Ch.10 Exam Flashcards
(36 cards)
Define autotroph.
Have the ability to make their own food via photosynthesis
How do plants take in atmospheric CO2? How do plants absorb water?
- They take it through openings in their leaves called stomata
- Water is absorbed through a plants roots
Define transpiration.
Water evaporates and it exits through the leaves, it sucks up more water into its roots
During transpiration, how does water travel through plants?
Travels using vascular cells of plants
(Not a question, just information!) Photosynthetic organisms use sunlight to oxidize water into oxygen, and reduce carbon dioxide into glucose. This is the opposite as cellular respiration, where oxygen is reduced into water, and glucose is oxidized to form carbon dioxide!
(Not a question, just information!) Electrons move from a ground state (low energy) to an excited state (high energy). These electrons are harnessed in a network of pigments, referred to as a photosystem.
Define the five characteristics and attributes of a chloroplast: chlorophyll, stroma, thylakoids, grana, and mesophyll cells.
- Contain light absorbing pigments called chlorophyll which is involved in converting solar energy (sunlight) into chemical energy (glucose)
- Inside chloroplasts is a viscous liquid called stroma. Many chemical reactions take place in the stroma.
- Chloroplasts contain folded interconnected membranous sacs called thylakoids.
- Thylakoids form stacks called grana.
- Chloroplasts are found in high concentrations in the mesophyll cells (middle tissue) of a leaf
Chloroplasts can be found in multiple types of plant tissues. Where are they most abundantly found?
In the leaves of plants
Name the type of cell that regulate the opening of a leaves’ stomata.
Guard cells
Summarize what occurs during the light reactions of photosynthesis.
- Energy from light splits water, and drives the synthesis of ATP & NADPH (electron carrier)
- Occurs on the thylakoid membranes
-Synthesis of ATP and acquisition of an e-
Summarize what occurs during the dark reactions of photosynthesis.
- ATP is energy required to synthesize sugar
- NADPH provides electrons to reduce CO2 into glucose
- Occurs in stroma
- Uses ATP and reduced CO2 to form glucose
Light consists of high-speed particles called ______? These high-speed particles are packets of what type of energy?
- Photons
- electromagnetic energy
What are the three pigments found in chloroplasts that absorb different wavelengths? Describe which colors each pigment absorbs and reflects.
- Chlorophyll a, chlorophyll b, & carotenoids
- Chlorophyll absorbs violet / blue and yellow / orange / red light and they reflect green light
- Carotenoids absorb violet / blue/ green, and reflect yellow/ orange / red wavelengths
Write out the chemical equation for the splitting of water.
2H2O —> 4H+ + 4e- + O2
Define photosystem. What is a pigment’s role in a photosystem, and how does it relate to an electron’s energy state?
- A photo system is a molecular light-capture device.
- A pigment, supported by other molecules, receives an energy boost by the impact of photons
- This energy is used to excite electron to a higher energy state (resonance)
Explain how energy is transferred through photosystem II, including the role of electrons.
- H2O is split in order for for e- to be utilized by chlorophyll. Sunlight striking the chlorophyll molecules in photo system transfers energy, which eventually is used to excite the electron. This energy transfer is known as resonance.
- When the energy reaches the electron at the reaction center chlorophylls (called P680 in Photosystem II) it is transferred to the primary electron acceptor and “trapped” in its high-energy state
- The trapped excited electron slowly returns to its ground state as it “falls” down an electron transport chain connecting Photosystem II to Photosystem I.
When is the potential energy of the excited electron converted to kinetic energy? What is this kinetic energy used for?
- The potential energy of the excited electron is converted to kinetic energy as it “falls” down the chain
- This kinetic energy is used to pump hydrogen ions (H+) across the thylakoid membrane against their concentration gradient
Define proton motive force.
The large concentration gradient of H+ on one side of the membrane results in high potential energy
In which membrane of the chloroplast is ATP synthase found?
Thylakoid membrane
(Not a question, just information!) The way ATP is created through chemiosmosis with ATP synthase is very, very similar to the way it works in cellular respiration. Hydrogen ions are
used by moving down a concentration gradient, through ATP synthase, synthesizing ATP by oxidative phosphorylation. Other than location, the main difference is then where the ATP goes.
Explain the electron’s travel and role in photosystem I.
- Sunlight is absorbed by chlorophyll molecules in Photosystem I, and it excites electrons to a higher energy state (resonance)
- When the electron at the reaction is energized at center chlorophylls (called P700 in Photosystem I) it is transferred to the primary electron acceptor and “trapped” in its high-energy state
- An electron has now been lost from a chlorophyll molecule of Photosystem I, which is replaced by an electron “falling” down the electron transport chain from Photosystem II)
What is the P number for the center chorophylls in photosystem I and II? (Hint: An example would be P320, replacing 320 with the correct number for each system.)
Photosystem I: P700
Photosystem II: P680
What specifically carries the high-energy electron from the end of photosystem I to the Calvin cycle?
- The primary electron acceptor loses the high energy electron to NADP+ forming NADPH
- The primary electron acceptor is oxidized
- NADP+ is reduced to NADPH
- NADPH carries the high-energy electron to the Calvin cycle
Explain the roles of the two electron transport chains working during the light reactions.
- Two electron transport chains act during the light reactions
- One of these provides a link between the two photo systems during which ATP is made.
- The second one produced NADPH, an energized molecules (carrying electrons) used in the dark reactions (Calvin cycle)
What products from the light reactions are utilized in the Calvin cycle (dark reactions)?
ATP and electrons from NADPH which were made available in the light reactions, are utilized in the Calvin cycle (or dark reactions).
