Chloroplasts and Photosynthesis Quiz

Chloroplasts and Photosynthesis

• In the light-independent stage, ATP and reduced NADP are used to reduce carbon dioxide and produce carbohydrates in the Calvin cycle.
• Chloroplasts, found in specific plant cells like palisade mesophyll and spongy mesophyll tissues in leaves, host both light-dependent and light-independent stages of photosynthesis.
• Each chloroplast contains an envelope of two membranes and a watery stroma with enzymes, ribosomes, DNA, and starch grains for carbohydrate storage.
• Inside chloroplasts, membranes called lamellae form fluid-filled sacs called thylakoid spaces, and stacks of thylakoids called grana, which hold carrier molecules and photosynthetic pigments like chlorophyll a and b, carotene, and xanthophyll.
• Chloroplast pigments absorb different wavelengths of light and drive photosynthesis; chlorophyll a absorbs violet, blue, and red light, while accessory pigments like chlorophyll b and carotenoids absorb other wavelengths.
• Carotenoids, including beta-carotene, give orange colors to fruits and vegetables and are revealed as fall colors when chlorophyll breaks down in autumn leaves.
• The majority of pigments in a chloroplast are chlorophyll a and b, which gives chloroplasts and leaves their green color, and absorb slightly different wavelengths of light.
• Pigments in thylakoid membranes are arranged in clusters called photosystems, with photosystem I absorbing mainly 700 nm light and photosystem II absorbing mainly 680 nm light.
• Photosystems contain chlorophyll a molecules and other pigments that channel energy to these chlorophyll a molecules, increasing the energy level of electrons to drive the light-dependent stage of photosynthesis.
• The electromagnetic spectrum ranges from short-wavelength gamma rays to long-wavelength radio waves, and photons of specific wavelengths are either reflected, transmitted, or absorbed by objects like leaves.
• The absorbed light energy can drive biological processes like photosynthesis, and chloroplasts contain a variety of pigment molecules that absorb different wavelengths of light.
• A practical application involves measuring the transpiration rate using a potometer.

Photosynthesis and Chloroplast Structure

• In the light-independent stage, ATP and NADP are used to reduce carbon dioxide and produce carbohydrates in the Calvin cycle.
• Chloroplasts, found in certain plant cells, are essential for both light-dependent and light-independent stages of photosynthesis.
• Each cell can contain multiple chloroplasts, located mainly in leaf tissues such as palisade mesophyll and spongy mesophyll.
• Chloroplasts have a stroma containing enzymes, ribosomes, DNA, and starch grains used for carbohydrate storage.
• Grana, stacks of thylakoids, contain membranes with carrier molecules and various photosynthetic pigments.
• Chlorophyll a and b are the main pigments in chloroplasts, absorbing different wavelengths of light for photosynthesis.
• Accessory pigments like carotenoids absorb additional wavelengths of light and give fruits and vegetables their color.
• Chlorophylls and accessory pigments collectively create the green color of chloroplasts and leaves.
• Photosystems in thylakoid membranes absorb light energy and channel it to a reaction center for the light-dependent stage of photosynthesis.
• Photosystem I absorbs light at 700 nm, while photosystem II absorbs light at 680 nm, both containing chlorophyll a molecules.
• The high-energy electrons from chlorophyll a drive the light-dependent stage of photosynthesis.
• The text also mentions a practical application, the measurement of transpiration rate using a potometer.

Photosynthesis and Chloroplast Structure

• In the light-independent stage, ATP and NADP are used to reduce carbon dioxide and produce carbohydrates in the Calvin cycle.
• Chloroplasts, found in certain plant cells, are essential for both light-dependent and light-independent stages of photosynthesis.
• Each cell can contain multiple chloroplasts, located mainly in leaf tissues such as palisade mesophyll and spongy mesophyll.
• Chloroplasts have a stroma containing enzymes, ribosomes, DNA, and starch grains used for carbohydrate storage.
• Grana, stacks of thylakoids, contain membranes with carrier molecules and various photosynthetic pigments.
• Chlorophyll a and b are the main pigments in chloroplasts, absorbing different wavelengths of light for photosynthesis.
• Accessory pigments like carotenoids absorb additional wavelengths of light and give fruits and vegetables their color.
• Chlorophylls and accessory pigments collectively create the green color of chloroplasts and leaves.
• Photosystems in thylakoid membranes absorb light energy and channel it to a reaction center for the light-dependent stage of photosynthesis.
• Photosystem I absorbs light at 700 nm, while photosystem II absorbs light at 680 nm, both containing chlorophyll a molecules.
• The high-energy electrons from chlorophyll a drive the light-dependent stage of photosynthesis.
• The text also mentions a practical application, the measurement of transpiration rate using a potometer.

Photosynthesis and the Calvin Cycle: Key Processes and Reactions

• Photosystem II captures energy from light and boosts electrons to the primary electron acceptor.
• Replacement electrons for photosystem II come from the splitting of water by an enzyme associated with photosystem II.
• Water splitting releases electrons to replace those lost by the reaction center chlorophylls and produces O2 and hydrogen ions.
• The energized electron from photosystem II travels through an electron transport chain (ETC) to generate a H+ gradient and ATP through chemiosmosis.
• Photosystem I absorbs light energy and passes it to a chlorophyll a molecule in the reaction center, energizing an electron.
• The energized electron from photosystem I is passed to a second ETC to generate NADPH.
• Cyclic and non-cyclic photophosphorylation are processes for ATP production using energy from light.
• Photosystem II includes a water-splitting enzyme that catalyzes the breakdown of water, producing O2 as a waste product.
• ATP and NADPH synthesized during the light reactions power the synthesis of glyceraldehyde-3-phosphate (G3P) from CO2 in the Calvin cycle.
• The Calvin cycle involves carbon fixation, the synthesis of G3P, and the regeneration of RuBP to continue the cycle.
• Carbon fixation in the Calvin cycle can be disrupted by photorespiration, a wasteful process reducing the rate of carbon fixation.
• The Calvin cycle is a metabolic pathway that converts CO2 into G3P using ATP and NADPH, and it begins and ends with the same five-carbon molecule, RuBP.