potassium (3) decreases the membrane potential (1) making the inside of the cell more negative (5).</em>
I hope you find this information useful and interesting! Good luck!<em>
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