12. Scientists found that, over a period of 200 years, a mountain pond was 2 points transformed into a meadow. During that time, several communities of
organisms were replaced by different communities. Which of these best
explains why new communities were able to replace older communities.
The original species became extinct
Species in the older community died from old age
The abiotic characteristics of the habitat changed
Diseases that killed the older organisms disappeared
Clear selection

answer; /// i believe the correct answer is (thrombocytopenia); (a)

i am going to guess that it is co2.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.