Biology CSF Chapter 8 HW

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

- H+ ions are used to help produce the energy carriers, ATP and NADPH - Excited electrons help move H+ ions to create a concentration gradient - Electrons on special chlorophyll molecules gain energy from light

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

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

Why do most plant leaves appear green?

- Pigments in plant cells absorb blue and red light, but much of the green light is reflected.

Which of the following scenarios is a direct effect of the absence of carbon dioxide during photosynthesis?

- The carbon fixation stage of the Calvin cycle would be unable to synthesize the sugar 3-PGA

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 chloroplasts of plant cells - generates sugars from the energy contained in sunlight - cannot convert sunlight energy to sugars without the direct input of carbon dioxide

Which characteristics describe characteristics of stomata in plants?

- permit carbon dioxide to enter and oxygen to escape from a plant - are openings into a plant that are surrounded by guard cells

Which statement describes the function of photosynthesis pigments in leaves?

- they capture light energy and remove electrons from a donor

Label components of a chloroplast: Select the component of chloroplast that is the site of light-dependent reactions...

.... thykaloids

Classify each description as applying to either autotrophs or heterotrophs.

Autotrophs: - producers - many use photosynthesis to produce organic compounds - use inorganic materials to produce energy - make their own food Heterotrophs: - consumers - unable to produce organic compounds from inorganic materials - depend on other organisms for energy - cannot make their own food

The light-independent reactions of photosynthesis, also known as 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 used and regenerated within the Calvin cycle.

Molecules brought in and used in the Calvin Cycle: - carbon dioxide - NADPH Molecules produced during the Calvin cycle that leave the cycle: - NADP+ - a few of the glyceraldehyde 3-phosphate (G3P) Molecules used and regenerated within the Calvin cycle: - Ribulose biphosphate (RuBP) - most of the glyceraldehyde 3-phosphate (G3P)

What is needed for the light-dependent reactions of photosynthesis to take place? What is produced during the light dependent reactions?

Needed for light-dependent reactions: -Light -Water -Chlorophyll Produced by light dependent reactions: - energy-rich ATP and NADPH

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.

Photosynthesis II: - The Hydrogen atoms from water molecules are split, producing H+ and replacement electrons for chlorophyll molecules - The energized electrons leaving this photosystem help pump H+ ions onto the thykaloid so that they can be used in ATP production Similarities: - Light energy is used to excite an electron on specialized chloophyll molecules Photosynthesis I: - Electrons from the electron transport chain are used to replace electrons lost from chlorophyll molecules - The energized electrons are used to form NADPH after leaving the photosystem

Classify each of the characteristics below as being exclusive to photosynthesis, exclusive to cellular respiration, or shared by both photosynthesis and cellular respiration.

Photosynthesis: - occurs in chloroplasts of plant cells - requires sunlight to proceed - synthesizes carbohydrates to store energy Cellular Respiration: - releases carbon dioxide (CO2) - Occurs in both plants and animals Both photosynthesis and cellular respiration: - generates ATP - generates energy ising a proton (H+) gradient - required an electron transport chain - occurs in plants

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