40 Questions
What is the primary function of the Calvin cycle in photosynthesis?
To reduce CO$_2$ to sugar using the chemical energy of ATP and NADPH
What is the role of the light reactions in photosynthesis?
To convert solar energy to the chemical energy of ATP and NADPH
In photosynthesis, what is the ultimate source of energy for converting CO$_2$ and H$_2$O into organic molecules and oxygen?
Sunlight
What is the significance of alternative mechanisms of carbon fixation in hot, arid climates?
They have evolved to enable photosynthesis in challenging environmental conditions
Where does the Calvin cycle occur in the chloroplast?
Stroma
What is the primary source of energy for the process of photosynthesis?
Light
What is the waste product released during photosynthesis?
Oxygen
Which molecule is reduced to carbohydrate during the Calvin cycle?
Carbon dioxide
What is the function of NADPH and ATP in photosynthesis?
Incorporate CO2 into organic molecules
Where do the light reactions occur in the chloroplast?
Thylakoids
What is the name of the process that involves the splitting of water and generation of NADPH and ATP?
Light reactions
What is the alternative name for the Calvin cycle?
Dark reactions
What is the primary product of the light reactions in photosynthesis?
Oxygen
What is the role of the chloroplast in photosynthesis?
Convert solar energy to chemical energy
What is the function of the thylakoids in photosynthesis?
Convert solar energy to chemical energy
What is the overall function of the light reactions and the Calvin cycle in photosynthesis?
Convert solar energy to chemical energy
What drives photosynthesis, ranging from 380 nm to 740 nm in wavelength?
Electromagnetic spectrum of white light
What does chlorophyll, the primary photosynthetic pigment, absorb?
Violet-blue and red light
What does an absorption spectrum represent?
How well a particular pigment absorbs different wavelengths of visible light
What do NADP+ and ADP molecules release during the light reactions of photosynthesis?
NADPH and ATP
What is the role of a spectrophotometer in photosynthesis research?
Measuring the relative amounts of light of different wavelengths absorbed and transmitted by a pigment solution
What is the function of the atmosphere in photosynthesis?
Acts as a selective window, allowing visible light to pass through and driving photosynthesis
What does the absorption spectra of chloroplast pigments help scientists understand?
The role of each pigment in a plant
What are the products released to the stroma during the light reactions of photosynthesis?
NADPH and ATP
What is the role of photons in light energy transmission?
Behaving like discrete particles
What is the primary function of the light reactions of photosynthesis?
Convert solar energy into the chemical energy of ATP and NADPH in chloroplasts
What do photosynthetic pigments absorb?
Visible light, with different pigments absorbing different wavelengths and reflecting or transmitting others
What is the outcome of the two stages of photosynthesis?
Depicted as metabolic modules that take in ingredients and produce products
What is the primary site of photosynthesis in a plant?
Leaves
How many chloroplasts are approximately found in a chunk of leaf with a 1 $mm^2$ top surface area?
Half a million
Where does CO2 enter the leaf and O2 exit from?
Stomata
How many chloroplasts are approximately found in each mesophyll cell?
30-40
Where does chlorophyll, the green pigment in leaves, reside?
Thylakoid membranes
What is the overall chemical change during photosynthesis?
The reverse of cellular respiration
What is the direct product of photosynthesis?
A three-carbon sugar
Where is the dense fluid called the stroma located within a chloroplast?
Between the two membranes
What do chloroplasts use as a source of electrons during photosynthesis?
Hydrogen atoms from water
What is the third membrane system made up of sacs within a chloroplast?
Thylakoids
What did scientists use as a tracer to confirm that plants split H2O as a source of electrons during photosynthesis?
Oxygen-18
What is the overall photosynthetic equation?
6 CO2 + 12 H2O + Light energy → C6H12O6 + 6 O2 + 6 H2O
Study Notes
Chloroplasts and Photosynthesis in Plants
- Chloroplasts are found in all green parts of a plant, with leaves being the primary sites of photosynthesis.
- A chunk of leaf with a 1 mm2 top surface area contains about half a million chloroplasts.
- CO2 enters the leaf and O2 exits through microscopic pores called stomata, while water is delivered to the leaves through veins.
- Each mesophyll cell contains about 30–40 chloroplasts, each measuring about 2–4 µm by 4–7 µm.
- A chloroplast has two membranes surrounding a dense fluid called the stroma, with a third membrane system made up of sacs called thylakoids.
- Chlorophyll, the green pigment in leaves, resides in the thylakoid membranes of the chloroplast.
- The overall photosynthetic equation has been known since the 1800s: 6 CO2 + 12 H2O + Light energy → C6H12O6 + 6 O2 + 6 H2O.
- The direct product of photosynthesis is actually a three-carbon sugar that can be used to make glucose.
- Both photosynthesis and cellular respiration occur in plant cells, but chloroplasts do not synthesize sugars by simply reversing the steps of respiration.
- The overall chemical change during photosynthesis is the reverse of the one that occurs during cellular respiration.
- Chloroplasts split water into hydrogen and oxygen atoms, and the O2 released during photosynthesis comes from water, not from CO2.
- Scientists confirmed the hypothesis that plants split H2O as a source of electrons from hydrogen atoms, releasing O2 as a by-product using oxygen-18 as a tracer.
Test your knowledge of chloroplasts and photosynthesis in plants with this quiz. Explore the structure of chloroplasts, the process of photosynthesis, and the role of chlorophyll in producing glucose and oxygen. Dive into the intricate details of how plants use water and carbon dioxide to create energy through this essential biological process.
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