Down;s syndrome is also known as trisomy 21 because it is caused by an additional copy of chromosome 21. The correct answer is the third one: 21st.
Use Absolute Mag™ Biotin Iron Oxide Nanoparticles, 5 nm for fast, easy, and consistent DNA/RNA Purification, Antibody/Protein Purification, Cell Isolation. https://www.cd-bioparticles.com/p/Absolute-Mag%E2%84%A2-Biotin-Iron-Oxide-Nanoparticles-5-nm_20_194_227_5000.html
I'm 100% Confident it's (A) <span>All modern humans evolved from one group of African H. sapiens.
</span>
Answer:
D) Na+ is used to repolarize the membrane.
Explanation:
Option D is wrong choice because it is K+ which is used to repolarize the membrane not Na+.
As soon as membrane gets depolarized because of influx of Na+ due to opening of voltage gated Na+ channels simultaneous opening of voltage gated K+ channels and closing of Na+ voltage gated channels takes place. As a result of which K+ moves out of the cell leading to drawing of electrochemical gradient out of the cell.
In order to achieve resting membrane potential, more Na+ must be out of the cell and more K+ must be inside the cell. There are many leaky channels on neurons from which Na+ has tendency to leak into the cell while K+ has the tendency to leak outside of the cell. So Na+/K+ pump which is located on the membrane of neuron keeps pushing Na+ outside of the cell and K+ inside the cell so as to maintain resting membrane potential which is -70 mV.
~The images below will hopefully help. :)
*The pulley is a lever, and it helps lifts things higher with less force then trying to normally pick it up.
