I need some help answering a couple of questions.?

thanks alot.. whoever knows the most or has the best explainations wins best answer.











In a testcross, which of the following must be true...


a. One of the individuals is homozygous dominant.


b.One of the individuals is homozygous recessive


c. Both individuals are heterozygous


d. both individuals are homozygous


e. both individuals have an unknown phenotype.














Diatoms are the primary producers in whch of the following ecosystems...


a. Marine


b. Desert


c. Temperature broadleaf forest


d. Chaparral


e. Tropical rain forest.











During which type of reaction is energy consumed?


a. Hydrolisis


b. Catabolic


c. oxidation-reduction


d. endergonic


e. exergonic

I need some help answering a couple of questions.?
1) B one individual is homozygous recessive





This allows you to see, for example, if some recessive show up. The test cross determines if a phenotypically dominant organism has a heterzygous or homozygous genotype. If it is a homozygous genotype, all offspring are going to be phenotypically dominant. If it is heterzygous, some dominant and some recessive phentoypes appear.





2) A. Marine


Diatoms (Greek: διά (dia) = "through" + τέμνειν (temnein) = "to cut", i.e., "cut in half") are a major group of eukaryotic algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although some form chains or simple colonies. A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (hydrated silicon dioxide). These walls show a wide diversity in form, some quite beautiful and ornate, but usually consist of two asymmetrical sides with a split between them, hence the group name. Fossil evidence suggests that they originated during, or before, the early Jurassic Period. (http://en.wikipedia.org/wiki/Diatom)


The fact that they are a type of plankton shows that they are in marine ecosystems





3) D. endergonic


end·er·gon·ic (ndr-gnk) KEY





ADJECTIVE:





Requiring energy: an endergonic chemical reaction





http://education.yahoo.com/reference/dic...





It takes energy for it to occur








I am 100% on all three answers
Reply:B. A test cross is when you cross the unknown with a homozygous recessive individual. Since the known is homozygous recessive, the genotype of the unknown will show up.





A. Marine. Diatoms are unicellular algae.





D. That's the definition of endergonic reactions.