Sickle cell anemia is a disease that affects the shape of red blood cells in individuals who have two copies of the sickle cell allele. Individuals with one copy, called carriers, do not exhibit sickle cell anemia but are resistant to the disease malaria, which is spread by mosquitoes. The top map shows where malaria is common, while the bottom map shows regions where the sickle cell allele is most prevalent. Which of the following statements might account for the prevalence of the sickle cell allele in the areas shown?
a
Sickle cell is a polygenic trait, so it must be present on many chromosomes.
b
The allele is advantageous in cold areas uninhabited by mosquitoes.
c
Sickle cell is caused by chromosomal nondisjunction.
d
The allele is advantageous in tropical areas where the risk of malaria is the greatest.

Recombinant dna (rdna) creates offspring which are genetically identical to the parent is the process of breeding only organisms with desirable traits involves the removal of the nucleus of a cell combines genes from organisms of different species in a lab

Which two criteria must be met before scientist can use radiocarbon dating? explain your answer

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.)