Answer:
The correct answer will be option-C
Explanation:
The rhythm of the heartbeat is controlled by the pacemaker of the heart called the sino-atrial node.
The SA node generates action potentials which trigger the contraction and relaxation of the atrium and ventricles. The membrane potential generation initiates by the depolarization of the cell membrane when the L type of Ca⁺² ions opens up and calcium ions enter the cell.
This depolarizes the cell until the potential threshold is reached which lies between the -40 and -30 mV.
Thus, Option-C is the correct answer.
Answer:
Explanation:
The nitrogen cycle is an important cycle to the atmosphere. Nitrogen is an essential part of biological molecules such as proteins and nucleic acid, which makes nitrogen essential for all living organisms. Nitrogen makes up 78 percent of the atmosphere.
Answer:
Mutation is important as the first step of evolution because it creates a new DNA sequence for a particular gene, creating a new allele.
Explanation:
Answer: C. Radical global climate change.
Explanation:
The entire taxa of the species can be wiped out due to an large catastrophic event associated with the change in the climate. As the climate becomes warm the chances of undergoing the global precipitation rate will change. The climate being an important abiotic factor under unstability is likely to affect the amount of rainfall, snow fall, drought and conditions of desertification. All these factors can be responsible for the removal of the entire taxa of the species in short time.
It could occur after a forest fire or flood.
