Photosynthesis-Summary Irish Leaving Cert-Only-(Ireland) Leaving Cert Biology Photosynthesis
Summary
TLDRThis video provides a concise summary of photosynthesis, focusing on key concepts for students revising for the Irish Leaving Cert. It explains how plants use light energy to convert carbon dioxide and water into glucose and oxygen. The video outlines the two main stages of photosynthesis: the light-dependent reactions, which occur in the chloroplast's thylakoid membranes, and the Calvin cycle, which occurs in the stroma. The importance of ATP and NADPH in this process is highlighted, along with the role of chlorophyll and photosystems. The video also covers leaf adaptations for efficient photosynthesis.
Takeaways
- 🌿 Photosynthesis is the process by which green plants make their own food using light energy.
- 🔬 NADPH and ATP are essential molecules for understanding photosynthesis.
- 🌱 Plants are autotrophs, meaning they can produce their own food, and are the producers at the base of the food pyramid in ecology.
- 🔆 Photosynthesis requires four factors: carbon dioxide, water, chlorophyll, and light.
- 🌳 The process mostly occurs in the leaves of plants, which are well adapted for photosynthesis.
- 🍃 Leaves are thin and flat to allow for rapid diffusion of gases and increased surface area for sunlight absorption.
- 🌿 Chlorophyll pigments are found in the thylakoid membranes of chloroplasts where photosynthesis takes place.
- 🔵 Chlorophyll absorbs light energy across the spectrum except for green and yellow, which are reflected.
- 🔄 There are two pathways in the light-dependent stage of photosynthesis: cyclic and non-cyclic.
- 💧 Photolysis of water occurs in the non-cyclic pathway, producing electrons, protons, and oxygen.
- 🔋 The light-independent stage, or Calvin cycle, uses ATP and NADPH to convert carbon dioxide into glucose.
Q & A
What is photosynthesis?
-Photosynthesis is the process by which green plants make their own food using light energy.
Why are plants called autotrophs?
-Plants are called autotrophs because they are capable of making their own food, which is a characteristic of photosynthesis.
What are the four factors necessary for photosynthesis?
-The four factors necessary for photosynthesis are carbon dioxide, water, chlorophyll, and light.
What happens if any of the four factors for photosynthesis are missing?
-If any one of the four factors is missing, photosynthesis will not occur.
Where does photosynthesis primarily take place in plants?
-Photosynthesis primarily takes place in the leaves of plants.
Why are leaves well adapted for photosynthesis?
-Leaves are thin and flat, allowing for rapid diffusion of gases and increased surface area for absorbing sunlight.
What is the role of the chloroplast in photosynthesis?
-The chloroplast is the site of photosynthesis within plant cells, containing structures called thylakoids where chlorophyll pigments are located.
What are the two types of photosystems mentioned in the script?
-The two types of photosystems mentioned are photosystem II and photosystem I.
What is the light-dependent stage of photosynthesis?
-The light-dependent stage of photosynthesis involves the absorption of light energy by pigments and the production of ATP and NADPH.
What is the light-independent stage of photosynthesis?
-The light-independent stage, also known as the Calvin cycle, uses the products ATP and NADPH from the light stage to convert carbon dioxide into glucose.
What is the role of NADPH in the Calvin cycle?
-NADPH carries electrons and protons to the Calvin cycle, where they combine with carbon dioxide to produce glucose.
What is the end product of the light stage of photosynthesis?
-The end products of the light stage are ATP, NADPH, and oxygen, with the latter being a result of photolysis of water.
Outlines
🌿 Photosynthesis Overview
This paragraph introduces the topic of photosynthesis, specifically tailored for the Irish Leaving Cert boundary course. It emphasizes the importance of understanding NADPH and ATP for grasping photosynthesis. Photosynthesis is described as the process by which green plants, known as autotrophs, produce their own food using light energy. The paragraph outlines the four essential factors for photosynthesis: carbon dioxide, water, chlorophyll, and light. It also presents the chemical equation for photosynthesis and explains how these elements come together in the leaves, which are adapted for rapid gas exchange and light absorption. The focus then shifts to the chloroplast, the site of photosynthesis, and the structure of the thylakoids and grana where chlorophyll is located.
🔬 The Light-Dependent Reactions of Photosynthesis
This section delves into the light-dependent stage of photosynthesis, which occurs in the thylakoid membranes of the chloroplast. It explains the role of pigments, particularly chlorophyll, in absorbing light energy across the spectrum, with the exception of green and yellow light, which are reflected. The paragraph describes two pathways within this stage: the cyclic pathway, involving only photosystem one, and the non-cyclic pathway, which involves both photosystems one and two. The cyclic pathway results in the formation of ATP, while the non-cyclic pathway leads to the production of ATP and NADPH, as well as oxygen through the photolysis of water. The paragraph also discusses the role of electrons in these processes and how they move through the electron transport chain.
🌱 The Light-Independent Reactions: Calvin Cycle
The final paragraph covers the light-independent stage of photosynthesis, also known as the Calvin cycle or dark reactions. It takes place in the stroma of the chloroplast and utilizes the products of the light-dependent stage, ATP and NADPH, to fix carbon dioxide into glucose. The paragraph explains how NADPH delivers electrons and protons to combine with carbon dioxide, facilitated by enzymes in the stroma. The breakdown of ATP provides the energy for these reactions, and the cycle is completed as ADP and phosphate are recycled back to the light-dependent stage to regenerate ATP. The summary concludes with a recap of the entire photosynthesis process, highlighting the interdependence of the light and dark stages and the importance of the chloroplast as the organelle where these reactions occur.
Mindmap
Keywords
💡Photosynthesis
💡Chloroplast
💡Thylakoid
💡ATP (Adenosine Triphosphate)
💡NADPH
💡Light-dependent reactions
💡Calvin cycle (Dark stage)
💡Chlorophyll
💡Photolysis
💡Photosystem
Highlights
Photosynthesis is the process by which green plants make their own food using light energy, which is why they are considered autotrophs.
The four factors necessary for photosynthesis are carbon dioxide, water, chlorophyll, and light.
The key equation for photosynthesis is: Carbon dioxide + Water + Light Energy → Glucose + Oxygen.
Photosynthesis mainly occurs in the leaves of plants because of their thin, flat structure, which allows for efficient gas exchange and increased surface area for light absorption.
The chloroplast is the site of photosynthesis, and inside it, the thylakoids and grana are responsible for light absorption.
Pigments like chlorophyll absorb different wavelengths of light, with chlorophyll absorbing most colors except green and yellow.
The light-dependent stage of photosynthesis occurs in the thylakoid membranes and involves two pathways: cyclic (pathway 1) and non-cyclic (pathway 2).
Pathway 1, the cyclic pathway, involves only Photosystem 1 and results in the production of ATP through electron transport.
Pathway 2, the non-cyclic pathway, involves Photosystem 2 and Photosystem 1 and produces ATP, NADPH, and oxygen through the photolysis of water.
Photolysis of water is essential in the non-cyclic pathway as it replaces the electrons lost in Photosystem 2 and produces oxygen as a byproduct.
The light-independent stage, or the Calvin Cycle, occurs in the stroma of the chloroplast and does not require light, but it needs ATP and NADPH produced in the light-dependent stage.
During the Calvin Cycle, carbon dioxide combines with electrons and protons carried by NADPH to produce glucose.
The breakdown of ATP during the Calvin Cycle provides the necessary energy for the synthesis of glucose.
The products of photosynthesis are crucial: glucose is used as an energy source, while oxygen is released into the atmosphere or used for plant respiration.
The light-dependent stage produces ATP and NADPH, while the Calvin Cycle uses these to convert carbon dioxide into glucose.
Transcripts
this is a summary video on
photosynthesis it's geared towards the
Irish Leaving Cert boundary course it's
made to help my class revise so please
be aware that it is a very much
summarized version of this topic so just
a little piece of advice generally if
you don't know about NADPH and ATP those
two molecules you will find
photosynthesis extremely difficult go
back and revise them first
photosynthesis is the process by which
green plants could make their own food
using light energy and it's one of the
reasons why we refer to plants as being
autotrophs their ultra trophic capable
of making their own food and it's also
the reason why plants are always found
at the bottom of the food pyramids in
ecology they are the producers so one of
the other things you have to know about
photosynthesis is that it's a biological
process where light energy is converted
to chemical energy by the plant there
are four factors necessary for
photosynthesis carbon dioxide water
chlorophyll and light and if any one of
these four factors is missing well then
photosynthesis simply will not happen
this is the equation that you need to
know for your exams
it describes what's going on in the
process of photosynthesis and it helps
you understand what's happening carbon
dioxide diffuses into the stomata of the
leaves water enters the roots by osmosis
and goes upwards to the leaves light
gets trapped by chlorophyll in the
chloroplast
of those plant cells and at the end of
the process glucose is produced and so
too is oxygen the process mostly happens
in the leaves of plants and the reason
for this is because the leaves are so
well adapted for photosynthesis how well
firstly the leaves are thin flat lamina
being very thin is good because it
allows for the rapid diffusion of carbon
dioxide into those cells and the rapid
diffusion of oxygen out of the leaf and
being flat means that it's very good
because it increases the surface area
for absorbing all of that sunlight so
that's just some of the adaptations of
the leaf but be aware that there is a
separate video and you have to know the
internal structure of the leaf very well
so I would watch that later on so let's
go into the specifics of what happens in
photosynthesis and the trick to this is
knowing the structure of the chloroplast
really well plant cells you know have
the
structures known as clear applause and
this is where photosynthesis takes place
inside the chloroplast you see these
green dislike structures flat structures
and they're called Tyler codes they're
usually stacked in two groups or bundles
known as a Granum and when you have a
few Granum it's referred to as grana so
it's inside these thylakoids are these
grana that you find the chlorophyll
pigment so chlorophyll and all the other
pigments are found in the membrane of
the thylakoid so you can see here this
is one single thylakoid and remember
that they're usually arranged in two
Granum photosynthesis is taking place in
the chloroplast and specifically we're
now looking at the membranes of the
thylakoids inside the chloroplast where
we find these substances known as
pigments these are capable of absorbing
different wavelengths of light energy
the most important is chlorophyll but
there is chlorophyll a and chlorophyll B
and many other types of pigments too
light is made up of a spectrum of seven
colors which represent different
wavelengths of light energy chlorophyll
the various types of chlorophyll are
very well suited to absorbing light
energy at either end of the spectrum so
they absorb most of the colors of white
light except for green and yellow which
are reflected to ensure that light is
harvested in a very efficient way the
pigment molecules are arranged into
these structures known as photo systems
in the thylakoid membranes photo systems
are basically the chlorophyll molecules
and the other pigments arranged next to
proteins and at the center of which is
this reaction center which contains
special chlorophyll molecules and an
electron acceptor that can accept the
electrons that are going to be excited
when they absorb all of that light
energy so there are two photosystems of
note there's photosystem ii and
photosystem one photosystem one was
discovered first and photosystem ii was
discovered second they're basically the
same except that their arrangement is
slightly different in that one can
absorb different wavelengths of energy
so the first part of photosynthesis is
the light dependent stage and there are
two pathways there is pathway one and
pathway two let's start with pathway one
it's known as the cyclic pathway and
it's happening in the thylakoid
membranes inside those chloroplasts and
it involves only photosystem one so
light energy gets absorbed by these
pigment
Jews that are arranged this photosystem
one the light energy is passed from
pigment molecule to pigment molecule
until it reaches a reaction center
chlorophyll
this results in electrons being
energized and are passed to an electron
acceptor molecule energized electrons
then get passed over an electron
transport chain losing a lot of their
excess energy and resulting in the
formation of ATP eventually those now
low energy electrons return back to
chlorophyll in photosystem one so now
let's go onto pathway 2 which is known
as the non cyclic pathway and you can
see from the diagram here that it
involves two photosystems photosystem 2
and photosystem one so pathway 2 begins
in much the same way as pathway 1 except
it begins with photosystem 2 where the
pigment molecules absorb their light
energy it gets passed from molecule to
molecule until it reaches the reaction
center chlorophyll here energized
electrons then are picked up by the
electron acceptor molecule and they are
eventually passed over an electron
transport chain where ATP is generated
the electrons continue on to photosystem
1 so you can see what has happened so
far in pathway to basically the
electrons have been energized they've
passed over an electron transport chain
generating a bit of ATP in the process
and now they've been passed into
photosystem 1 so we're halfway true
pathway to energized electrons have so
far left chlorophyll in photosystem 2
and gone to photosystem 1 so electrons
are now needed to replace those lost by
the chlorophyll in photosystem 2 so this
is when photolysis of water takes place
this is using light energy to split
water molecules and it's really done to
replace those electrons photolysis of
water produces three very important
products electrons protons and oxygen
the electrons go to replace those lost
by chlorophyll in photosystem two the
protons go into a proton pool and will
eventually be transported by NADPH to
the dark stage reactions or the Calvin
cycle and the oxygen either gets used
internally by the plant cell for
respiration but most of it gets released
to the atmosphere through the stomata so
let's recap energized electrons left
reaction Center chlorophyll in
photosystem 2 they were picked up by an
acceptor molecule and passed over an
electron transport chain
this resulted in the generation of ATP
they then made their way into
photosystem one which is now going to
absorb more light energy and results in
electrons being energized the electrons
are now going to be passed by that
acceptor molecule to a new molecule and
ADP and this is where they're trapped so
basically then you have this molecule
called nicotinamide adenine dinucleotide
phosphate and you have to know its full
name it's otherwise referred to as nadp+
it's going to combine or trap two
electrons and a proton those protons
from the proton pool remember and it's
going to form NADPH NADPH is a carrier
molecule it's going to carry those
electrons and that proton to the dark
stage of photosynthesis or the Calvin
cycle so the products of the non cyclic
pathway are ATP and NADPH the oxygen was
produced it was produced as a result of
photolysis of water so be very specific
so with the light stage completed we're
now on to the light independent stage
it's so called because it does not use
light or need light however it does need
the products that were formed in the
light stage that ATP and NADPH
so it's otherwise referred to as the
Calvin cycle or the dark stage reactions
the calvin cycle or the dark stage
reactions they take place in the stroma
of the chloroplast you can see here in
the diagram this contains many enzymes
and so all the factors that affect
enzyme controlled reactions such as
temperature and pH they can impact the
reactions of the calvin cycle also bear
in mind that the reactions of the light
stage that the light dependent reactions
these happen too quickly are too fast
and so are not enzyme controlled so
let's get back to the Calvin cycle
carbon dioxide which has diffused into
the stomata of the leaves is basically
going to combine with those electrons
and those protons that will be
transferred to the stroma by the
molecule NADPH once it transfers those
electrons and the proton it reverts back
to being nadp+ and it goes back to the
light dependent stage to do more work so
in the calvin cycle then carbon dioxide
combines with the electrons and the
protons to give glucose that
carbohydrate
and the reactions are all fueled by the
breakdown of ATP which was formed in the
light-dependent stage and you know that
when ATP breaks down it gives rise to
adp and a phosphate and that goes back
to the light-dependent stage to generate
some more ATP so this diagram is
excellent for helping you review just
what's gone on in photosynthesis so you
know that the whole process takes place
in these organelles known as
chloroplasts found in plant cells it
involves two types of reactions light
dependent reactions and light
independent reactions so the light stage
or the light dependent reactions happens
in the Granum or the grana the stacks of
thylakoids and it involves the photo
lysis of water so that's very unique to
the light stage important products such
as ATP and NADPH are formed as a result
of the light stage reactions are the
light dependent reactions and because of
photolysis of water oxygen is also
formed then the second stage of
photosynthesis is known as the calvin
cycle sometimes referred to as the dark
stage reactions it happens in the stroma
of the chloroplast so the liquid part of
the chloroplast and it involves the two
products made in the light dependent
stage ATP and NADPH
so NADPH is going to bring electrons and
protons which will then combine with the
carbon-dioxide to produce glucose and
all of their reactions are fueled by the
breakdown of ATP that was photosynthesis
I hope the video has helped in some way
with this topic because I know it's
tricky so the very best of look make
sure you go on and do pass papers now
and you go and use your textbook please
be aware that I do include a lot of
detail about photosystems they're not on
your course I just include them so that
if you want to go and look at other
videos such as kadek atom II which is
amazing and you'll be able to understand
them better if you know about
photosystems so best of luck and please
be aware that these videos are not
intended for commercial use and they're
not made for monetary gain good luck
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