<span>The geologic time scale is divided into periods, which are then divided into epochs, which are further divided into ages. For example, the time of the dinosaurs lasted 3 periods (Triassic, Jurassic, Cretaceous), each period had 3 epochs (late, early, middle), and each age fit into one of those. Many epochs have more than 1 age associated with them.
As for the basis for differentiating the eras, I'm not so sure. The only one I can say for sure is the end of the Cretaceous, which is when the dinosaurs suddenly became extinct due to a meteor impact. I think the divisions are based on significant, global-scale events that changed the world.
Sorry its so long but that the answer i think >:) ur welcome
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The medulla has the ascending and the descending tract which function to link the brain with the spinal cord.
<h3>What is the role of medulla?</h3>
- Medulla oblongata is the lowermost part of the brain.
- It is located at the place where the brain and the spinal cord connect thus it carries nerve signals between the brain to spinal cord thus help the entire body to communicate.
- It controls biological processes like blood pressure, breathing and heartbeat.
- Ascending tract functions to carry sensory information from the body (e.g.: pain) from the spinal cord to the brain (upwards).
- Descending tract carry motor information (e.g.: instructions to move the arm) from the brain down the spinal cord to the body (downward).
- Damage to medulla can lead to respiratory failure, paralysis, or loss of sensation.
Learn more about medulla here:
brainly.com/question/26723889
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Answer:
<u>Passive transport</u>: It does not need any energy to occur. Happens in favor of an electrochemical gradient. Simple diffusion and facilitated diffusion are kinds of passive transport.
<u>Simple diffusion</u>: molecules freely moves through the membrane.
<u>Facilitated diffusion</u>: molecules are carried through the membrane by channel proteins or carrier proteins.
<u>Active transport</u> needs energy, which can be taken from the ATP molecule (<u>Primary active transport</u>) or from a membrane electrical potential (<u>Secondary active transport</u>).
Explanation:
- <u>Diffusion</u>: This is a pathway for some <em>small polar hydrophilic molecules</em> that can<em> freely move through the membrane</em>. Membrane´s permeability <em>depends</em> on the <em>size of the molecule</em>, the bigger the molecule is, the less capacity to cross the membrane it has. Diffusion is a very slow process and to be efficient requires short distances and <em>pronounced concentration gradients</em>. An example of diffusion is <em>osmosis</em> where water is the transported molecule.
- <u>Facilitated diffusion</u>: Refers to the transport of <em>hydrophilic molecules</em> that <em>are not able to freely cross the membrane</em>. <em>Channel protein</em> and many <em>carrier proteins</em> are in charge of this <em>passive transport</em>. If uncharged molecules need to be carried this process depends on <em>concentration gradients</em> and molecules are transported from a higher concentration side to a lower concentration side. If ions need to be transported this process depends on an <em>electrochemical gradient</em>. The <em>glucose</em> is an example of a hydrophilic protein that gets into the cell by facilitated diffusion.
<em>Simple diffusion</em> and <em>facilitated diffusion</em> are <u>passive transport</u> processes because the cell <u><em>does not need any energy</em></u> to make it happen.
- <u>Active transport</u> occurs <em>against the electrochemical gradient</em>, so <u><em>it does need energy to happen</em></u>. Molecules go from a high concentration side to a lower concentration side. This process is always in charge of <em>carrier proteins</em>. In <u>primary active transport</u> the <em>energy</em> needed <em>comes from</em> the <em>ATP</em> molecule. An example of primary active transport is the <em>Na-K bomb</em>. In <u>secondary active transport</u>, the<em> energy comes from</em> the <em>membrane electric potential</em>. Examples of secondary active transport are the carriage of <em>Na, K, Mg metallic ions</em>.
I believe that 2 is correct. :)