Sapling Biology Assignment 10

Choose all events that occur during the light-dependent reactions of photosynthesis.

-H+ ions are used to help produce the energy carriers, ATP and NADPH. - Electrons on special chlorophyll molecules gain energy from light. - A concentration gradient forms as excited electrons help move H+ ions.

Plants synthesize their own food in the form of sugars during the process of photosynthesis. Which of the following statements describe photosynthesis?

-Is a cellular process that occurs in the chloroplasts of plant cells - Converts carbon dioxide to sugars, releasing oxygen - Produces sugars for the plant using only the energy from sunlight

Complete the photosynthesis reactions by placing the following items as reactants, energy sources, or products of these reactions. Not all labels will be placed.

6CO2 + 6H2O = C6H12O6 + 6O2 Energy source: light

Classify each description as applying to either autotrophs or heterotrophs.

Autotrophs: -Use inorganic materials to produce energy - Make their own food - Producers - Many use photosynthesis to produce organic compounds Heterotrophs: - Unable to produce organic compounds from inorganic materials - Cannot make their own food - Depend on other organisms for energy - Consumers

Which statements apply only to C3, C4, or CAM photosynthesis? Which statement applies to all three types of photosynthesis?

C3: All the cells that have chloroplasts attach CO2 directly to ribulose bisphosphate to produce sugars. C4: One set of cells harvests CO2 and passes the carbon to another set of cells that builds sugars. CAM: Gas exchange happens at night when the stomata are open, whereas sugars are produced during the day. C3, C4, and CAM: Sugars are produced using CO2, H2O, and light energy.

During one of the three phases of the Calvin cycle, the carbon atoms from three CO2 molecules are incorporated into three five-carbon sugar molecules called ribulose bisphosphate (RuBP). This reaction forms an unstable six-carbon intermediate which immediately splits into two three-carbon sugar molecules called 3-phosphoglyceric acid (3PGA). In which phase of the Calvin cycle does this occur?

Carbon fixation

Consider what happens to energy in photosynthesis. How does this differ from what happens to energy in cellular respiration?

In photosynthesis, energy is captured by light, whereas in cellular respiration energy is transferred from storage molecules to ATP.

Arrange the events of the light-dependent reactions of photosynthesis in the order that they occur.

Initial event -Electrons on specific chlorophyll molecules are excited by light. - Chlorophyll molecules release electrons that travel down an electron transport chain. - Hydrogen ions are pumped into the interior of the thylakoid. - H+ ions flow out of the thylakoid through an enzyme channel. - ATP and NADPH are produced. Final event

Which statements describe the light-dependent reactions of photosynthesis, which describe the Calvin cycle (light-independent reactions of photosynthesis), and which describe both?

Light-dependent reaction: -Require water -Use chlorophyll to capture light energy -Generate oxygen gas -Synthesize ATP and NADPH Calvin cycle: -Use CO2 -Produce sugars -Need ribulose bisphosphate Both: -Take place in the chloroplasts of plants

The events below are parts of the overall process of photosynthesis. For each event, identify the chloroplast structure that facilitates the event. Each structure may be used once, more than once, or not at all.

Light-dependent reactions: Thylakoid membrane CO2-dependent reactions: Stroma Calvin cycle: Stroma ATP production: Thylakoid membrane

The light-dependent reactions of photosynthesis, also called the Calvin cycle, use and produce a variety of molecules. Sort the molecules below into three categories, molecules brought in and used in the Calvin cycle, molecules produced during the Calvin cycle that leave the cycle, and molecules made in the cytoplasm from the products of the Calvin cycle.

Molecules brought in and used in the Calvin cycle: -CO2 from outside the cell -Molecules carrying energy from the light-dependent reactions Molecules produced during the Calvin cycle that leave the cycle: -Energy-carrier molecules that have lost some energy\ -3-carbon molecules that store energy Molecules made in the cytoplasm from the products of the Calvin cycle: -Organic molecules such as glucose

What is needed for the light-dependent reactions of photosynthesis to take place? What is produced during the light-dependent reactions? Not all of the answer choices will be placed.

Needed for light-dependent reactions: -Light energy -H2O molecules - Chlorophyll Produced by light-dependent reactions: - High-energy NADPH and ATP

During one of the three phases of the Calvin cycle, six molecules of ATP and six molecules of NADPH transfer electrons to six three-carbon sugars known as 3-phosphoglyceric acid (3PGA). The transfer of electrons transforms the six 3PGA molecules into six molecules of a three-carbon sugar called glyceraldehyde-3-phosphate (G3P). In which phase of the Calvin cycle does this occur?

Reduction

During one of the three phases of the Calvin cycle, three molecules of ATP are used to catalyze the rearrangement of five three-carbon sugars, know as glyceraldehyde-3-phosphate (G3P), into three five-carbon sugars, know as ribulose bisphosphate (RuBP). One other molecule of G3P is exported to the cytoplasm to form glucose. In which phase of the Calvin cycle does this occur?

Regeneration

Sort the statements into those that describe similarities between the two photosystems in the light-dependent reactions of photosynthesis and those that are unique to each of the photosystems.

Similarities between the two photosystems: Light energy is used to excite an electron on specialized chlorophyll molecules. Unique to photosystem II: - The hydrogen atoms for water molecules are split, producing H+ and replacement electrons for chlorophyll molecules. - Energy from electrons excited in this photosystem is used to help pump H+ ions into the thylakoid for ATP production. Unique to photosystem I: - Replacement electrons for chlorophyll molecules come from the electron transport chain. - The energized electrons are used to form NADPH after leaving this photosystem.

Which statement accurately describes the Calvin cycle?

The Calvin cycle is a light-independent metabolic pathway occurring in the chloroplast stroma that converts carbon from carbon dioxide into sugar.

Which statement describes the function of photsynthetic pigments in leaves?

They capture light energy and remove electrons from a donor.

Label the components of a chloroplast.

Top 1. Double membrane 2. Granum 3. Thylakoid 4. Stroma Bottom

During the light-dependent reactions of photsynthesis, energy excites electrons in chlorophyll molecules, transforming the energy into chemical energy.

What provides the energy that excites the electrons in the chlorophyll molecules? Light What is the source of the electrons that replace the excited electrons lost from chlorophyll? Water