Answer and Explanation:
In the DNA molecule, that is formed by two strands of nucleotides, makes sense that each nucleotide is strongly bond to one another while the strands have weaker bonds, for one particular reason.
The double-stranded nature of the DNA is a key element in its correct functioning. When the DNA needs to be "unzipped" for certain processes such as replication and transcription, the weak hydrogen bonds that connect the two strands are broken. If the bonds between the strands were stronger, much more energy would be needed to perform the processes mentioned before, and that wouldn't be beneficial for the cells.
B. a mutation in the whales' DNA caused the formation of a useless skeletal structure.
C. the whales may acquire the ability to live on land before the end of their lifetime.
D. the hip bone may have played an important role in the whales' ancestors locomotion.
The correct answer is D. The hip bone may have played an important role in the whales' ancestors locomotion.
Explanation:
Vestigial structures such as the vestigial hip bone in whales refer to structures or features that do not have a function or purpose and therefore are classified as vestigial. In most cases, these structures had an important function in the past but due to evolution and changes in the species, they stop being functional. This means even though the vestigial hip bone of whales does not represent a function nowadays it may have played an important role or function for the ancestors of this species (option D).
When a pregnant woman is in labor, the body sends hormones that increase the intensity of contractions, which then increases the secretion of the same hormones.
When blood sugar is too low, the body sends hormones that raise blood sugar until it reaches a typical level and hormone secretion slows.
When a person is jogging, the body sends hormones that continually decrease the rate of oxygen supply to the legs
Answer:
The statement - When blood sugar is too low, the body sends hormones that raise blood sugar until it reaches a typical level and hormone secretion slows, describes a negative feedback loop.
Explanation:
In the human body, the term homeostasis means the tendency of the various systems in the human body to stay in optimal ranges for health by self regulation through feedback controls. It is very important because it maintains equilibrium and provides stability to the human body. A negative feedback loop (inhibitory loop) is a type of self-regulating system in which increased output from the system inhibits the future production by the system. Example of negative feedback to achieve homeostasis are blood pressure, body temperature, blood sugar. In blood sugar regulation, the hormone insulin lowers blood glucose when levels are high and the glucagon increases blood glucose when levels are low. In a positive feedback system, the output amplifies the original stimulus. Examples of a positive feedback system are child birth, lactation, blood clotting etc. During child birth, the hormone oxytocin released increases and speeds up the contractions.