Answer:
3.5 billion years ago, or in the Eoarchean Era.
Explanation:
The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era.
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The molecule that does not enter the cell via facilitated diffusion is :
( A ) Fats
<h3>Facilitated diffusion</h3>
Facilitated diffusion is a type of spontaneous transport system ( passive ) in which charged and polar molecules such as carbohydrates, Amino acids, Nucleotides and ions move across a biological membrane. with the aid of a specific transmembrane integral proteins while
Fats ( fatty acid ) enters the enterocyte through simple diffusion process via the plasma membrane.
Hence we can conclude that The molecule that does not enter the cell via facilitated diffusion is Fats.
Learn more about Facilitated diffusion : brainly.com/question/13846065
Answer:
The capillary membranes that filter substances moving between the cerebral blood vessels and the brain are called the blood-brain barrier.
Explanation:
Capillaries are the smallest type of blood vessel in the body. Capillaries enable the exchange of substances between the blood and surrounding tissues. They are thinner than arteries and veins, because their walls are made up of only a single layer of endothelial cells, the flat cells that line all blood vessels. Capillaries function to deliver nutrients and oxygen to tissues and remove the byproducts of cellular reactions, such as water and carbon dioxide.
The Blood-brain barrier is an anatomic and biochemical barrier that protects the brain from potentially harmful substances. It is a highly selective membrane barrier at the brain microvessel level which aids transport between the systemic circulation and the central nervous system.
The Blood–brain barrier restricts the passage of pathogens, aids in ensuring solutes are diffused in the blood, and hydrophilic or large molecules into the cerebrospinal fluid, while allowing the diffusion of hydrophobic molecules (oxygen, carbondioxide, hormones) and small polar molecules.
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Start by presenting yourself, your name, where you from, etc. Then you can explain why is it important to complete all your assignments and study to get good grades... You can also talk about how High School will reflect in your future and applications for colleges. In your story write how important is to always pay attention in class and listen to your teacher.
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