Answer:
B. Synaptic vesicle—neurotransmitter—ion channels—end plate potential
Explanation:
When an impulse reaches the synaptic knob, it stimulates the vesicles to move towards the pre-synaptic membrane releasing the acetylcholine(neurotransmitter). This transmitter substance makes the membrane permeable. The transmitter substance then diffuses across the synaptic cleft to the post-synaptic membrane which then becomes depolarised. Sodium ions from cleft then flow through the post-synaptic membrane into the post-synaptic knob causing an action potential at this point. This action potential is then transmitted as a nerve impulse along the neurone. End-plate potential is a change in electrical potential that is chemically induced at the motor neurone leading to muscle contraction because a nerve impulse has reached the nerve endings.
If they test more than one variable, they wouldn't know if it was both variables or one variable that was responsible for any observed effect.
Answer:
Polyploidy
Explanation:
Polyploidy can be defined as a rapid method of speciation that has been important in the history of flowering plants.
In plants, it involves the possession of two complete sets of chromosomes and it leads to the origin of new species.
Hence, the two sets of chromosomes comprises of triploidy (69 chromosomes) and tetraploidy (92 chromosomes).
The right atrium<span> is one of the four chambers of the heart. The heart is comprised of two </span>atria<span> and two ventricles. Blood enters the heart through the two </span>atria<span> and exits through the two ventricles. Deoxygenated blood enters the</span>right atrium<span> through the inferior and superior vena cava</span>