37 Questions
What are the thylakoid membranes filled with?
Saclike chlorophyll-containing thylakoids
Which part of the chloroplast is responsible for the fluid portion outside the thylakoids?
Stroma
What is the main role of chlorophyll in photosynthesis?
Absorbing light and transferring energy to electrons
Grana are mainly stacks of what?
Thylakoids
Which molecules are built using the high-energy electrons provided by chlorophyll?
Sugar molecules from carbon dioxide and water
What are the main pigments involved in photosynthesis in green plants?
Chlorophyll a and Chlorophyll b
What is the role of NADP in photosynthesis?
It serves as an electron carrier.
In which part of the plant cell does photosynthesis occur?
Chloroplast
Which wavelengths of light are best absorbed by chlorophyll a?
Blue-violet
How do light-independent reactions in photosynthesis differ from light-dependent reactions?
Light-independent reactions do not require light.
Which product is directly generated by the light-dependent reactions of photosynthesis?
ATP
What makes up the visible spectrum that our eyes perceive as 'white' light?
A mixture of different wavelengths
Why do most leaves appear green in color?
Chlorophyll reflects green light.
What is the primary function of an electron carrier in plant cells?
To transport high-energy electrons
Which molecule acts as an electron carrier by accepting and holding two high-energy electrons and a hydrogen ion (H+)?
NADP+
In the analogy provided, what is used to represent NADP+?
A cooking pan
What happens when NADP+ accepts high-energy electrons and a hydrogen ion (H+)?
It is converted into NADPH
What is the role of NADPH in the chloroplast?
To carry high-energy electrons to chemical reactions
What is the initial source of high-energy electrons that NADP+ carries?
Chlorophyll absorption of light
Why do plant cells need electron carriers like NADP+?
To transport the energy to build sugars like glucose
What is NADP+ converted into after accepting high-energy electrons and a proton?
NADPH
What compounds produced in the light dependent reactions are utilized in the light independent reactions?
ATP and NADPH
In photosynthesis, where do the light independent reactions occur?
In the chloroplast stroma
What role does chlorophyll play in photosynthesis?
It absorbs light energy
Which molecule is directly involved in the creation of sugars during the light independent reactions?
Carbon dioxide
What is the primary function of NADPH in photosynthesis?
Carrying electrons
How does the light independent reaction differ from the light dependent reaction in terms of light requirement?
Light independent reactions do not require light
What process fixes carbon into sugar molecules during photosynthesis?
Calvin cycle
Which critical molecule is regenerated during the light independent reactions to continue the Calvin cycle?
RuBP
What is the main purpose of photosynthesis?
To convert water and carbon dioxide into high-energy sugars and oxygen
How is ATP generated during the light-dependent reactions of photosynthesis?
By adding a third phosphate to ADP using sunlight energy
During photosynthesis, what molecule acts as an electron carrier?
NADP+
What are the main products of photosynthesis?
Sugars and oxygen
Where do the light-dependent reactions of photosynthesis take place?
In the thylakoid membranes
What happens to the oxygen atoms from water molecules during the light-dependent reactions?
They are released as oxygen gas
What is the overall chemical equation for photosynthesis in symbols?
$6CO_2 + 6H_2O \xrightarrow{light} C_6H_{12}O_6 + 6O_2$
Why is Elodea a good subject for investigating the wavelengths of light used in photosynthesis?
It is an aquatic plant that can easily be observed
Study Notes
Photosynthesis: An Overview
- Photosynthesis is the process by which plants, and some other organisms, convert light energy from the sun into chemical energy in the form of organic compounds, such as glucose.
- This process is crucial for life on Earth, as it provides energy and organic compounds for plants and, indirectly, for animals that feed on plants.
Chlorophyll and Chloroplasts
- Chlorophyll: the green pigment found in plants that plays a crucial role in photosynthesis by absorbing light energy.
- Chloroplast: the organelle where photosynthesis takes place; it contains grana (stacks of thylakoid membranes) and stroma (the fluid portion outside of the thylakoids).
Light and Pigments
- Light energy from the sun reacts with Earth in the form of light energy, which is perceived as "white" light, comprising different wavelengths.
- Pigments: light-absorbing compounds that capture the energy of sunlight; the principal pigments in green plants are chlorophyll a and chlorophyll b.
- Chlorophyll a absorbs blue-violet and a region of the visible spectrum, while chlorophyll b absorbs blue-violet and a region of the visible spectrum, but not red.
Energy Collection and Electron Carriers
- Chlorophyll absorbs light energy, transferring it to its own electrons, which become high-energy electrons.
- These high-energy electrons are then carried by electron carriers, such as NADP (nicotinamide adenine dinucleotide phosphate), to other molecules.
- NADP accepts and holds two high-energy electrons, along with a hydrogen ion (H+), converting NADP+ into NADPH.
Light-Dependent and Light-Independent Reactions
- Light-dependent reactions: the reactions in photosynthesis that require light energy, taking place in thylakoid membranes, producing ATP and NADPH.
- Light-independent reactions: the reactions in photosynthesis that do not require light energy, using ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into glucose.
Stages of Photosynthesis
- The overall equation for photosynthesis: 6CO2 + 6H2O + light → C6H12O6 (glucose) + 6O2
- Plants absorb carbon dioxide from the atmosphere and complete the process of photosynthesis to fix carbon-containing sugars.
This quiz covers the basics of photosynthesis, including the role of pigments, electron carriers, and the products of photosynthesis.
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