John Needham performed a series of experiments based on Redi's experiment to support the theory of spontaneous generation. In his experiment, Needham boiled different kinds of broth in flasks, sealed them, and then let the broth cool. Microorganisms developed in the broth, providing Needham with evidence of spontaneous generation. Even though Needham's results supported the theory, what criticism did other scientists have about the experiment? A. The experiments were conducted only once.
B. Sterile flasks should have been used in the experiments.
C. The broth was contaminated before the flasks were sealed.
D. A greater variety of broth should have been tested.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.

hi~~

i would say that hybridization occurs frequently in nature, because there are many types of hybrids that have occurred naturally, such as the mule (male donkey + female horse)

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

the tricuspid valve is present between right atrium and right ventricle