Answer:
who was the first scientist to discover a cell when observing a tin section of deed cork under a crude compound microscope?
Robert Hooke!
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Answer:
they are Na+, K+ and Ca2+ ion channels.
Explanation:
Ionotropic acetylcholine receptors are also called nicotinic acetylcholine receptors because beside acetylcholine (Ch) they respond to nicotine. These receptors are primary receptors in muscle for motor nerve-muscle communication that controls muscle contraction.
Two molecules of ACh are required for receptor to open. Since the receptors are linked to ion channels, the channels open. Opening of the channel allows positively charged ions to move across it: sodium enters the cell and potassium exits.
Living things cannot live without eachother due to the food chain, if an animal loses it's food so will his predator and so on. Soon they will end up extinct, this is why it's important to take care of animals.
Answer:
The correct option is A. Steroid hormones exert their action by entering the nucleus of a cell and initiating or altering the expression of a gene.
Explanation:
Steroid hormones are derived from cholesterol and regulate multiple biological processes. All steroid hormones exert their action by crossing the plasma membrane and by binding with their respective intracellular receptors. They stimulate cell growth in a very different way, their lipophilic nature gives them the ability to cross lipid barriers, so, without the need for extracellular signals, these hormones can easily enter the cell, cross the cytoplasm and reach the nucleus. There they bind to specific receptors that are associated with DNA promoter regions, modifying their structure and promoting the expression of the genes under their control.
