Chapter 11 Flashcards
What are chloroplasts?
Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide gas to produce food for the plant.
What is photosynthesis?
The process by which green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water.
What are Autotrophs?
“Self-Feeders” They sustain themselves without eating anything derived from other living beings. They produce their organic molecules from CO2 and other inorganic raw materials.
True or False? Plants are not autotrophs.
False, almost all plants are autotrophs.
What are photoautotrophs?
Organisms that use light energy to drive the synthesis of organic molecules from carbon dioxide and water.
What are Heterotrophs?
A heterotroph is an animal that can’t make its own food supply, so they have to eat other things, like plants or other animals, to survive
What is the endosymbiont theory?
an evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms
What are chloroplasts?
a plastid in green plant cells which contains chlorophyll and in which photosynthesis takes place.
Where are chloroplasts usually found?
The cells of the mesophyll, the tissue in the interior of the leaf
What is stroma?
The colorless fluid surrounding the grana within the chloroplast. Within the stroma are grana (stacks of thylakoid), and the sub-organelles or daughter cells, where photosynthesis is commenced before the chemical changes are completed in the stroma.
What is the thylakoid?
Thylakoids are membrane-bound compartments or sacs inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis
What is the thylakoid space?
The thylakoid space is the space inside of the thylakoid, which is defined by the a thylakoid’s individual membrane. In the thylakoid space is a substance called lumen, and this mostly serves to provide structure and to build up a concentration gradient of protons during photosynthesis.
What is the granum?
A granum is a coin-shaped stack of thylakoids, which are the membrane-like structures found inside the chloroplasts of plant cells.
What is chlorophyll?
A green pigment, present in all green plants and in cyanobacteria, which is responsible for the absorption of light to provide energy for photosynthesis
What is the photosynthetic equation?
6CO2 + 6H2O + LIGHT ENERGY > C6H12O6 + 6O2
What is the simplest form of the photosynthetic equation?
CO2 + H2O > [CH2O] + O2, the brackets indicate CH2O is not an actual sugar but represents the general formula for a carbohydrate.
What is the O2 given of by plants derived from?
H2O not CO2
Is photosynthesis an exothermic or endothermic reaction?
An endothermic reaction because the electrons increase in potential energy as they move from water to sugar. This required energy is provided by light.
Is photosynthesis comprised of one process of two?
Two each with multiple steps
What are the two stages of photosynthesis known as?
The light reactions and the calvin cycle.
What occurs during the light reactions stage of photosynthesis?
This stage is the steps of photosynthesis in which converts solar energy to chemical energy. Water is split allowing a source of electrons and protons (Hydrogen ions) and giving of O2 as a by product. The light absorbed by the chlorophyll drives a transfer of the electrons and hydrogen ions from water to NADP+ where they are temporarily stored. This reduces NADP+ to NADPH. The light reactions also generate ATP to power the addition of a phosphate group to ADP
What occurs during the calvin cycle stage of photosynthesis?
The cycle begins with incorporating CO2 from the air into organic molecules already present in the chloroplast (Carbon Fixation). The calvin cycle then reduces the fixed carbon to carbohydrate by the addition of electrons and chemical energy. The reducing power is provided by NADPH (acquired in light reactions). Chemical energy is also provided by the ATP produced in light reactions. This then produces the sugar
What is photophosphorylation?
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation
What is Carbon fixation?
Carbon fixation or сarbon assimilation is the conversion process of inorganic carbon to organic compounds by living organisms. The most prominent example is photosynthesis.
What are the thylakoids the site of, during photosynthesis?
The sites of the light reactions
What is the stroma the site of during photosynthesis?
The calvin cycle
What is the energy of light?
Electromagnetic energy, also called electromagnetic radiation
What is the electromagnetic spectrum?
The entire range of radiation is known as the electromagnetic spectrum.
What is visible light?
The segment most important to life is the narrow band from about 380 nm to 750 nm in wavelength. This radiation is known as visible light because it can be detected as various colors by the human eye.
What are photons?
a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass. The shorter the wavelength, the greater the energy of each photon of that light. Thus, a photon of violet light packs nearly twice as much energy as a photon of red light
When light meets matter what 3 things can happen?
it may be reflected, transmitted, or absorbed.
What are pigments?
Substances that can absorb visible light. Different pigments absorb light of different wave- lengths, and the wavelengths that are absorbed disappear. the color we see is the color most reflected or transmitted by the pigment. (If a pigment absorbs all wavelengths, it appears black.)
Why do plants appear green?
We see green when we look at a leaf because chlorophyll absorbs violet-blue and red light while transmitting and reflecting green light
What does a spectrophotometer do?
It can measure the ability of a pigment to absorb various wavelengths of light. This machine directs beams of light of different wavelengths through a solution of the pigment and measures the fraction of the light transmit- ted at each wavelength. A graph plotting a pigment’s light absorption versus wavelength is called an absorption spectrum.
What is : chlorophyll a?
The key light-capturing pigment that participates directly in the light reactions; It absorbs most energy from wavelengths of violet-blue and orange-red light. It also reflects green-yellow light, and as such contributes to the observed green color of most plants.
What is : chlorophyll b?
Chlorophyll b is a form of chlorophyll. Chlorophyll b helps in photosynthesis by absorbing light energy. It is more soluble than chlorophyll a in polar solvents because of its carbonyl group. Its color is green, and it primarily absorbs blue light
What are carotenoids?
any of a class of mainly yellow, orange, or red fat-soluble pigments, including carotene, which give colour to plant parts such as ripe tomatoes and autumn leaves. they absorb violet and blue-green light
What is the action spectrum for photosynthesis?
This profiles the relative effectiveness of different wavelengths of radiation in driving the process. An action spectrum is prepared by illuminating chloroplasts with light of different colors and then plotting wavelength against some measure of photosynthetic rate, such as CO2 consumption or O2 release.
What is the difference between chlorophyll a and b?
A slight structural difference between them is enough to cause the two pigments to absorb at slightly different wavelengths in the red and blue parts of the spectrum. As a result, chlorophyll a appears blue green and chlorophyll b olive green under visible light.
What is an important function of some carotenoids?
Photoprotection: These compounds absorb and dissipate excessive light energy that would otherwise damage chlorophyll or interact with oxygen, forming reactive oxidative molecules that are dangerous to the cell. Carrots, known for aiding night vision, due to being rich in carotenoids
What exactly happens when chlorophyll and other pigments absorb light?
When a molecule absorbs a photon of light, one of the molecule’s electrons is elevated to an orbital where it has more potential energy. When the electron is in its normal orbital, the pigment molecule is said to be in its ground state. Absorption of a photon boosts an electron to an orbital of higher energy, and the pigment molecule is then said to be in an excited state. The only photons absorbed are those whose energy is exactly equal to the energy difference between the ground state and an excited state, and this energy difference varies Thus, a particular compound absorbs only photons corresponding to specific wavelengths, which is why each pigment has a unique absorption spectrum.
Why are white cars the coolest on a hot sunny day?
White cars are coolest because their paint reflects all wave- lengths of visible light.
In isolation, some pigments, including chlorophyll, emit light as well as heat after absorbing photons. As excited electrons fall back to the ground state, photons are given off. What is the afterglow called?
Florescence.
What are photosystems?
Photosystems are functional and structural units of protein complexes involved in photosynthesis that together carry out the primary photochemistry of photosynthesis: Photosystems are found in the thylakoid membranes. A photosystem is composed of a reaction-center complex surrounded by several light-harvesting complexes.
What is the reaction-center complex?
An organized association of proteins holding a special pair of chlorophyll a molecules and a primary electron acceptor.
What does a light-harvesting complex consist of?
Consists of various pigment molecules (which may include chlorophyll a, chlorophyll b, and multiple carotenoids) bound to proteins. The number and variety of pigment molecules enable a photosystem to harvest light over a larger surface area and a larger portion of the spectrum than could any single pigment molecule alone.
How does the photosystem work?
When a pigment molecule absorbs a photon, the energy is transferred from pigment molecule to pigment molecule within a light-harvesting complex, like a human “wave” at a sports arena, until it is passed to the pair of chlorophyll a molecules in the reaction-center complex. The pair of chlorophyll a molecules in the reaction-center complex are special because their molecular environment—their location and the other molecules with which they are associated—enables them to use the energy from light not only to boost one of their electrons to a higher energy level, but also to transfer it to a different molecule—the primary electron acceptor, which is a molecule capable of accepting electrons and becoming reduced. The transfer of an electron from the reaction- center chlorophyll a pair to the primary electron acceptor is the first step of the light reactions.
The thylakoid membrane is populated by two types of photosystems called what?
photosystem II (PS II) and photosystem I (PS I)
