Hi. It's Paul Andersen. And in this is Life Science Core Idea 1A (LS1A).
It's on structure and function. In other words in nature, how does the form that an organism
have fit its function? And so when we're talking about structure and function it's important
that your students understand the difference between the two. Structure is the physical
appearance that you have. And so for example in this wrench, it has the number of different
structures. And so it's got this long arm. It's got this adjustable spanner, so I can
spin this on this side and the spanner is going to move on that side. These are all
structures. It's made of metal. It's very hard. These are all structures that this wrench
has, but it doesn't speak to their function. Function is going to be what it does. And
so when I spin this dial the adjustable spanner is going to change in this direction. I also
can move it up and down so I have a huge amount of leverage. Now we're talking about function.
And so in sciences we call these two things structure and function, anatomy and physiology.
Anatomy is what it is and physiology is what it does. But it's important that we work our
students through a nice progression. And so where should we start? In the lower elementaries
we should start by talking about structure and function. And so we can show them different
structures and they can come up with the function. And so if you were to look through these pictures
over here, what do they do? Well these are all eyes and so they'd be responsible for
vision or your hand is for grasping. These are feathers so they allow us to fly if we're
a bird, but also provide insulation. These are the needles on a pine tree. So those are
going to give us food. In other words do photosynthesis in plants. Or these spine are defensive or
flowers are reproductive. And so students should get this understanding in the lower
grades that the structure that organisms have fit the job that they do. But don't just set
yourself animals. We should always be talking about plants. And so what are some plant structures
here? Somethings that jump out right away like the roots and the stems and the leaves.
And then students should start to understand that each of these have function. The roots
remember are going to bring in water and that nutrients will move up throughout the stems
and the leaves are going to be a site of food production. It's where we're actually doing
photosynthesis. We're converting gases into actual sugars. And so an understanding of
structure and function is important but as you move through the elementary levels, we
want to talk about these four ideas. That these structures and functions or excuse me
these structures that organisms have fit these big functions. Growth, behavior, survival
and reproduction. So growth means we can get bigger or larger over time. Behavior is how
we respond to our environment. Survival is, can we survive? Do we die or not? And then
reproduction, can we pass our genes on to the next generation? And so we could point
at a number of different structures in this cat that allow it to grow, behave, survive.
So for example, its eyes allow it to gain information on its environment and can respond
to that using its muscles and its bones. And so now I'm talking about internal structures.
And so in elementary we should talk about structures on the inside and the outside of
organisms that allow them to do these big four things. But we should keep at the macro
level. We shouldn't be talking about cells yet. That's going to come when we get to the
level of middle school. And so as we move into middle schools students should understand
that life is made up of cells. All life is made of cells. Not all life is multicellular.
In other words this trout right here is made up of billions of cells and this paramecium
is made up of just one cell. And so no matter what, if we find life, make sure your students
know that life is built of cells. And those cells have to allow that organism to respond
to their environment. In other words they need to respond to flow of the water if you're
a trout, or changes in the concentration of salt if you're a paramecium. Or finding food.
So they need to be able to find food. They need to be able to get water. And they also
need to dispose of waste. So all organisms have to do that. And they use their cells
to do it. Now it's going to be at the level of a single cells, so a paramecium for example,
is going to pump out extra water that comes in through a contractile vacuole. In a trout
they're going to have to get rid of a lot of that excess water through urine that's
really dilute. And so they have solutions to all of these problems. But the solution
is at the level of a cell. They should also understand a little bit of the cell's structure.
And so don't beat them to death with memorizing all the parts of a cell, but there's some
major parts of a cell that they should really understand. So the cell membrane, for example,
is going to be around the inside of every cell and it regulates what goes in and out
of a cell. You could talk about the different types of cells. This would be prokaryotic
or bacterial cell. And this would be a eukaryotic cell. But there are some other structures
in here. So the DNA would be an important one that I'll talk about in just a second.
But don't just memorize everything. Make sure you're choosing some wise functions and structures.
Know how life is organized. And so every life form is made up of cells. And if they're multicellular
those cells are organized into tissues. The tissues make up organs. And then the organs
eventually make organisms. And so students should have an understanding of this level
of organization within an organism. As we move into high school we want to get into
more into the biochemistry of cells and structures within cells. So for example the importance
of water. What does water provide? Well it provides an aqueous environment for all these
cool chemical reactions to go on in a cell. And so all life requires water. There are
four major macromolecules that cells require or life requires. Those are proteins, carbohydrates,
lipids, and nucleic acids. Students should understand those four and what role they play.
Proteins pretty much build everything. So when you're looking at me you're looking at
proteins and the actions of proteins. Carbohydrates and lipids are going to provide energy, or
food to organisms. And at the cellular level as well. Carbohydrates can give us big structure
like cellulose in a plant. But lipids also give us structures. So the membranes, all
the membranes in a cell are going to made up of lipids. And then nucleic acids are going
to be the DNA and the RNA. And they're responsible for information inside cells. And so let's
go in a little bit deeper on that. The DNA in a eukaryotic cell is going to be found
in the nucleus. And that DNA is going to contain sections of it which are genes. So genes are
bits of DNA that code for a specific protein. And so there's basically information within
the nucleus that is information in the form of DNA. That information is transmitted out
into the cytoplasm by RNA but basically we're going to translate those genes into proteins.
Because proteins make up the cell. And so changes in the DNA result in changes in the
proteins. We also should emphasis the importance of feedback loops. So how to maintain an internal
environment as your environment changes. You do that through feedback loops. And there
are two feedback loops that we use. Positive feedback loops if we want to move away from
a set point. And so for example on this tree all the fruit are going to go ripe at the
same exact time. And we do that using a positive feedback loop. Basically one of the fruits
will give off a chemical called ethylene that will diffuse. Other fruits are going to pick
that up and now they're going to give off this gas as well. And so if we want everything
to occur all at once that's going to be a positive feedback loop. So for example, when
your body starts to be invaded by bacteria during an infection, we're going to have a
positive feedback loop that's going to bring white blood cells to that area. We also have
important negative feedback loops. That's when we want to keep our environment around
a set point. And so the internal temperature of most humans is around 37 degrees Celsius.
ANd so how do we maintain that? Well as our body temperature starts to drop, we're going
to do things like shiver. We're going to start to vasoconstrict, so we're going to keep our
capillaries constricted so blood doesn't loose heat to the environment. And that's going
to warm us up. What happens if we get too warm? We're going to sweat. We're going to
vasodialate and we're going to let some of that heat go. And so we're using feedback
loops to maintain that environment. And so the structures inside organisms fit their
function, what they do. And I hope that was helpful.