The medulla oblongata detects the levels of oxygen and carbon dioxide concentrations and signals the muscles in the heart, the lungs and diaphragm to increase or decrease thebreathing. The pons controls the speed of inhalation and exhalation orrespiration rate depending on the need of the body.
Answer:
B. Dominant for one trait and recessive for the other
Explanation:
using the Punnetts square for the question above, the 9 in the ration refers to a dominant for both traits such as AABB, AaBb.
while the 3: 3 refers to a dominant for a single trait and recessive for one such as AAbb, Aabb, aaBB, aaBb
and the 1 refers to recessive for both traits such as aabb.
The genotypes of the parents are Aa (heterozygous) and aa (recessive homozygous).
For example:
If the purple flower is dominant phenotype, then A is a dominant allele for it and Aa is a genotype which will give the purple colour.
In this case, white flower is recessive phenotype with aa genotype.
If we cross Aa x aa
<span>The offspring is going to be Aa Aa aa aa (half purple and half white)</span>
Answer:
Until recently, most neuroscientists thought we were born with all the neurons we were ever going to have. As children we might produce some new neurons to help build the pathways - called neural circuits - that act as information highways between different areas of the brain. But scientists believed that once a neural circuit was in place, adding any new neurons would disrupt the flow of information and disable the brain’s communication system.
In 1962, scientist Joseph Altman challenged this belief when he saw evidence of neurogenesis (the birth of neurons) in a region of the adult rat brain called the hippocampus. He later reported that newborn neurons migrated from their birthplace in the hippocampus to other parts of the brain. In 1979, another scientist, Michael Kaplan, confirmed Altman’s findings in the rat brain, and in 1983 he found neural precursor cells in the forebrain of an adult monkey.
These discoveries about neurogenesis in the adult brain were surprising to other researchers who didn’t think they could be true in humans. But in the early 1980s, a scientist trying to understand how birds learn to sing suggested that neuroscientists look again at neurogenesis in the adult brain and begin to see how it might make sense. In a series of experiments, Fernando Nottebohm and his research team showed that the numbers of neurons in the forebrains of male canaries dramatically increased during the mating season. This was the same time in which the birds had to learn new songs to attract females.
Why did these bird brains add neurons at such a critical time in learning? Nottebohm believed it was because fresh neurons helped store new song patterns within the neural circuits of the forebrain, the area of the brain that controls complex behaviors. These new neurons made learning possible. If birds made new neurons to help them remember and learn, Nottebohm thought the brains of mammals might too.
Other scientists believed these findings could not apply to mammals, but Elizabeth Gould later found evidence of newborn neurons in a distinct area of the brain in monkeys, and Fred Gage and Peter Eriksson showed that the adult human brain produced new neurons in a similar area.
For some neuroscientists, neurogenesis in the adult brain is still an unproven theory. But others think the evidence offers intriguing possibilities about the role of adult-generated neurons in learning and memory.
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DNA, cell membrane, cytoplasm, and ribosomes.
Both prokaryotic and eukaryotic cells have structures in common. All cells have a cell membrane, ribosomes, cytoplasm, and DNA. The cell membrane, or plasma membrane, is the phospholipid layer that surrounds the cell and protects it from the outside environment.
