An earthworm has a complete digestive system. How does the earthworm remove undigested food?

Your brain and neurons are in constant action, sending billions of ___________and________messages each day to keep everything, f

Leviafan [203]

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.

if wrong report me

5 0

3 years ago

Which of the following bacteria can grow in low oxygen environment: Salmonella Yersinia Listria monocytogenes Clostridium botuli

AlexFokin [52]

Answer: Clostridium botulinium

Explanation:

An anaerobic bacteria is an organism which does not require oxygen for it's survival. It may not survive or die in the presence of oxygen. These bacteria are used for the process of fermentation for the preparation of beverage and dairy products.

Clostridium botulinium is the example of the anaerobic bacteria. It is found in soil or marine environment in the form of spores. This bacteria is rod shaped. It forms the spores when the conditions for survival is poor. It causes a disease called as botulism.

6 0

3 years ago

Scientists originally thought cell membranes evolved before RNA. However, recent evidence suggests RNA developed before the memb

Darya [45]

Answer:

The need for replication, specialization, compartmentalization is key to understand that RNA evolved first

Explanation:

Logical contrast considering a certain catalytic activities of cardinal importance in the early evolution of life ;

• using an RNA molecule that is involved in to catalyzing the process of templated polymerization –selecting a random RNA molecule as a template.

• the ribozyme activity in this process must have engaged an in vitro process in a body part that no longer has a function such that it that can only synthesize moderate lengths of RNA

• when this molecules acts on the copies of itself can replicate

• when it acts on copies of other type of RNA molecules in its surrounding he can promote their replication

• a cooperative system might have evolved from the neighbors to help the survival of this friendly RNA molecules – through catalytic actions, such that a set of different types of RNA molecules evolves with a mark of specialization for different activity.

The development of individual compartments is proposed to be akin to the effective self-replicating systems.

• If RNA molecules are mutually beneficial they may serve the purposes of being specialized for templated polymerization.

• If these RNAs were free to diffuse among a large population of other RNA molecules, they could be assimilated into an established group by other replicating systems, which in turn may compete with the original RNA system for raw materials.

• The quality of the self-replicating systems they generated relies on the compartment that restricts the RNA molecules only to the system they serve.

• compartments started simply and perhaps had simple adsorption on surfaces or simple particles.

• compartmentalization became complex requiring a class of small molecules with varying physicochemical properties liike being amphipathic.

• This gave rise to the phospholipids mainly and the present-day cells often are coated by a plasma membrane consisting of amphipathic molecules in this configuration.

3 0

3 years ago

Which of these is the correct sequence of events leading to evolution?

Nat2105 [25]

The last one is correct

5 0

3 years ago

Read 2 more answers

If there are no differences between the amino acid sequences in the cytochrome c protein of humans and chimpanzees, why aren't w

JulsSmile [24]

The two factors that determine the shape of a protein 
1. Primary structure. The sequence of amino acids. Amino acids are the building blocks of protein. It is a strong of linearity that can be thousands in length. Moreover, the formation of the amino acid and its system is influenced by its genes’ nucleotides arrangement. 
2. Hence the next factor is how is the structure of the amino acids bended and folded with itself that forms the certain protein molecule and forms the larger complex structure

4 0

3 years ago