Photosynthesis

What is photosynthesis?

• the biological process where sunlight triggers plants to use carbon dioxide and sugars to create water and oxygen.

• the biological process where plants absorb sunlight to directly produce oxygen

• the biological process whereby plants convert inorganic substances to organic substances using light energy trapped by chlorophyll

• Photosynthesis is the process in which plants transform light energy into heat energy for cellular respiration.

Draw a palisade cell

There are _____ reactions in photosynthesis the _______ and the ______

Which of the following is NOT an adaptation of the leaf for photosynthesis?

• elongated, tightly packed palisade cells with abundant chloroplasts

• waxy cuticle made of cutin

• Numerous stomata for maximum gas exchange and water absorption.

• irregular shaped spongy mesophyll cells

Which of the following statements is true about the light reaction?

• Chlorophyll absorbs light energy during the light reaction, which is used to directly bond hydrogen to carbon atoms.

• The light reaction traps sunlight in the chloroplasts and releases it slowly as heat energy to power the plant’s growth.

• Chlorophyll absorbs light energy to split water into hydrogen and oxygen

• Chlorophyll traps light energy to split water into hydrogen and oxygen

when the _____ cells are _____ the _____ opens

Which of the following does NOT happen to glucose after photosynthesis?

• It is stored in the chloroplast as starch granules indefinitely.

• It is converted into glycogen for long-term storage in the cell.

• it is converted to sucrose and transported to other parts of the plant

How do the essential components for photosynthesis reach the chloroplasts in plant cells?

• CO₂ diffuses into the leaf through the cuticle, then travels to the palisade cells for photosynthesis. Water moves up the xylem and directly into the chloroplasts for use. Light is absorbed by chloroplasts in all leaf cells.

• CO₂ enters through the stomata, moves through the mesophyll cells, and diffuses into the palisade cells. Water travels up the xylem and moves via osmosis into the palisade cells. Light enters through the leaf surface and is absorbed by chloroplasts in the palisade cells.

• CO₂ enters through the stomata, moves into the air spaces around the mesophyll cells, and directly enters the chloroplasts. Water enters the leaf through the stomata and is directly absorbed by the palisade cells. Light passes through the leaf surface to chloroplasts in all cells.

• CO₂ diffuses into the leaf through the epidermis and moves through the xylem into the palisade cells. Water travels into the root, moves up the phloem, and enters the chloroplasts. Light is absorbed by chloroplasts in all leaf tissues.

Which of the following statements best explains the synergistic roles of the upper epidermis, waxy cuticle, and palisade mesophyll cells in maximizing the efficiency of photosynthesis while minimizing water loss in a leaf?

• The upper epidermis, being transparent, allows light to reach the palisade mesophyll cells, but its tightly packed cells reduce the effective surface area for light absorption. The waxy cuticle on the leaf surface helps reduce water loss, but also prevents the diffusion of CO₂, thereby decreasing the rate of photosynthesis. The palisade mesophyll cells, rich in chloroplasts, compensate by using the limited light more efficiently.

• The upper epidermis, with its transparency and tight cellular arrangement, reduces the diffusion of CO₂ into the leaf, limiting photosynthetic efficiency. The waxy cuticle minimizes water loss, indirectly increasing photosynthetic output by concentrating internal CO₂ levels. The palisade mesophyll cells, located just beneath the epidermis, enhance light absorption through their high chloroplast content.

• The upper epidermis, being transparent, allows for maximum light transmission into the leaf, which is then absorbed by the palisade mesophyll cells. The waxy cuticle reduces water loss, ensuring that the leaf remains hydrated, while also preventing pathogen entry. This combination of factors maintains a balance between efficient light absorption and water retention, optimizing photosynthesis.

draw a spongy mesophyll cell