CH 10 BIO MO2A

Function of the leaf

Function of the leaf

the main (but not only) organ responsible for turning sunlight into food

Function of the vein

transport water and minerals from the stem to the leaf cells through its xylem component, while simultaneously transporting the sugars produced by photosynthesis from the leaf to the rest of the plant via its phloem component

Function of the Mesophyll cell

carrying out photosynthesis by containing a large number of chloroplasts, which capture sunlight to convert carbon dioxide and water into glucose and oxygen

Function of the Chloroplast

the site of photosynthesis, where sunlight energy is captured and converted into chemical energy, producing glucose (sugar) from carbon dioxide and water while releasing oxygen as a byproduct

Function of the Stomata

act as controlled openings to allow for gas exchange between the plant and its environment, primarily taking in carbon dioxide for photosynthesis and releasing oxygen while also regulating water loss through a process called transpiration

Function of the outer membrane

acts as a barrier that is highly permeable to small molecules, allowing them to freely enter the chloroplast while still maintaining a selective control over larger molecules

Function of the inner membrane

a barrier to regulate the movement of molecules necessary for the Calvin cycle while allowing access to the enzymes within the stroma needed for carbon fixation

Function of the inner membrane space

serves as the location for the light-independent reactions (Calvin cycle) of photosynthesis, where carbon dioxide is fixed into organic molecules using the energy produced during the light-dependent reactions

Function of the Stroma

serves as the site for the light-independent reactions of photosynthesis

Function of the Thylakoid

the site where the light-dependent reactions of photosynthesis occur, absorbing light energy through chlorophyll pigments embedded in its membrane to produce ATP and NADPH, essential molecules for the process of photosynthesis

Function of the Granum

maximize the surface area for light absorption during the light-dependent reactions of photosynthesis

Function of the Thylakoid space

serve as the site where the light-dependent reactions of photosynthesis occur, specifically by accumulating hydrogen ions (protons) to create a concentration gradient used for ATP production during the electron transport chain

equation for the photosynthesis reaction

6CO2 + 6H2O → C6H12O6 + 6O2

purpose of photosynthesis

making food" for themselves by producing sugar (glucose) from carbon dioxide and water, while also releasing oxygen as a byproduct

source of the carbon for photosynthesis

plants take in carbon dioxide (CO2) and water (H2O) from the air and soil

products of photosynthesis

carbon dioxide and water are combined using light energy to create glucose and release oxygen as a byproduct

photosynthesis is exergonic or endergonic and the source of energy?

endergonic reaction

the source of this energy is sunlight which is absorbed by chlorophyll in plants to power the process of converting carbon dioxide and water into glucose and oxygen. 

Van Neil’s experiment to discern if the oxygen atoms in oxygen gas (O2) produced in photosynthesis are derived from carbon dioxide or water

by comparing this process to plant photosynthesis, he concluded that the oxygen released by plants comes from water molecules, not carbon dioxide, as the oxygen atoms in the released oxygen were derived from the water molecule that was split during photosynthesis, not from carbon dioxide

Ruben’s experiment to discern if the oxygen atoms in oxygen gas (O2) produced in photosynthesis are derived from carbon dioxide or water

the oxygen produced during photosynthesis comes from water, not carbon dioxide; when they used water labeled with heavy oxygen, the released oxygen also contained the heavy oxygen isotope, confirming water as the source of oxygen in photosynthesis.

photon

the basic unit of light energy, a tiny particle that carries electromagnetic radiation, essentially a "packet" of light with no mass and no charge

pigment

a naturally occurring colored substance found in plant or animal cells that gives tissue its color by selectively absorbing certain wavelengths of light

y r leaf gren

they contain a pigment called chlorophyll, which absorbs red and blue light from sunlight while reflecting green light back to our eyes

spectrophotometer

measures the amount of light absorbed by a sample at specific wavelengths

Analyze a spectral scan

a technique that examines a signal's content by analyzing its frequencies or wavelengths

which wavelengths of light are absorbed and which are not absorbed

Plants primarily absorb blue and red wavelengths of light, while largely reflecting green wavelengths

Which wavelengths promote photosynthesis, and which do not?

The wavelengths of light that most effectively promote photosynthesis are red light (around 600-700nm) and blue light (around 400-500nm), while green light is the least effective for photosynthesis because it is largely reflected by chlorophyll

wavelengths promote growth of filamentous alga

Filamentous algae primarily grow best under blue and red wavelengths of light

structure and function of chlorophyll

its structure consists of a central magnesium atom surrounded by a porphyrin ring, with a long hydrocarbon tail called a phytol chain attached, allowing it to anchor within the chloroplast membrane, and its function is to capture light energy from the sun, specifically blue and red wavelengths, which is then used to convert carbon dioxide and water into glucose and oxygen during photosynthesis

function of xanthophyll and carotene

accessory pigments in plants, primarily absorbing light energy from the sun and transferring it to chlorophyll for photosynthesis, while also providing photoprotective benefits by preventing damage from excessive light energy through their antioxidant properties

how chlorophyll and other pigments capture radiant energy

absorbing specific wavelengths of light from the sun, which excites electrons within their molecular structure, allowing them to move to a higher energy level, and then transferring this energy to the reaction center of a photosystem where it can be used to drive the chemical reactions of photosynthesis

Describe P680 and explain the purpose of P680

when energized by light, P680 releases a high-energy electron to an electron acceptor, replenishing its lost electron by extracting one from water molecules, effectively splitting water into oxygen, hydrogen ions, and electrons

Describe pheophytin and explain the function of pheophytin.

pigment molecule, essentially a chlorophyll molecule without a magnesium ion, that acts as the primary electron acceptor in Photosystem II during photosynthesis

what reaction occurs during photosystem II

splitting of water molecules, using light energy, to generate oxygen gas, electrons, and hydrogen ions

electron transport chain in photosystem II

involves the initial absorption of light energy by a chlorophyll molecule within the reaction center, causing an electron to become excited and transferred to a primary electron acceptor

the thylakoid lumen becomes acidic, while the stroma becomes basic

The energy stored in an H+ ion gradient is primarily used to synthesize ATP (adenosine triphosphate)

the final electron acceptor from the second electron transport chain

(Photosystem II) is plastoquinone

What is produced during the electron transport chain in photosystem I?

NADPH (nicotinamide adenine dinucleotide phosphate) and ATP are produced

products from the light reactions are used in the Calvin cycle?

ATP and NADPH (electron donor)

Describe carbon fixation and explain the roles of carbon dioxide, ribulose bisphosphate, and Rubisco

Carbon fixation is the process where inorganic carbon dioxide (CO2) from the atmosphere is converted into organic molecules, primarily by plants during photosynthesis, with the key enzyme being Rubisco which combines CO2 with a 5-carbon sugar molecule called ribulose bisphosphate (RuBP) to initiate the process; essentially "fixing" carbon into a usable form for the organism

happen during the calvin cycle in the stroma

why ATP and NADPH are needed in the Calvin cycle

they provide the necessary energy and electrons to convert carbon dioxide into a usable sugar molecule (like glucose), essentially acting as the power source for the chemical reactions that occur within the cycle; ATP supplies the energy needed for phosphorylation reactions, while NADPH acts as a reducing agent, donating electrons to reduce carbon compounds during the process of carbon fixation.

to convert the six molecules of 3-PGA into six molecules of a chemical called glyceraldehyde 3-phosphate (G3P)

how glyceraldehyde 3 phosphate is used (2 uses)

as a key intermediate in the process of glycolysis to generate energy in the form of ATP, and in the Calvin cycle of photosynthesis to build carbohydrates like glucose

the final product of Calvin cycle. Explain why Calvin cycle is a cycle.

glyceraldehyde-3-phosphate (G3P), a three-carbon sugar molecule which can be used to build larger carbohydrates like glucose

it regenerates the starting molecule, ribulose 1,5-bisphosphate (RuBP), allowing the process to continue repeatedly, fixing carbon dioxide from the atmosphere to produce sugars using energy from ATP and NADPH generated in the light reactions of photosynthesis

stomata

tiny pores or openings present on the surface of plant leaves, surrounded by specialized cells called guard cells, which regulate the exchange of gases like carbon dioxide and oxygen between the plant and its environment

opening stomata

allows them to take in carbon dioxide from the atmosphere

disadvantage of opening stomata

it leads to excessive water loss from the plant through transpiration

what can build up when stomata close

carbon dioxide (CO2) can build up inside the leaf because the pores through which it normally enters are shut, potentially impacting the plant's ability to photosynthesize effectively

photorespiration

a process in plants where the enzyme RuBisCO, which is responsible for carbon fixation during photosynthesis, accidentally binds to oxygen instead of carbon dioxide, leading to a wasteful release of carbon dioxide and a decrease in photosynthetic efficiency, particularly under conditions of high light intensity and temperature

what a C3 plant is and give examples of C3 plants

a plant that uses the C3 carbon fixation pathway during photosynthesis. a plant that uses the Calvin cycle for photosynthesis, where the first stable compound produced during carbon fixation has three carbon atoms, called 3-phosphoglyceric acid (3-PGA)

rice, wheat, barley, soybeans, spinach, cotton, and sunflowers

C4 Plants

maize, sugarcane, and sorghum

plants that use a specialized photosynthetic pathway, called the C4 pathway, to fix carbon dioxide by initially forming a four-carbon compound, which allows them to significantly minimize photorespiration by concentrating CO2 around the Rubisco enzyme in specialized cells

carbon fixation occurs in mesophyll cells while Calvin cycle occurs in bundle-sheath cells.  

CAM Plants

cacti, pineapples, and many succulents

are plants adapted to arid environments that minimize water loss by opening their stomata at night to absorb carbon dioxide and store it as an organic acid (malate), which is then used for photosynthesis during the day when the stomata are closed, effectively avoiding photorespiration by concentrating CO2 around the Rubisco enzyme

autotroph

an organism that can produce its own food using light, water, carbon dioxide, or other chemicals

heterotroph

an organism that cannot produce its own food and must obtain nutrition by consuming other organisms