Besides a high voltage shock, what is another method to make e. coli competent to take up "naked" dna?
a. high concentrations of calcium ions followed by high temperature
b. high concentrations of calcium ions and several hours on ice
c. large amounts of dna added directly to a bacterial culture growing at 37c
d. high concentrations of minerals followed by high temperature
e. a high voltage shock is the only way to make e. coli competent

Bisphenol a (often called bpa) is a chemical found in products that people use every day, from water bottles to food containers to children's toys. unfortunately, bpa leaches out of its many products and makes its way into our bodies. what are the health effects of bpa exposure? ongoing research is finding that elevated exposure to bpa can affect a wide variety of developmental and physiological processes, but one of the first studies of bpa's health effects came about because of a simple mistake in the lab. at a laboratory at case western reserve university in 1998, geneticist patricia hunt was making a routine check of her female lab mice. as she extracted and examined developing eggs from the ovaries, she began to wonder what had gone wrong. she noticed that many of the eggs showed problems with their chromosomes, and some had irregular amounts of genetic material, which can lead to miscarriages and birth defects in mammals. she learned that a lab assistant had mistakenly washed the plastic mouse cages and water bottles with a harsh soap, releasing bpa from the plastic. knowing that bpa is an endocrine disruptor, a chemical that can enter organisms and mimic hormones, hunt set out to discover whether it had adversely affected her mice.

Environmental science are unconsidered with methods to preserve natural resourcesa. trueb. false

Which structure in the cardiovascular system connect arteries to veins?