Answer:
The answer is Eurasia, North America, Africa, and South America.
Explanation:
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Dispersal helps different species to increase their range of places, thereby helping to increase their population size in different regions. Dispersal also helps to avoid crowding of diseases of a single location as species move to different locations.
<h3>What is dispersal?</h3>
- Dispersal is the act of distributing things over a large area. It is when the individuals or seeds move from one site to their growing site.
- Dispersal can be active (move by oneself) or passive (require dispersers).
- Seed dispersal is the mechanism of transport of plant seeds to new sites for germination and the establishment of new individuals and colonies.
- This depends upon the effectiveness of the seed dispersers.
- Seed dispersal occurs by wind, water, animals, bats, explosions or gravity of the earth.
- Dispersal of seeds is very important for the survival of plant species.
- If the plants of same type grow too closely, they have to compete with each other for light, water and nutrients from the soil.
- Seed dispersal allows plants to spread out from a wide area and avoid competing with one another for the same resources.
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Answer:
Explanation:
The cell membrane separates the cell from the outer environment. The extracellular fluid contains the sodium ions (Na+), chloride ions (Cl-), while intracellular fluid contains potassium (K +) and negative anions.
The potential difference arises when the membrane is selectively permeable to some ions. The resting potential is -70mV.
When the neurons get excited, the sodium ions start to enter by sodium channels.
Now there are more positive ions inside the cell membrane. It disturbs the resting potential i.e. -70mV. This stage is known as depolarization.
When the inside environment of the cell is more positively charged, the potassium ions start to move out of the cell. It goes out by the voltage-gated channels. Thus resting stage is maintained and it is known as repolarization.
But the initial stability of the cell membrane has to be maintained. To restore the resting stage, the sodium ions start to move out of the membrane and potassium ions enter into the cells again. This is an active transport and has done by the Na+ - K+ pump. Here 3 sodium ions move out and 2 potassium ions pumped into the cell through the plasma membrane.
Thus the resting potential regains. The potassium ions come back into the cells against the concentration gradient and ATP provides the energy for this phenomena.
