Chemical energy sources are often portable and provide large amounts of energy. Fossil fuels are one kind of chemical energy source. Most of the energy we use in the United States is generated by the combustion of fossil fuels. However, fossil fuel combustion adds greenhouse gases to the atmosphere, mostly CO2. One measure of the total amount of greenhouse gases that are emitted into the atmosphere each year is called a carbon footprint. Study these images to compare the carbon footprint of an average person in the United States to an average person around the world. Knowing that greenhouse gases are contributing to climate change, how can we reduce our carbon footprint, particularly in the United States? Could hydrogen fuel replace fossil fuels in the future? Why or why not? Should the size of a person’s carbon footprint be limited by law? Why or why not?

To be or not to be that is da question

If an organ has six haploid chromosomes, how many chromosomes are present. 6 12

Mr. j, age 42, is a construction worker in las vegas. he recently noticed that a mole on his face seemed to be getting larger and darker. at first he did not worry because he was in the sun a lot and assumed the change may have been caused by sunburn. after a month, not only was the mole larger and darker, but it appeared to be “bumpy.” his doctor diagnosed a malignant melanoma skin cancer following biopsy of the nevus. mr. j reports pain in his right shin that does not go away when he puts his feet up or sleeps. discussion questions 1. relate mr. j’s skin changes to the warning signs for malignant melanoma. (see malignant melanoma.) 2. discuss the normal progression of this malignancy. what is the significance of the bone pain that mr. j is experiencing? (see malignant melanoma.) 3. discuss the treatment available for this patient and the prognosis for recovery. (see malignant melanoma.)