ANSWER:
Most types of cancer are believed to begin with a random genetic mutation. This is followed by mutations, which endow the cancer cells with properties allowing them to grow without normal controls to become a tumor.
Mutation is any change in the DNA sequence of a cell. Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment.
Genetic Mutations that lead to cancer cell formation can occur in two forms:
1. GROWTH-PROMOTING GENES are commonly mutated in cancer cells, becoming SUPER-ACTIVE and producing cells that are too strongly stimulated by growth receptors.
2. Mutations can INACTIVATE the genes that suppress cell proliferation or those that signal the need for apoptosis. These genes are known as TUMOR SUPPRESSOR GENES.
<span>The characteristics that scientists used to classify living organisms into six kingdoms include the following:
1. Cell type: living organisms are classified into prokaryotes and eukaryotes based on the presence of nucleus and distinct arrangement of the organelles in their cells.
2. Mobility: living organisms are categorized into kingdoms based on their ability or inability to move about.
3. Cell structure: the cells structure was used to divide living organisms into plants and animals. Those living organisms that have cell wall are classified as plants while those who do not have cell wall are classified as animals.
4. Number of cells: living organisms that are made up of only one cell are classified as unicellular while those with many cells are termed multi cellular.
5. Reproduction method: living organisms are classified based on whether they reproduce sexually or asexually.
6. Manner of obtaining energy: living organisms that can prouduce their own food are called autotrophs while those that can not produce their own foood are termed heterotrophs. Plants are essentially categorised as autotrophs while animals are described as heterotrophs.</span>
Inclined plane allows the same work to be done with a smaller force exerted over a greater distance.
John Dalton's theory:
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) Compounds are formed by a combination of two or more different kinds of atoms.
The half-life of Carbon-14 is 5760 years.
<span>For carbon-14 to have decayed down by a factor of 12, we know between 3 and 4 half-lives must have elapsed. Since 4 half-lives is only 23,000 years, the sample is considerably younger than a dinosaur bone. (Unless we assume it's been contaminated with modern carbon, in which case, any age calculation based on carbon-14 is worthless.) </span>
<span>The decay equation is y = ae^(-0.0856t) with t in days. </span>
<span>To find the half-life, we solve for t such that y/a = 0.5. </span>
<span>0.5 = e^(-0.0856t) </span>
<span>Take natural logs of both sides: </span>
<span>-ln(2) = -0.0856t </span>
<span>-0.6931 = -0.0856t </span>
<span>Divide both sides by -0.0856... </span>
<span>8.096 = t </span>
<span>The half-life is 8.096 days.</span>
