B. Natural selection
Natural selection is the most important force of evolution. Other forces of evolution are mutation, gene flow and genetic drift.
The beginning of the Cambrian Period is marked by the evolution of hard body parts such as calcium carbonate shells. ... These body parts fossilize more easily than soft tissues, and thus the fossil record becomes much more complete after their appearance.
Answer:
C. Promoter; Operator
Explanation:
Related genes in bacteria are often found in a cluster on the chromosome, where they are transcribed from one RNA polymerase binding site(promoter) as a single unit while other regulatory proteins are binding repressors attached to DNA pieces known as operators. When they are bound to operator, a repressor reduces transcription.
Genes in cases like this encode proteins, having various roles which include fuel metabolism, maintenance of cell structure, and
also defense against viruses in its process. A great number of these proteins are been used while others are needed only under certain decrees. Therefore, it is said that cells don't express all the genes in their genome always.
Answer:
The North produced 17 times more cotton and woolen textiles than the South, 30 times more leather goods, 20 times more pig iron, and 32 times more firearms. The North produced 3,200 firearms to every 100 produced in the South.
Explanation:
Answer:
In order for this gas transfer to take place, an amphibian’s skin is damp and often slimy. Although cutaneous respiration requires less energy than breathing via lungs or gills, it can only take place at a constant rate. Most amphibians have lungs to handle respiration at a greater rate when required.
Explanation:
