When is light penetration in a river or stream likely to be lowest

a. the source
b. the mouth
c. the middle portion
d. none of the above

Drag each label to the correct location on the image. each label can be used more than once. a scientist introduced mutations in a gene sequence isolated from bacteria. study the sequence, and identify the steps where the mutations may affect the formation of proteins. in the sequence, black letters stand for protein coding regions and red letters stand for noncoding regions. protein will not be changed. protein may be changed. attcgtgttc atcgtgttc atcgtattc attcgtattc

Which of the following produces carbon dioxide? a. plants b. animals c. decomposers d. all of the above

What factors contribute to the effect an environmental toxin has on the human body?