Chapter 8 Flashcards
(32 cards)
What is photosynthesis?
The process whereby light energy is captured by plant, algal, or photosynthetic bacterial cells and is used to synthesize organic molecules from CO2 and H2O (or H2S).
What are the two stages of photosynthesis?
- Light reactions
2. Calvin cycle
Define light reactions:
The first of two stages in the process of photosynthesis. During the light reactions, photosystem II and photosystem I absorb light energy and produce ATP, NADPH, and O2.
Define the Calvin cycle:
The second stage in the process of photosynthesis. During this cycle, ATP is used as a source of energy, and NADPH is used as a source of high-energy electrons, driving the synthesis of carbohydrates using CO2.
What are heterotrophs?
Organisms that cannot produce their own organic molecules by using energy from inorganic sources or light; they must obtain one or more organic compounds from their environment.
What is an autotroph?
An organism that has metabolic pathways that use energy from either inorganic molecules or light to make organic molecules.
Who are heterotrophs?
Most species of bacteria and protists, as well as all species of fungi and animals
What is a photoautotroph?
An organism that is a type of autotroph that uses the energy from light to make organic molecules from inorganic sources.
What are the key components of the energy cycle in the biosphere?
Photosynthesis uses CO2, Light, and H2O to produce O2 and organic molecules. Organic molecules are broken down into CO2 and H2O via cellular respiration to supply energy in the form of ATP. O2 is reduced to H2O.
What is chlorophyll?
A photosynthetic green pigment is found in the chloroplasts of plants, algae, and some bacteria.
Define mesophyll:
The internal tissue of a plant leaf; the site of photosynthesis.
What is a thylakoid membrane?
A membrane within the inner membrane of a chloroplast that forms many flattened, fluid-filled tubules that enclose a single, convoluted compartment. It contains chlorophyll and is the site where the light-dependent reactions of photosynthesis occur.
Describe the area inside the inner membrane of a chloroplast?
The fluid-filled region between the thylakoid membrane and the inner membrane is called the stroma. The thylakoid membrane encompasses many thylakoids stacked on top of each other to form grana (singular, granum). Every thylakoid has an enclosed compartment called the thylakoid lumen.
Where do light reactions take place?
At the thylakoid membrane.
Where does the Calvin cycle occur?
In the stroma.
What are the three chemical products of light reactions?
O2, NADPH, and ATP
Define wavelength:
The distance from one peak to the next in a sound wave or light wave.
What is the electromagnetic spectrum?
All possible wavelengths of electromagnetic radiation, from relatively short wavelengths (gamma rays) to much longer wavelengths (radio waves).
What is a photon?
One of the discrete particles that make up light. A photon is massless and travels in a wavelike pattern. Each photon contains a specific amount of energy.
What wavelengths carry more energy?
Shorter wavelength radiation carriers more energy per unit of time than longer wavelength radiation.
What are the three things that can happen when light hits an object?
- Light passes through the object.
- The path of the light is redirected by the object.
- Light is absorbed by the object.
What does the term pigment mean?
A molecule that can absorb light energy.
What does it mean when light energy is absorbed?
Light energy in the visible spectrum can be absorbed by an atom when it boosts an electron to a higher energy level.
What is needed for an electron to be boosted to a higher energy level?
In order for an electron to absorb light energy, it must overcome the difference in energy between the orbital it is in and the orbital it is going to.
