Photosynthesis Homework 3 Answer Key unlocks the mysteries of plant life, providing a comprehensive guide to the essential processes that sustain our planet. Delve into the intricate workings of photosynthesis, uncovering the vital role it plays in the delicate balance of Earth’s ecosystems.
Through detailed explanations and engaging examples, this guide empowers students to grasp the significance of photosynthesis, its impact on our environment, and its fundamental role in the survival of all living organisms.
Photosynthesis Overview
Photosynthesis is the process by which plants and other organisms use sunlight to convert carbon dioxide and water into oxygen and energy in the form of sugar.
Photosynthesis is essential for life on Earth. It provides the oxygen we breathe and the food we eat. It also helps to regulate the Earth’s climate by absorbing carbon dioxide from the atmosphere.
The Role of Sunlight, Carbon Dioxide, and Water in Photosynthesis, Photosynthesis homework 3 answer key
Sunlight is the energy source for photosynthesis. Carbon dioxide is the raw material that is converted into sugar. Water is used to split the carbon dioxide molecules and to provide the hydrogen atoms that are needed to form sugar.
The overall equation for photosynthesis is:
CO2+ 6H 2O + light energy → C 6H 12O 6+ 6O 2
Light-Dependent Reactions
The light-dependent reactions of photosynthesis are a series of chemical reactions that use light energy to produce ATP and NADPH. These molecules are then used in the light-independent reactions to convert carbon dioxide and water into glucose.
Role of Chlorophyll and Other Pigments
Chlorophyll is a green pigment that absorbs light energy from the sun. This energy is then used to excite electrons, which are then transferred to an electron acceptor. The electron acceptor then passes the electrons to a series of other electron carriers, which eventually leads to the production of ATP and NADPH.
Production of ATP and NADPH
The light-dependent reactions of photosynthesis produce ATP and NADPH through a process called photophosphorylation. Photophosphorylation is the process of using light energy to add a phosphate group to ADP to form ATP, or to NADP+ to form NADPH.
The light-dependent reactions of photosynthesis are essential for the production of glucose. Glucose is the main source of energy for most organisms, and it is used to power all of the activities of life.
Calvin Cycle (Light-Independent Reactions)
The Calvin cycle, also known as the light-independent reactions, is a series of chemical reactions that occur in the stroma of chloroplasts. These reactions use the energy stored in ATP and NADPH from the light-dependent reactions to convert carbon dioxide into glucose.
The Calvin cycle can be divided into three main stages:
Carbon Dioxide Fixation
The first stage of the Calvin cycle is carbon dioxide fixation. In this stage, carbon dioxide from the atmosphere is combined with a molecule of ribulose 1,5-bisphosphate (RuBP) to form two molecules of 3-phosphoglycerate (3-PGA).
Reduction
The second stage of the Calvin cycle is reduction. In this stage, the 3-PGA molecules are reduced to glyceraldehyde 3-phosphate (G3P) using ATP and NADPH from the light-dependent reactions.
Regeneration
The third stage of the Calvin cycle is regeneration. In this stage, one of the G3P molecules is used to regenerate RuBP, which can then be used to fix another molecule of carbon dioxide. The other G3P molecule is used to synthesize glucose.
| Reaction | Enzyme |
|---|---|
| Carbon dioxide fixation | Rubisco |
| Reduction | Glyceraldehyde 3-phosphate dehydrogenase |
| Regeneration | Fructose 1,6-bisphosphatase |
Factors Affecting Photosynthesis
The rate of photosynthesis is influenced by several environmental factors, including light intensity, temperature, carbon dioxide concentration, and water availability. These factors affect the efficiency of photosynthesis by influencing the rate of the light-dependent and light-independent reactions.
Light Intensity
Light intensity has a direct effect on the rate of photosynthesis. As light intensity increases, the rate of photosynthesis also increases until a plateau is reached. This is because light energy is required for the light-dependent reactions, which produce ATP and NADPH.
When light intensity is low, the rate of photosynthesis is limited by the availability of light energy.
Temperature
Temperature also affects the rate of photosynthesis. The optimal temperature for photosynthesis is around 25°C (77°F). When the temperature is too low, the rate of photosynthesis decreases because the enzymes involved in the process are not active. When the temperature is too high, the rate of photosynthesis also decreases because the enzymes are denatured.
Carbon Dioxide Concentration
Carbon dioxide concentration is another important factor that affects the rate of photosynthesis. The rate of photosynthesis increases as the concentration of carbon dioxide in the atmosphere increases. This is because carbon dioxide is a reactant in the light-independent reactions, which produce glucose.
Water Availability
Water availability is also essential for photosynthesis. Water is used in the light-dependent reactions to produce oxygen. When water is not available, the rate of photosynthesis decreases.
| Factor | Effect on Photosynthesis |
|---|---|
| Light Intensity | Increases the rate of photosynthesis |
| Temperature | Optimal temperature is around 25°C (77°F) |
| Carbon Dioxide Concentration | Increases the rate of photosynthesis |
| Water Availability | Essential for photosynthesis |
Importance of Photosynthesis
Photosynthesis is a vital process that underpins the existence of life on Earth. It is the primary mechanism by which energy from the sun is converted into chemical energy, stored in the form of glucose. This energy is then utilized by all living organisms for sustenance and growth.
Ecological Importance
Photosynthesis plays a crucial role in maintaining the Earth’s ecological balance. It is the foundation of food chains and food webs, as plants produce the organic matter that serves as sustenance for herbivores, which in turn are consumed by carnivores.
Additionally, photosynthesis generates oxygen as a byproduct, which is essential for respiration in all aerobic organisms.
Economic Importance
Photosynthesis has immense economic significance. It provides the raw materials for agriculture, forestry, and other industries. Plants are the source of food, fiber, timber, and various pharmaceutical products. The oxygen produced by photosynthesis is vital for industrial processes, such as combustion and manufacturing.
Carbon Cycle and Climate Regulation
Photosynthesis is integral to the carbon cycle, the process by which carbon dioxide is exchanged between the atmosphere and living organisms. Plants absorb carbon dioxide during photosynthesis, which helps regulate atmospheric carbon dioxide levels and mitigate climate change. Additionally, forests and other plant communities serve as carbon sinks, storing vast amounts of carbon and contributing to climate stability.
FAQ Summary: Photosynthesis Homework 3 Answer Key
What is the primary function of photosynthesis?
Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen, providing the foundation for the food chain and releasing oxygen into the atmosphere.
What are the two main stages of photosynthesis?
The light-dependent reactions capture light energy and produce ATP and NADPH, while the Calvin cycle uses these energy carriers to fix carbon dioxide into glucose.
How does photosynthesis contribute to the carbon cycle?
Photosynthesis removes carbon dioxide from the atmosphere and incorporates it into plant biomass, regulating the Earth’s climate and maintaining the balance of atmospheric gases.
