Plant Growth and Photosynthesis Quiz

Plant Growth Requirements

• Water is crucial for photosynthesis, nutrient transport, and maintaining turgor pressure.
• Sunlight provides the energy for photosynthesis.
• Carbon dioxide is necessary for photosynthesis.
• Nutrients (like nitrogen, phosphorus, potassium) are essential for various plant metabolic functions.
• Oxygen is needed for respiration and is a byproduct of photosynthesis.
• Soil provides structural support and essential nutrients.

Photosynthesis and Biochemical Reactions

• Photosynthesis converts light energy into chemical energy stored in glucose. This occurs within chloroplasts.
• The light-dependent reactions happen in the thylakoid membranes, using water and sunlight to produce ATP, NADPH, and oxygen.
• The Calvin Cycle (light-independent reactions) takes place in the stroma, converting carbon dioxide, ATP, and NADPH into glucose.
• Light is essential for the light-dependent reactions of photosynthesis.

Dehydration and Hydrolysis

• Dehydration synthesis joins molecules by removing water (building larger molecules from smaller ones). For example, joining two monosaccharides forms a disaccharide.
• Hydrolysis breaks down large molecules by adding water (breaking down molecules into smaller parts). For example, breaking a disaccharide into two monosaccharides.

Water and Biomolecules Structure and Properties

• Water (H₂O) has two hydrogen atoms covalently bonded to one oxygen atom—a bent structure.
• Covalent bonds hold hydrogen and oxygen together within a water molecule.
• Hydrogen bonds form between the hydrogen of one water molecule and the oxygen of another. Water's polarity stems from uneven charge distribution.
• Water is a polar molecule, dissolving many substances, making it a universal solvent. This polarity comes from the partial positive charge on hydrogen and partial negative charge on oxygen.
• Water exhibits cohesion (water sticking to itself) and adhesion (water sticking to other surfaces).
• Water has a high specific heat and a high heat of vaporization, meaning it absorbs and releases heat slowly.

Biomolecules and Their Functions

• Biomolecules include carbohydrates (energy), proteins (building/repairing, enzymes), lipids (energy storage, membranes), and nucleic acids (genetic information).
• Organic molecules contain carbon and hydrogen bonds (carbohydrates, proteins, lipids, nucleic acids). Inorganic molecules do not.
• Enzymes are biological catalysts that speed up reactions by lowering activation energy. They're specific to their substrates and function via a "lock and key" mechanism. Factors like temperature, pH, and substrate concentration affect enzyme activity.
• Plants store energy as starch, while animals store it as glycogen.

Photosynthesis: Key Structures and Processes

• Chlorophyll is the green pigment absorbing light energy.
• Chloroplasts are the sites of photosynthesis within plant cells.
• Thylakoids are the membrane-bound compartments within chloroplasts where light-dependent reactions occur.
• Grana (a single granum) are stacks of thylakoids.
• Stroma is the fluid within the chloroplast where the Calvin Cycle occurs.
• Stomata are pores on leaves for gas exchange (CO₂ in, O₂ out).
• ATP (adenosine triphosphate) stores energy in cells. ADP (adenosine diphosphate) results from the release of a phosphate group from ATP.
• The summary equation for photosynthesis: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.
• Factors affecting photosynthesis rate include light intensity, CO₂ levels, and temperature.

Respiration

• Heterotrophs depend on consuming other organisms for energy.
• Mitochondria are the "powerhouses" of cells, sites of cellular respiration.
• Plants and animals both perform cellular respiration.
• Aerobic respiration produces 36-38 ATP molecules per glucose molecule.
• Anaerobic respiration (fermentation) produces 2 ATP per glucose molecule; it includes lactic acid and alcoholic fermentation.
• Aerobic respiration requires glucose and oxygen, producing carbon dioxide, water, and ATP (36-38 ATP molecules per glucose molecule).
• Summary equation for aerobic respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 36-38 ATP.
• Factors affecting respiration rate are oxygen availability, glucose levels, and temperature.

Carbon Cycle

• The carbon cycle includes photosynthesis, cellular respiration, burning fossil fuels, forest fires, decomposition, and carbon absorption by oceans.
• Plants take in CO₂ through photosynthesis converting it to glucose. Organisms release CO₂ as they break down glucose for energy—cellular respiration. Burning fossil fuels, forest fires, and decomposition also release CO₂. Oceans absorb significant amounts of CO₂.
• The various processes involved show the continuous cycling of carbon in the environment.