Which three systems of the human body function together to move and control body parts?
(1) nervous, skeletal, and muscular
(2) muscular, endocrine, and excretory
(3) digestive, excretory, and reproductive
(4) circulatory, endocrine, and respiratory

1) Nervous, skeletal, and muscular

Explanation:

The nervous system tells your muscles to move when they need to, whether it's a conscious decision or if it's an automatic response to stimulus (ex: moving your hand off of a hot stove because it hurts). The skeletal system supports the body and joints help things like your fingers and hips move freely. The muscular system is what reinforces the support of the skeletal system and contains the nerves that receive orders from the nervous system to move. Hope this helps!

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

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.