Answer:
b. di uses across a synaptic cleft from a neuron to a muscle cell.
Explanation:
A neurotransmitter is di uses across a synaptic cleft from a neuron to a muscle cell. Neurotransmitters are chemicals which enable neurotransmission. In reaction to an impulse a motor neuron axon secretes a neurotransmitter and causes the muscle fiber to contract. It is a chemical messenger which passes on the signals across the chemical synapse.
Example of selective breeding: Cows that produce lots of milk. Selective breeding to create more useful varieties of animals and plants is a form of biotechnology that human beings have used for thousands of years. Biotechnology includes any use of science or technology to alter the characteristics of a particular breed or animal.
The biome that has infertile soil, principally oxisols, to which the vegetation <span>has roots systems that capture nutrients from litter decay, is the tropical rainforest.
Soil types are highly variable in the tropics and are the result of a combination of several elements or variables which includes climate, vegetation, topographic position, parent material and also the soil age. Most of the tropical soils are described by leaching and poor nutrients. It also has two classifications: namely the ultisols and oxisols. Ultisols are known as well-weathered, acidic red clays soils. They are deficient primarily in major nutrients such as potassium and calcium. Oxisols are also an acidic type of tropical soil. However, they are well drained compared to the ultisols.
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Human Immunodeficiency Virus -- this is HIV, the virus that causes AIDS.
Flu viruses. There are lots of different strains of flu virus, which is why new vaccines have to be made every year.
Cold virus. The common cold is caused by a virus.
Tumor suppressor genes and proto-oncogenes cause cancer cells to divide uncontrollably.
The answer is B) proto-oncogenes.
