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at first plants might not seem all that
exciting and you might wonder why must i
learn about plants but plants are so
important for life they are producers
which means that they're the main
support for food webs many medications
that we have today are derived from
plants they produce oxygen for us to
breathe by the photosynthesis that they
do you know how there are many different
types of animals well there are many
different types of plants as well to get
to plant structure we need to outline
two major plant categories
vascular and non-vascular recall that in
the human body your vascular system
includes arteries and veins well plants
don't have arteries or blood for that
matter when we're talking about a
vascular system in plants we're talking
about two major types of tubes or
vessels called the xylem and phloem the
xylem carries water xylem is found
throughout a vascular plant water is
absorbed from the roots of a vascular
plant and carried upwards
roots are specially designed to help
anchor plants and also to absorb the
water found in the soil that they are in
the phloem carries sugars which are
typically produced in the leaves of the
plants during photosynthesis
this sugar is their food source that
plants make in photosynthesis
it needs to be carried throughout the
plant the phloem might start with a p
but you know it has that same f sound
that food has so it helps me remember
that it carries the plant's food
if a plant is non-vascular it does not
have vessels like the xylem and phloem
however it still needs water and it
still produces sugar it can't carry
water upwards in the xylem because it
doesn't have one that means non-vascular
plants typically are limited in size a
giant tree needs a xylem for water
transport that water is being carried
against gravity
non-vascular plants instead get their
water by osmosis
kind of like soaking up water like a
sponge a great example of a non-vascular
plant is moss
so remember vascular plants they have
xylem and phloem vascular tissue
and non-vascular plants they don't
much of a plant structure is actually
designed to facilitate photosynthesis
photosynthesis is the ability to make
sugar the plant's own food source from
sunlight we cannot do this you might be
able to go in the kitchen to make a
sandwich but you're just preparing your
food wouldn't it be amazing if you could
go out in your backyard and sunbathe and
conjure up a sandwich in your stomach
our little analogy is not perfect but
you can get what a big deal
photosynthesis is
if you understand the importance of this
function for plants you can really
understand many structure adaptations
that plants have photosynthesis needs
three major reactants to work water
light and carbon dioxide
now water we mentioned already how a
plant can get its water in different
ways depending on whether they're
vascular or non-vascular
so what about the other two reactants
the light and the carbon dioxide so
starting with the sunlight how does
plant structure deal with that
well plant cells have organelles called
chloroplast they are the site of
photosynthesis so they help capture
light energy for the process of
photosynthesis
this is a complicated process that is
made up of a light dependent reaction
and a light independent reaction also
called the kelvin cycle it's a big
enough process that we'll have to have
another video clip to cover that
but the leaf structure is designed to
capture this light energy with their
chloroplast
the other reactant on our photosynthesis
checklist is carbon dioxide so how does
the structure of plants help them obtain
carbon dioxide
first of all please realize that plants
do something in addition to
photosynthesis called cellular
respiration
just like you and they do need the gas
oxygen but they typically produce more
oxygen than they use which makes them
helpful as oxygen producers for
photosynthesis plants need the gas co2
carbon dioxide this is the gas
conveniently that we exhale which means
that we breathe this gas out
many plants have these fascinating
little openings
pores really called stomata
stomata is the plural and stoma is the
singular form of that word stomata are
typically found on the bottom of leaves
and in some species they're actually on
the top
stomata have a major role in gas
exchange gases can flow in through the
stomata and out through the stomata and
the co2 that enters is really needed for
photosynthesis there's only one little
problem the plant can't keep those
stomata open all the time why
well water will escape and remember
plants need water too for photosynthesis
so the plant has to determine whether to
open or close its stomata
it does this with the help of guard
cells if guard cells have the stomata
open it gets the gases it needs but it
can lose water if guard cells have the
stomata closed it gets to save its water
but then it can't get any gases
at night most plants with a few
exceptions that we'll talk about towards
the end close their stomata because they
can conserve water
at night they can't do much
photosynthesis because there's not much
sunlight so what's the point in keeping
stomata open during sunny days most
plants tend to open their stomata to get
the gases they need to do the
photosynthesis
but if the day gets way too hot and the
plant is low on water it may close its
stomata
different plant species have different
kinds of adaptations in their structure
to help them survive because if one
thing is true about plants they are
survivors here are some great examples
of plant structure adaptations that help
them with various functions plants that
have to conserve water they tend to have
very thin leaves so they don't have much
surface area and that way they don't
lose that much water think about pine
trees with their skinny pine needles
or think about the plants that live in
the desert remember how we said that
most plants close their stomata at night
well some desert plants have adapted by
opening their stomata at night when it's
not ridiculously hot and they have a
specialized way to store the gases they
need for the daytime this allows them to
close their stomata during the day to
prevent water loss during the hot desert
sun
plants that have a lot of access to
water but maybe are shaded by lots of
taller plants in the jungle they might
have really broad wide leaves so they
can soak up as much sun as possible
it's hard to live in someone else's
shadow since there's plenty of water
these big leaved plants don't have to
worry about all the surface area losing
water because there's plenty of water to
go around
or have you heard about carnivorous
plants like the venus fly trap or the
pitcher plant these plants still do
photosynthesis to make their sugar
but carnivorous plants also have the
ability to digest insects typically by
using special enzymes in a juice that
they secrete these plants tend to live
in areas where the soil is low in
nitrogen
plants and other organisms use nitrogen
to make proteins insects are a great way
to supplement this nitrogen need if you
ever look at the ingredients in plant
fertilizer you'll find that fertilizers
are typically high in nitrogen and you
know when people hang up mistletoe
so sweet right you're supposed to get a
kiss under it
is it terribly ironic that you are
hanging out a potentially parasitic
plant that uses its roots to steal
nutrients and water from its host plant
plants also have some amazing
reproductive adaptations but we have
another clip for that
well that's it for the amoeba sisters
and we remind you to stay curious
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you