Unit 5: Cell Energy and Plant Transport Study Guide

Comprehensive vocabulary flashcards covering Unit 5: Cell Energy (Photosynthesis, Cellular Respiration, ATP, Fermentation, Carbon Cycle) and Plant Vascular Anatomy (Xylem and Phloem).

Photosynthesis

The cellular process that uses carbon dioxide ($\text{CO}_2$), water ($\text{H}_2\text{O}$), and light energy to produce glucose ($\text{C}_6\text{H}_{12}\text{O}_6$) and oxygen ($\text{O}_2$).

Photosynthesis Chemical Equation

$$6\text{CO}_2 + 6\text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$$

Chloroplast

The plant cell organelle in which photosynthesis takes place.

Stomata

Microscopic openings in leaves that allow carbon dioxide to enter and oxygen and water vapor to exit.

Guard Cells

Specialized cells that regulate the opening and closing of stomata.

Palisade Mesophyll Layer

The specific leaf layer containing abundant chloroplasts where the majority of photosynthesis occurs.

Chlorophyll

The primary green photosynthetic pigment that absorbs light energy (mainly red and blue wavelengths) and reflects green light.

Light-Dependent Reactions

Photosynthetic reactions that occur in the thylakoid membranes, utilizing sunlight and $\text{H}_2\text{O}$ to produce $\text{O}_2$, $\text{ATP}$, and $\text{NADPH}$.

Calvin Cycle (Light-Independent Reaction)

Photosynthetic reactions occurring in the stroma that utilize $\text{CO}_2$, $\text{ATP}$, and $\text{NADPH}$ to synthesize glucose ($\text{C}_6\text{H}_{12}\text{O}_6$).

Thylakoid

Flattened membrane sacs inside the chloroplast where the light-dependent reactions of photosynthesis take place.

Stroma

The fluid-filled interior space of the chloroplast surrounding the thylakoids where the light-independent reactions (Calvin cycle) occur.

Xylem

Vascular tissue situated on the inside of stem bundles that transports water and minerals upward in one direction from roots to leaves; composed of dead, hollow cells forming tubes with thick cell walls that provide structural support.

Phloem

Vascular tissue situated on the outside of stem bundles that transports glucose (sugars) made during photosynthesis in both directions (up and down) to roots, stems, leaves, and fruits; composed of living cells called sieve tube elements and companion cells.

Sieve Tube Elements

Living cells in phloem that align end-to-end to form tubular conduits for moving glucose and sugars throughout the plant.

Companion Cells

Living nucleated cells alongside sieve tube elements in phloem that aid in sugar transport.

Leaf Vein

A vascular bundle within a plant leaf comprising both xylem and phloem.

Vascular Bundles (Plant Stem Cross-Section)

Arrangement of plant transport tissues in the stem where xylem is located on the inside and phloem is located on the outside.

Cellular Respiration

The metabolic process that breaks down glucose in the presence of oxygen to release usable cellular energy ($\text{ATP}$), yielding carbon dioxide ($\text{CO}_2$) and water ($\text{H}_2\text{O}$).

Cellular Respiration Chemical Equation

$$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy (ATP)}$$

Glycolysis

The initial anaerobic stage of cellular respiration occurring in the cytoplasm that splits glucose into 2 pyruvic acid (pyruvate) molecules with a net gain of $2\text{ ATP}$.

Aerobic Respiration

Oxygen-dependent cellular respiration occurring in the mitochondria, comprising the Krebs cycle and electron transport chain, which yields approximately $36\text{--}38\text{ ATP}$ (or $30\text{--}32\text{ ATP}$ in eukaryotic cells) per glucose molecule.

Mitochondria

The eukaryotic organelles where the aerobic stages of cellular respiration take place to produce water, carbon dioxide, and the majority of cellular $\text{ATP}$.

Anaerobic Respiration (Fermentation)

A pathway that occurs without oxygen to regenerate reactants so glycolysis can continue, producing a net yield of only $2\text{ ATP}$ per glucose.

Lactic Acid Fermentation

A type of anaerobic respiration occurring in human muscle cells during intense oxygen deficiency and in some microorganisms, yielding lactate (lactic acid) and $2\text{ net ATP}$.

Alcoholic Fermentation

A type of anaerobic respiration carried out by yeast and some microorganisms that converts pyruvate into ethyl alcohol (ethanol) and carbon dioxide ($\text{CO}_2$).

Adenosine Triphosphate (ATP)

A nucleotide molecule composed of adenine, a ribose sugar, and three phosphate groups that serves as the immediate energy currency for cellular activities.

ATP-ADP Cycle

The mechanism of energy transfer wherein removing the third (terminal) phosphate group from ATP releases energy and forms ADP and inorganic phosphate ($\text{P}_i$), while reattaching a phosphate requires energy: $\text{ADP} + \text{P}_i + \text{energy} \rightarrow \text{ATP}$.

The Sun

The ultimate source of energy for most living organisms and food chains on Earth.

Autotroph

An organism, such as grass or algae, that produces its own organic food molecules from inorganic raw materials.

Heterotroph

An organism, such as a human or mushroom, that acquires organic energy and nutrients by consuming other organisms or organic matter.

Global Stewardship

Practices that protect the biosphere and lower atmospheric carbon levels, including conserving electricity, burning fewer fossil fuels, using alternative transportation, and protecting or planting trees.