Photosynthesis (UPDATED)
Summary
TLDRThe video script explores the fascinating process of photosynthesis, a vital ability of plants that also benefits humans by producing oxygen. It delves into how plants convert light into glucose, a process involving light-dependent reactions in chloroplasts and the Calvin Cycle. The script highlights the role of chlorophyll in capturing light and the adaptations plants have developed for efficient photosynthesis, such as CAM photosynthesis in cacti, to conserve water in arid environments. The Amoeba Sisters encourage viewers to stay curious about the intricacies of this essential biological function.
Takeaways
- šæ Photosynthesis is a special ability of plants that the speaker wishes to have, as it allows plants to produce their own food and oxygen.
- š± The process of photosynthesis is crucial for life on Earth, as it is a primary source of food and oxygen for many organisms, including humans.
- š The balanced equation for photosynthesis involves the conversion of carbon dioxide and water into glucose and oxygen using sunlight.
- š Plants use pigments, such as chlorophyll, to capture light of different wavelengths, which is why they appear green due to the reflection of green light.
- š Photosynthesis consists of two major reactions: the light-dependent reactions that occur in the thylakoids and produce ATP and NADPH, and the light-independent reactions or Calvin Cycle that take place in the stroma.
- š§ Water is a reactant in photosynthesis and is split during the light-dependent reactions, releasing electrons, protons, and oxygen.
- š± The Calvin Cycle uses ATP and NADPH from the light-dependent reactions to fix carbon dioxide into a usable organic form, ultimately producing glucose.
- š¬ Stomata are the pores on plant leaves that allow for the intake of carbon dioxide; plants can regulate the opening and closing of these pores.
- šµ Some plants, like cacti, use a special adaptation called CAM photosynthesis, which allows them to open their stomata at night to capture carbon dioxide and minimize water loss during the hot daytime.
- š¬ The script highlights the complexity of photosynthesis and encourages further exploration of the topic, such as the details of the photosystems and the steps in the Calvin Cycle.
- š³ Plants have various adaptations to perform photosynthesis efficiently in different environments, including diversity in leaf shapes, coverings, and pigments.
Q & A
What special ability related to plants does the speaker express a desire to have?
-The speaker expresses a desire to have the ability to perform photosynthesis, just like plants.
Why is photosynthesis important for humans even though we cannot perform it ourselves?
-Photosynthesis is important for humans because it produces oxygen, a gas that we need to breathe, and it is also the process by which plants make glucose, a sugar that is a fundamental part of our diet.
What is the balanced overall equation for photosynthesis as mentioned in the script?
-The script does not provide the exact balanced chemical equation for photosynthesis, but it is generally represented as: 6CO2 + 6H2O + light energy ā C6H12O6 + 6O2, which means six molecules of carbon dioxide and six molecules of water, using light energy, are converted into one molecule of glucose and six molecules of oxygen.
How is glucose related to both photosynthesis and cellular respiration?
-Glucose is a product of photosynthesis, which plants use to make their own food. In cellular respiration, both plants and animals break down glucose to produce ATP, the energy currency for cells.
What role do pigments play in the process of photosynthesis?
-Pigments, such as chlorophyll, play a crucial role in photosynthesis by capturing light, which provides the energy needed for the process to occur.
Why do many plants appear green to our eyes?
-Many plants appear green because chlorophyll, the pigment they use to capture light, reflects green light rather than absorbing it.
What are the two major reactions that occur in the chloroplasts during photosynthesis?
-The two major reactions are the light-dependent reactions and the light-independent reactions, also known as the Calvin Cycle or dark reaction.
What occurs during the light-dependent reactions of photosynthesis?
-During the light-dependent reactions, light is captured, water is split into electrons, protons, and oxygen, and ATP and NADPH are produced, which are used in the next stage of photosynthesis.
What happens in the light-independent reactions, also known as the Calvin Cycle?
-In the Calvin Cycle, carbon dioxide is fixed into a more usable organic form with the help of ATP and NADPH from the light-dependent reactions, ultimately leading to the production of glucose.
How do plants regulate the intake of carbon dioxide and prevent water loss, especially in harsh environments?
-Plants can regulate the intake of carbon dioxide and prevent water loss by opening and closing their stomata. Some plants, like cacti, use a process called CAM photosynthesis, where they open their stomata at night to capture carbon dioxide and store it chemically for use during the day when the stomata are closed.
What is CAM photosynthesis, and how does it help plants in hot desert environments?
-CAM photosynthesis is an adaptation that allows plants, like cacti, to open their stomata at night when it's cooler to capture and store carbon dioxide, which they then use during the day with their stomata closed, thus conserving water in the hot desert sun.
Outlines
šæ The Wonders of Photosynthesis
The video script introduces the concept of photosynthesis, a process that the narrator wishes they could perform like plants. Photosynthesis is highlighted as a crucial process not only for plants to produce their own food but also for its byproduct, oxygen, which is vital for humans. The script explains that plants, along with some protists and bacteria, can perform photosynthesis, emphasizing the importance of plants as primary producers in food webs and sources of food and medicine. The process of making glucose from sunlight is contrasted with cellular respiration, showing a reciprocal relationship between the two. The role of pigments, particularly chlorophyll, in capturing light for photosynthesis is discussed, and the unique ability of plants to reflect green light is noted, explaining why plants appear green.
š± Delving into the Mechanisms of Photosynthesis
This paragraph delves deeper into the two main reactions of photosynthesis: the light-dependent reactions and the light-independent reactions, also known as the Calvin Cycle. The light-dependent reactions occur in the thylakoids of the chloroplasts, where light energy is captured to split water molecules into electrons, protons, and oxygen, also generating ATP and NADPH. The light-independent reactions take place in the stroma and involve the fixation of carbon dioxide into an organic form, using ATP and NADPH from the previous reactions. The complex series of pathways in the Calvin Cycle ultimately produces glucose. The script also touches on the adaptations plants have developed to perform photosynthesis efficiently in various environments, with a specific mention of CAM photosynthesis in cacti as a strategy to conserve water in arid conditions.
Mindmap
Keywords
š”Photosynthesis
š”Chlorophyll
š”Light-dependent reactions
š”ATP (Adenosine Triphosphate)
š”NADPH
š”Calvin Cycle
š”Stomata
š”CAM Photosynthesis
š”Glucose
š”Pigments
š”Adaptations
Highlights
The speaker daydreams about having a special ability like a plant's photosynthesis, which is a unique process not found in humans or amoebas.
Photosynthesis is a vital process for plants, producing oxygen and glucose, which are essential for life on Earth.
Plants are major producers in food webs, and many of our medications and foods are derived from them.
The process of photosynthesis involves making glucose, a sugar that both plants and humans need for energy.
The balanced equation for photosynthesis is presented, showing its similarities to aerobic cellular respiration.
Plants have adaptations to perform photosynthesis in various environments, including the use of pigments to capture light.
Chlorophyll, a pigment found in chloroplasts, absorbs red and blue light but reflects green light, contributing to the green appearance of plants.
Photosynthesis consists of two major reactions: light-dependent reactions and light-independent reactions (Calvin Cycle).
Light-dependent reactions occur in the thylakoids of chloroplasts, where light is captured and water is split to produce oxygen, ATP, and NADPH.
The Calvin Cycle, or light-independent reactions, take place in the stroma of chloroplasts and use ATP and NADPH to fix carbon dioxide into glucose.
Carbon dioxide enters the Calvin Cycle through stomata, which are pores on the leaves that plants can open and close.
The process of photosynthesis is complex and involves a series of pathways that convert fixed carbon dioxide into glucose.
Plants have adaptations for efficient photosynthesis, such as CAM photosynthesis in cacti, which allows them to open stomata at night to avoid water loss during the day.
The video provides further reading links for those interested in exploring the details of photosynthesis, including the role of photosystems and the steps in the Calvin Cycle.
The video emphasizes the importance of understanding photosynthesis for appreciating the role of plants in ecosystems and human life.
The speaker encourages viewers to stay curious and explore the fascinating world of plant biology and photosynthesis.
Transcripts
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Iāve daydreamed before about what itād be likeĀ to have a special ability that other organismsĀ Ā
can do. Something that humans - or amoebas -Ā cannot. For example, to be able to fly likeĀ Ā
a peregrine falcon. Or to be able to walk up wallsĀ without any gear ā like a Texas banded gecko.Ā Ā
But if I told you I really wishĀ I could have a special ability ofĀ Ā
a plant ā youād probably be confused.Ā What can a plant do thatās so amazing?
Thereās a lot of cool things about plantsĀ actually. But, in particular, I really wishĀ Ā
I could do photosynthesis. And itās not justĀ plants that can do this process. For example, someĀ Ā
protists and some bacteria can too. ButĀ plants will be our focus for this video clip.Ā Ā
Animals and amoebas may have missed out on thisĀ ability, but we benefit from it greatly as thisĀ Ā
process also produces oxygen. A gas that we need.Ā Any process that plants themselves need to surviveĀ Ā
is important to us ā because plants in generalĀ are major producers making them indispensableĀ Ā
in food webs. Many of our medications andĀ foods come from plants. We need plants.Ā Ā
So understanding the nature of the process thatĀ plants use to make their own food is paramount.
So when I say make their own food, IāmĀ talking about making a sugar that they need.Ā Ā
Specifically, glucose. You need glucose too,Ā Ā
but you get it from what you eat. Plants, however,Ā get to make their own glucose in photosynthesis.
Here is the balanced overall equation forĀ photosynthesis, similar to what youāll findĀ Ā
in many introductory biology textbooks. AsĀ you will notice, it has some similarities toĀ Ā
aerobic cellular respiration. Recall thatĀ cellular respiration is used to make ATP,Ā Ā
which is an energy currency, and itāsĀ done by plants as well as animalsĀ Ā
and a lot of other organisms too. You can seeĀ how these reactants (inputs) of photosynthesisĀ Ā
are included in the products (outputs)Ā in cellular respiration. And the productsĀ Ā
(outputs) of photosynthesis are included in theĀ reactants (inputs) of cellular respiration. WhileĀ Ā
this doesnāt mean that theyāre simply reversed,Ā it is interesting to see what they have in common.
So while both plants and animals need glucose forĀ cellular respiration, plants donāt have to be inĀ Ā
search of glucose. Because they make it. PlantsĀ have adaptations to carry out photosynthesis inĀ Ā
a variety of environments. One thing plants haveĀ to do is capture light. Plants can use lightĀ Ā
capturing molecules called pigments. Recall thatĀ visible light has different wavelengths and thoseĀ Ā
different wavelengths of light have differentĀ colors. If youāve ever played with a prism before,Ā Ā
you can see how light can be separated into aĀ rainbow of colors due to different wavelengths.
So, a pigment that plants commonly use to captureĀ light is chlorophyll. Chlorophyll does a greatĀ Ā
job at absorbing red and blue light ā but not soĀ much green light. Chlorophyll reflects green lightĀ Ā
and this is one reason why manyĀ plants appear green to our eyes.Ā Ā
There are pigments besides chlorophyll thatĀ work with different wavelengths of light,Ā Ā
and this can explain why green isĀ not the only color you see in plants.
Chlorophyll is a pigment that can be found in theĀ chloroplasts of plants cells. There are two majorĀ Ā
reactions that occur in the chloroplastĀ that, together, make up photosynthesis.Ā Ā
They are: the light dependent reactionsĀ and the light independent reactions.Ā Ā
The light independent reactionsĀ can also be called the Calvin CycleĀ Ā
or evenā¦less commonlyā¦the darkĀ reaction. Sounds intriguing.
Weāre going to talk about both of these brieflyĀ and please remember, like most of our videos,Ā Ā
this is pretty general. Weāve gotĀ some further reading links in theĀ Ā
video description where youĀ can explore a lot more detail.
So light dependent reactions: happen inĀ the thylakoids. Little compartments in theĀ Ā
chloroplasts that contain pigment. A collectiveĀ stack would be a granumā¦multiple stacks wouldĀ Ā
be grana. In the light dependent reactions, lightĀ is captured and water (which is a reactant in theĀ Ā
photosynthesis equation) is āsplit.ā That meansĀ if you think of the chemical formula for waterĀ Ā
which is H20---it is split so that youĀ get electrons, protons, and oxygen.Ā Ā
So, oxygen is also a product ofĀ the light dependent reactions.
The light dependent reactions also produce ATPĀ and NADPH, which weāll get to in a little bit.Ā Ā
Both the ATP and the NADPH will be neededĀ for the next process: the light independentĀ Ā
reactions. Also known as the Calvin Cycle orĀ Dark Reaction. The name is bit misleading. While,Ā Ā
yes, this process isnāt directly capturingĀ light, it doesnāt require darkness either.Ā Ā
And, again, it will need items from the lightĀ dependent reactions like the ATP and NADPH. TheĀ Ā
light independent reactions still happen inĀ the chloroplast. But specifically, the lightĀ Ā
independent reactions happen in the stroma. TheĀ stroma is a fluid outside of the thylakoids.
In the Light Independent Reactions -or CalvinĀ Cycle- carbon dioxide enters. It is taken inĀ Ā
through pores ā that are often but not always onĀ the bottom of leaves ā and those pores are calledĀ Ā
stomata. Plants have the ability to open andĀ close their stomata. The carbon dioxide gas entersĀ Ā
the stomata and will be fixed. By fixed, I meanĀ that, with the additional help of a major enzyme,Ā Ā
the inorganic carbon dioxide is changed to a moreĀ usable organic form. The ATP that had come fromĀ Ā
the light dependent reactions will act as anĀ energy currency for the Calvin Cycle. The NADPHĀ Ā
that had come from the light dependentĀ reactions will supply reducing power----byĀ Ā
that, I mean that it helps add highĀ energy electrons to this process.Ā Ā
So, in a very complex series of pathways,Ā the fixed carbon dioxide, ATP, and NADPHĀ Ā
are used to make a product that- ultimately -Ā can be converted into glucose. A sugar. Phew.
So, letās take a look at this equation. Last time,Ā I promise. So, we have here the circled itemsĀ Ā
from the light dependent reactions. AndĀ now, notice the other items----the CO2Ā Ā
on the reactant side and the glucose on theĀ product side---those were from the Calvin Cycle.
Remember, there is so much more detailĀ to explore in this amazing process.Ā Ā
You can learn about the photosystemsĀ that are in the light dependent reactionsĀ Ā
or the detail of all the steps in the CalvinĀ Cycle and how ATP and NADPH will be convertedĀ Ā
to ADP and NADP+ which can then be usedĀ again by the light dependent reactions.
But before we end our short video, we do want toĀ mention that plants have some amazing adaptationsĀ Ā
that help them perform photosynthesisĀ efficiently in different environments.Ā Ā
Many of these adaptations can involveĀ the diversity of leaf shapes, coverings,Ā Ā
and pigments. This is definitely worthyĀ of a completely separate video topic, butĀ Ā
to give a neat example of an adaptationĀ involving photosynthesis: consider the cactus.
Cacti have a potential problem. They oftenĀ live in a hot desert, and so if they open theirĀ Ā
stomata during the hot day to get their carbonĀ dioxide, they can easily lose more water thanĀ Ā
would be ideal. The precious water can escapeĀ through the stomata if the stomata are open,Ā Ā
and that will happen at a faster rate in the hotĀ desert sun. But cacti, and some other plants too,Ā Ā
can do something called CAM photosynthesis. In CAMĀ photosynthesis, plants can open their stomata atĀ Ā
night ā when itās not so hot -and they can captureĀ carbon dioxide and chemically store it. They canĀ Ā
then use this carbon dioxide the next day when theĀ sun is shining and yet have their stomata closed,Ā Ā
allowing them to avoid having to openĀ their stomata in the heat of the day. Well,Ā Ā
thatās it for the Amoeba Sisters,Ā and we remind you to stay curious.
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