Answer:
mutation rates can be used to design molecular clocks in order to estimate divergence times among species
Explanation:
In evolutionary biology, the substitution rates (also known as mutation rates) are used for the development of 'molecular clocks' which allow estimating the divergence times among species or among taxonomic groups. Molecular clocks can be designed by estimating the divergence rate of nucleotide sequences (either DNA or RNA) and amino acid (protein) sequences. These substitution rates can also be used to track how quickly viruses evolve (for example, in a pandemic situation).
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.
Answer:
Both have two circuits for circulation.
Explanation:
- The two circuits of circulations are known as the systemic circuit and the pulmonary circuit.
- In the<u> systemic circuit</u> oxygenated blood from the heart is pumped to all parts of the body through the blood vessels and then the blood is pumped back to he heart.
- In the<u> pulmonary circuit</u> deoxygenated blood from all parts of the body is pumped from the heart to the lungs to be oxygenated and after it is oxygenated it is pumped back to the heart.
