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.
The correct answer is mRNA.
mRNA or messenger RNA is synthesized during the process of transcription, from DNA molecule which is used as a template. mRNA contains information about protein synthesis (translation) in the form of nucleotide triplets or codons.
In the example above: reference book is DNA molecule (template for copies), copies are mRNA, wood is amino acids (building blocks) and doghouse is protein.
The cross between Dd egg-snail and a dd s snail mate will result in snails with genotype 1/2 Dd:1/2 dd and phenotype all right-coiling.
<h3>What is a genotype?</h3>
The genotype refers to the allele combinations that can be found for one or more loci in an individual.
The phenotype refers to how the genes and alleles interact to produce a physical trait in an organism.
In this case, one parent can produce two types of gametes (D and d), whereas the other parent can only produce d gametes.
Learn more about genotypes here:
brainly.com/question/22117
Ionic bonds <span>are the type of bonds where there is </span>transfer<span> of electrons from one atom to another. The electrons are removed and from one atom and attached to another. A good example is salt which is composed of sodium and chlorine. Sodium readily loses one of its electrons and chlorine readily accepts it. Before losing the electron, sodium has a positive charge, but then becomes negatively charged after giving up the electron. Chlorine has a positive charge before gaining the electron but becomes negatively charged after gaining the electron. These opposite charges between sodium and chlorine attract the two elements together to form the ionic bond.</span>
