Edward Jenner inferred that a person who once had small pox cannot have it once again. So something is there in these persons which grows after the initial infection which interferes with the secondary infection resisting it.
<h3><u>
Explanation:</u></h3>
Edward Jenner is called the Father of Vaccination. Jenner noticed that the milkmaids who deal with the cows all the time don't generally suffer from the cowpox or small pox. Then as an Experiment, he took some sample from the pustules of the cow having pox and then cleaned it and injected the sample into a healthy child. Then when everyone of the locality suffered from the same disease, that child remained healthy. So that lead to infer that there are something in the pustule which lead to resist the secondary infection of this disease. So this lead to the invention of vaccines.
Insects become resistant to pesticides after being exposed to it for some time.
hope this helps
© 1998, 1999 Gregory Carey Chapter 7: The New Genetics - 1 Chapter 7: The New Genetics—Techniques for DNA Analysis Introduction Before the 1980s, finding the genotype of an individual usually involved various laboratory assays for a gene product—the protein or enzyme. The cases of the ABO and Rhesus blood groups are classic examples of how one infers genotypes from the reaction of gene products with certain chemicals. In the mid 1980s, genetic technology took a great leap forward with the ability to genotype the DNA itself. The geneticist could now examine the DNA directly without going through the laborious process of developing assays to detect individual differences in proteins and enzymes. Direct DNA analysis had the further advantage of being able to identify alleles in sections of DNA that did not code for polypeptide chains. As a result of these new advances, the number of genetic loci that could be detected increased exponentially and soon led to the identification of the genes for disorders that had remained a mystery for the better part of this century. In this chapter, the major molecular techniques are outlined. The purpose is to provide a quick and understandable reference for the social scientist. The content of this chapter is not something that is required to understand genetics, what genes are, or how they relate to human behavior. Indeed, this chapter may be skipped without any great loss of continuity. Hence, only the essentials are given and the reader interested in the laboratory science behind the techniques is referred to contemporary textbooks on molecular genetics. We begin by defining a series of basic tools and techniques. © 1998, 1999 Gregory Carey Chapter 7: The New Genetics - 2 Basic Tools and Techniques: Basic tools: Electrophoresis Electrophoresis is a technique that separates small biological molecules by their molecular weight. It may be applied to molecules as large as proteins and enzymes as well as to small snippets of DNA and RNA. One begins the procedure by constructing a “gel”—a highly viscous material the actual chemistry of which need not concern us. Purified copies of the biological specimen are then injected into a “starting lane” at one end of the gel. Finally, a weak electric current is passed through the gel for a specified amount of time. Gravity and the electric current cause the biological molecules to migrate to the opposite end of the gel. The extent to which any molecule moves depends upon its electrical charge, molecular weight, the viscosity of the gel, the strength of the current, and the amA. The simplest method to denature DNA is to h33///////////////////////(http://psych.colorado.edu/~carey/hgss/hgsschapters/HGSS_Chapter07.pdf) # cited
Seismic waves are waves produced by earthquakes. This occurs
when rocks under the earth suddenly break or explode. There are two MAIN TYPES
of seismic waves called body waves and surface waves.
<span>Body waves have the capacity to travel through the Earth's
inner layers. They have a higher frequency and they are the ones that first
occur under water at the onset of an earthquake. They can be subdivided
into two types, the primary and secondary waves that arrive at seismic records
one after another.
Surface waves can only traverse through the surface of the planet like ripples
in the water. These waves can easily be detected on a seismogram result. These
waves arrive after body waves and they are the ones mostly responsible for
damages and destruction bought by earthquakes.</span>
<span> </span>
