Answer:
It's similar to the nervous system in that it plays a vital role in controlling and regulating many of the body's functions. However, while the nervous system uses nerve impulses and neurotransmitters for communication, the endocrine system uses chemical messengers called hormones.
D
Explanation:
Flowing water has intrinsic kinetic energy that is harnessed to rotate the turbine. The turbine rotates hence gains mechanical energy because it is doing work. This work is used to rotate a dynamo of a generator which generates electricity. The mechanical energy is thus converted into electric energy by the dynamo. The electric energy is then carried by the power lines to the users.
The answer is 3- water molecules in the atmosphere speed up and fall
Answer:
The answer is B. Some organic molecules, including amino acids, could have been produced from chemical reactions on early Earth.
Explanation:
Miller-Urey Experiment:
The Miller-Urey experiment was an attempt to explain the origin of life on Earth. Miller-Urey simulated the primordial soup i.e. the environment of primitive Earth to prove the spontaneous generation of organic molecules. The conditions they introduced included:
- A methane-ammonia-hydrogen and water mixture that exactly simulated the primordial soup.
- A spark of 70,000 volts that simulated lightening.
- A temperature of 800 degree Celsius.
Observations:
- After running for 18 days, the final solution was examined for presence of organic molecules.
- Miller-Urey observed that most of the methane and ammonia had been consumed and the mixture contained carbon monoxide and nitrogen.
- The solution further contained 25 amino acids (mainly, glycine, alanine and aspartic acid)
, several fatty acids
, hydroxy acids and amide products.
The experiment concluded that simple organic compounds such as amino acids could have been formed through spontaneous generation under the Earth's primitive environmental conditions.
Answer: If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will D. complete the cycle and divide. G1 checkpoint occurs between the G1 and S phase of the cell cycle. When the cell is grown sufficiently and produces all components of DNA replication it enters in the S phase.