Which of the following occurs during mitosis but not during meiosis 1?
A) the chromosomes are pulled to opposite poles of the spindle apparatus
B) the chromatids of each chromosome are separated
C) the nuclear envelope breaks down
D) both synapsis and crossing over take place
E) the diploid number of chromosomes is reduced to the haploid number

List the advantages and disadavantages of the switch from persistent chlorinated hydrocarbon pesticides (such as ddt) to nonpersistent organophosphate pesicides. have the benefits of the switch outweighed the disadvantages? explain.

Imagine you are introducing the lac operan and the trp operon to students who have never learned about it before. complete the table to compare the similarities and differences between the two operons

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.)