There are 4 nitrogenous bases in DNA. Adenine pairs with thymine, and Guanine pairs with cytosine. A Dna Nucleotide consists of a 5 carbon sugar, a phosphate group and a nitrogenous base. These bases are paired up by weak hydrogen bonds, so when they have have to replicate, the enzyme helicase can easily unzip the Dna. <span />
The answer is A, Viruses
Viruses cannot reproduce on their own , so they have to inject their DNA or RNA into the nucleuus of a cell. By doing this, the virus will take over that cells and within times, that cells will pop up and producing more viruses.
This reproduced virus will repeat the same process until our immune systems stop them
Asthma is a chronic disease of the lung that has been increasing at an alarming rate in industrialized countries around the world over the last few decades. Although considerable progress has been made in our understanding of the underlying pathogenesis of the disease, the exact causes of the increasing prevalence are unknown. Studies suggest that most asthma develops in early childhood and that environmental factors present early in life may be crucial in the development of disease. One potential explanation for the recent epidemic referred to as the "hygiene hypothesis" postulates that factors that have resulted in a reduction in exposure to microbial products and/or infections in the western world may be contributing to this rise in disease prevalence. As early life influences are known to play an important role in establishment of asthma, studies have focused on the interface between mother and child that occurs during gestation and through breastfeeding. In this regard, the body of evidence regarding the relationship between breastfeeding and asthma indicates benefit but with the potential for risk. While providing population-level protection from infections and atopy in infancy and early childhood, breastfeeding might also pose an increased risk of atopic asthma among children with asthmatic mothers.
