The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
Answer:
A.) Pollen are well preserved in the sediment layers because they are highly resistant to decay.
B.) Other indicators that can be used to determine past climates are through the analysis of the width of tree rings and the coral reefs formed underwater.
Answer:
2) CAG - TTC - ACG mutates to CAG - TTC - ACC - ACG
Explanation:
Insertions are mutations in which extra base pairs are inserted into a new place in the DNA. The number of base pairs inserted can range from one to thousands!
In option no. 1: We see that there is not addition of a single or more than one base, but the new base sequence is different from the original sequence at three places i.e: TTA - CAC - G
In option no. 2: The insertion of three bases ACC has been made exactly after TTC, the whole sequence and arrangement of bases remain same except this insertion.
In option no. 3: The first base of the sequence T is replaced with A, and all other sequence is same. This type of mutation is called substitution in which one base is replaced by other.
In option no. 4: The last base of the sequence C is deleted, and is not present in new sequence. This type of mutation is called deletion in which a base is removed from the sequence.
Conclusion: Therefore, the best option is 2, in which whole codon is inserted in the DNA base sequence.
<span>your answer ..is sea lilies </span>
