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IB Biology videos / A1.1.5 Solvent properties of water as a medium for metabolism and transport Free video lesson IB · Biology
Biology A1.1.5 Learn Biology A1.1.5 in this free IB Biology video lesson for A1.1.5 Solvent properties of water as a medium for metabolism and transport .
About this video Learn Biology A1.1.5 in this free IB Biology video lesson for A1.1.5 Solvent properties of water as a medium for metabolism and transport .
The video discusses the properties of water as a solvent, emphasizing its role in metabolism and transport in both plants and animals. Water is described as a polar molecule , which allows it to effectively dissolve hydrophilic (polar) substances through interactions that involve hydrogen bonds .
Key points include:
Water's ability to dissolve a wide range of substances is crucial for the transport of nutrients , gases, and waste products in biological systems.
The dissolution process involves water molecules surrounding ions or polar compounds, stabilizing them in solution and preventing re-association.
Water's solvent properties are essential for chemical reactions in cells and for maintaining homeostasis by regulating solute concentrations.
Overall, the unique characteristics of water make it indispensable for life processes.
Video transcript 00:00 Hello guys, this is Hannah
00:01 from revision dojo and today
00:03 we're going to be looking
00:04 at a 1 .1 .5.
00:06 Solve and properties of water
00:08
linked to its roles as
00:09 a medium for metabolism and
00:11 for transport and plants and
00:12 animals. Okay, so let's look
00:14 at what a solvent is.
00:16 Now a solvent is essentially
00:17 a liquid that some form
00:19 of substance can dissolve in.
00:22 There are many different types
00:24 of solvent, but there is
00:25 no one universal solvent.
00:28 Now today we're going to
00:28 be looking at water as
00:30 a solvent. So water is
00:32 great for hydrophilic polar substances.
00:36 So as we've looked in
00:37 previous illness points, water is
00:39 a polar substance, which means
00:41 that there is an unequal
00:42 sharing of electrons between a
00:44 water molecule. So water is
00:46 also hydrophilic, which means that
00:48 it loves water. Hydro means
00:50 water. Philic means loving. So
00:52 think about that as loving
00:53 water. Now as a polar
00:56 It means that it has
00:58 a partial positive charge on
00:59 one end and a partial
01:01 negative charge on the other
01:03 end. Now let me draw
01:04 you guys a water molecule.
01:07 So imagine that this is
01:09 our hydrogen and this is
01:11 our oxygen. So we're going
01:15 to have a partial positive
01:17 charge on the hydrogen atom
01:20 and a partial negative charge
01:24 That means that there is
01:25 an unequal and unfair sharing
01:27 of electrons between these atoms.
01:30 Now also because of the
01:31 polarity, water farms hydrogen bonds
01:33 with other water molecules and
01:36 not only other one molecules
01:37 but other polar molecules.
01:52 And so when watering counters
01:56 a substance, the positive side
01:58 of water molecules is attracted
01:59 to the negative charges. And
02:02 vice versa, the negative charges
02:04 are attracted to the positive
02:05 charges of another molecule. Now,
02:08 let's also look at non
02:10 -polar molecules. So, what are
02:12 it will not dissolve in
02:14 non -polar substances as well?
02:16 As non -polar molecules, they
02:18 don't have the charged regions
02:20 cannot form hydrogen bonds with
02:22 water. Instead, what happens is
02:24 they tend to group together,
02:27 minimizing their contact with water
02:28 and expenditure, energy expenditure. So
02:31 water, it can dissolve in
02:34 non -polar substances, but it
02:35 does not do this well.
02:36 And it definitely does not
02:38 do this with the aid
02:39 of hydrogen bonds, which we
02:40 do see with polar molecules.
02:43 Okay. So hydrophobic molecules, they
02:46 need to be transported in
02:48 environment in something known as
02:50 micelles. Now micelles are these
02:53 small little vesicles that can
02:55 aid the transportation of hydrophobic
02:58 molecules in water. Now it
03:01 can either be micelles or
03:02 with some associated protein such
03:05 as oxygen being transported with
03:07 hemoglobin. So hydrophobic substances
03:16 requires some form of medium
03:24 to be transported in water
03:44 And we have said that
03:47 this could be in the
03:48 form of my cells, or
03:53 form of an associated protein,
03:57 which will help aid the
04:01 transportation process. And an example
04:03 that we have looked at
04:04 is oxygen with hemoglobin. Okay.
04:15 nice to remember that the
04:16 solubility of oxygen is greater
04:18 at higher temperatures. Keep this
04:20 syllabus points ahead. Now, let's
04:23 look at the dissolution process.
04:26 So, this dissolution process is
04:28 essentially when an ionic or
04:30 polar compound is placed in
04:32 water and the water molecules
04:35 surround the ion over these
04:37 polar molecules. The positive end
04:39 of water molecules surround
04:40 negatively charged ions or regions,
04:43 while the negatively charged ends,
04:45 they surround the positively charged
04:46 ions or regions, pulling apart
04:48 the substance and dissolving it.
04:51 So when an ionic compound,
04:52 let's take, for example, table
04:54 salts, which is sodium chloride.
05:03 Now imagine that you guys
05:05 are pouring this table salt
05:06 into a cup of water.
05:08 What happens in a molecular
05:09 level is that the water
05:11 molecule surround the individual ions.
05:13 So I'm going to separate
05:14 this into a positive sodium
05:16 ion and a negative chloride
05:19 ion. So what happens is
05:21 these molecules separate from each
05:23 other when it is dissolved
05:25 in water. The negatively charged
05:27 oxygen end of the water
05:28 molecules surround cations. Now the
05:31 cation here, as we mentioned
05:33 before, is the sodium and
05:35 the amion is going to
05:36 So, the oxygen, the negatively
05:39 charged end, which is the
05:40 oxygen end, is going to
05:42 surround the cations like the
05:43 esoteum, and the positively charged
05:45 end, the hydrogen ends, are
05:46 going to surround the anions
05:48 like chloride. This process is
05:50 called solvation, and the cluster
05:54 of water molecules around an
06:04 Okay. Now this interaction, it
06:13 stabilizes the ions in solution
06:15 and it prevents them from
06:17 re -associating and keeping them
06:18 dissolved. So once you, let's
06:22 take our salt table salt
06:23 example again. So once you
06:24 guys put this table salt
06:27 you notice that it stays
06:29 dissolved. The table salt, it
06:31 does not separate back into
06:33 the spoon of table salt
06:34 that you once had. So
06:36 the interaction that we talked
06:37 about of the charges surrounding
06:39 the opposite charge, this is
06:41 what stabilizes the ions in
06:42 solution, prevents them from re
06:44 -associating and keeps them dissolved.
06:47 Okay, so let's look at
06:50 the biological importance of solubility.
06:53 So we've looked at a
06:55 couple of examples before, but
06:56 let me write them down
06:57 here. So one for the
06:59 transport of substances,
07:01 Now, water's ability to dissolve
07:11 a wide range of substances
07:13 essential for the transport of
07:15 nutrients, gases, waste products, and
07:17 biological organisms. For example, blood
07:20 plasma is primarily water and
07:22 can carry dissolved glucose electrolytes
07:24 and oxygen throughout the body.
07:29 importance of next biological importance
07:31 of solubility includes in chemical
07:33 reactions. So, most biochemical reactions,
07:43 including those that occur in
07:44 our cells, take place in
07:46 aqueous solutions. Enzymes and substrates
07:48 dissolve in water, allowing chemical
07:50 reactions to occur efficiently. So
07:52 that's what is so important
07:53 for chemical reactions to require
07:57 as a solvent. And the
08:00 fun point we're going to
08:01 look at is a process
08:03 known as homeostasis. So water
08:09 is the solvent properties help
08:10 maintain homeostasis by allowing the
08:13 body to regulate the concentration
08:15 of various solutes, ensuring that
08:17 cells and tissues function properly.