Unit: 3 - Photosynthesis and energy capture Flashcards
what does photosynthesis convert light to?, and how is this new energy stored?
Photosynthesis converts light energy into chemical energy stored in carbohydrates (sugars) and other organic compounds
What are the raw requirements for photosynthesis?
This process consists of a series of chemical reactions that require carbon dioxide (CO2) and water (H2O)
What traps the light energy in photosynthesis?
The light energy is trapped by photosynthetic pigments such as chlorophyll
describe how light interacts with the plant(not photosynthesis directly), hints(: wavelength of light, how much is converted, does all of it get absorbed or is there other fates the light faces striking a leaf)
Only particular wavelengths of light that strike a leaf are absorbed by photosynthetic pigments but very little of the energy is actually converted into useful chemical energy. The rest of the light striking the leaf is either reflected off the leaf surface or is transmitted through the leaf. These processes are sometimes called the fates of light striking a leaf.
On average, what is the percentage of light that gets absorbed, reflected, and transmitted?
Absorbed: Light is taken into the leaf (5%).
Reflected: Light is bounced back from the leaf surface (85%).
Transmitted: Light passes through the leaf (10%).
What are the two main chlorophyll photosynthetic pigments, and what light wavelengths do they absorb?
Chlorophyll a and b are the main photosynthetic pigments, they absorb mainly blue and red light wavelengths.
What do carotenoids do?
The carotenoids extend the range of wavelengths absorbed and pass this energy onto chlorophyll.
What is the definition of photosynthesis?
Photosynthesis is a series of enzyme-controlled reactions that occurs in the chloroplasts of plants.
Name three quick bullet point facts about photosynthesis?
- In photosynthesis, organic molecules such as carbohydrates and amino acids are synthesized by the reduction of carbon dioxide.
- The energy to drive the reactions comes from light.
- Light energy is absorbed into the pigments contained in plant cell chloroplasts.
What dependency is the first stage of photosynthesis dependent on, and what is the stage called?
The first stage of photosynthesis is dependent on light and is often referred to as the light reaction.
What excites electrons?(don’t blame me, blame SQA terminology but excites likely means vibrating like a child going to an amusement park)?
If a pigment molecule absorbs light energy, an electron in the molecule becomes excited i.e. the electron’s energy level is raised to become a high-energy electron
What stage of respiration does these high-energy electrons get transferred to, and what does it produce?
These high-energy electrons can then be transferred through the electron transport chain to bring about production of ATP by the enzyme ATP synthase.
What else can the energy be used for?
The energy is also used for the photolysis of water
What does water split into?, and what co-enzyme does hydrogen get transferred to make NADPH?
Water is split into oxygen which is evolved as a by-product of the reaction, and hydrogen which is transferred to the coenzyme NADP and combined to produce NADPH
What’s the ATP and NADPH produced in the light reaction of photosynthesis used for?
The ATP and NADPH produced in the light reaction of photosynthesis are used in the next stage of photosynthesis referred to as the carbon fixation stage (Calvin Cycle).
What are the names of the second stage of photosynthesis?
The second stage of photosynthesis is known as the carbon fixation stage or the Calvin Cycle.
Does the carbon fixation stage require light?
no it doesn’t require light
What is carbon dioxide converted to suing ATP and NADPH from light reactions stage in the carbon fixation stage?
In this reaction carbon dioxide is converted into sugars using ATP and NADPH from the light reaction.
What is the shorter form of Ribulose-1,5-bisphosphate carboxylase oxygenase
The shorter form is RuBisCO
What enzyme in the carbon fixation stage fixes carbon dioxide in the atmosphere?
RuBisCo or Ribulose-1,5-bisphosphate carboxylase oxygenase
How does RuBisCO fix carbon dioxide in the atmosphere?
RuBisCO fixes carbon dioxide by attaching it to RibuloseBisPhosphate (RuBP) to form 3-phosphoglycerate.
How is glyceraldehyde-3-phosphate (G-3-P) formed?
The 3-phosphoglycerate produced is phosphorylated by ATP and combined with hydrogen from NADPH to form the stable compound glyceraldehyde-3-phosphate (G-3-P)
What is glyceraldehyde-3-phosphate(G-3-P) used for?
G-3-P is used to regenerate RuBP and for the synthesis of glucose
How may glucose be used for?
Glucose may be used as a respiratory substrate, synthesized into starch or cellulose or passed to other biosynthetic pathways.
What do the biosynthetic pathways do?
These biosynthetic pathways can lead to the formation of a variety of metabolites such as DNA, protein and fat.
