Because if we're simultaneously moving/manipulating two different variables it can be very hard to determine why one variable is changing and why the other is changing. While this can be done with more complicated experimental designs, it usually is the case that scientists will only manipulate one variable and not two different ones.
Answer:
Option-C
Explanation:
Action potential refers to the generation of electrical activity due to the influx and efflux of ions in the cell.
The cell which transmits the action potential is known as the neuron and the neuron maintains the membrane potential at -70 mv. The influx of sodium ions causes depolarization when it crosses the threshold value.
The generated action potential now travels in the neuron through its long tubular structure called an axon. The axon transmits the signal from the cell body towards the axon terminal and thus is known as the down the axon.
Thus, Option-C is the correct answer.
Answer: The correct option is A.
Biosphere and ecosystems
Explanation:
This is because Biosphere and ecosystems include non living things and biosphere is the layer of the ecosystem that consist of both living and non living things.
Ecosystem consist of a area which consist of living things like plants, animals e t.c interacting with the non living part of the environment I e physical part which include temperature, soil e.t.c.