Answer:
Between one-third and one-half of all fertilized eggs never fully implant. A pregnancy is considered to be established only after implantation is complete
Answer:
Explanation:
In the structure of Nucleic acids the nucleobases (nucleotide and bases) are arranged is a specific form.This form of arrangement is called Base stacking.It simply refers to the bond formed between the adjacent bases.
These nitrogenous bases of (A,T,C.G) pairing in DNA are in planes in geometry.The bases planes stack with one another.This form of arrangement give rooms for more Van der Waals interactions in the plane of the bases.Although the Van der Waals are weak interactions,the bond ensure that these bases are braided or twisted together to give maximum energy,to maintain stability of the bases,and therefore of DNA structure
Therefore in water and other aqueous solution the stability of structure of DNA is enhanced by the base stacking,(coiling or twisting)with maximum van der waals interaction among the bases, than the hydrogen bonds formed between bases.Generally there are more stacking among G-C,than A-T,thus the former pairing contribute more the structural stability than the latter (A-T)
Answer:
Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water. (NOAA)".
Explanation:
1. During DNA elongation, polymerase enzyme adds new, free nucleotides to the three prime end of the newly forming strand, elongating it in five prime to three prime direction while the telomerase protects the important genes at the end of the chromosome from been deleted as the DNA strand shorten during DNA elongation.
2. During DNA elongation, helicase enzyme separates the double stranded DNA into single strand by melting the hydrogen bond that holds the DNA molecule together thus enabling each strand to be copied while the telomerase acts by preventing the telomere from been deleted during elongation.
<span>a. chemicals produced by neurons that function as hormones—neurohormones
b. chemicals that act locally on nearby cells—paracrine factors
c. chemicals secreted by presynaptic terminal—neurotransmiters
d. influences same cell type from which it is secreted—autocrine agent
e. chemical secreted into the blood by specialized cells; travels some distance to target tissues—endocrine hormones</span>
