Photosynthesis and Respiration Flashcards
Describe photosynthesis
Photosynthesis is the fundamental biological process through which plants, algae, and some bacteria convert light energy into chemical energy. This process is crucial for sustaining life on Earth as it produces oxygen and serves as the foundation of food chains.
Here is a detailed breakdown of the process:
Chlorophyll Absorption: Photosynthesis primarily occurs in specialized organelles within plant cells called chloroplasts. Chloroplasts contain a green pigment called chlorophyll, which absorbs light energy, particularly in the red and blue regions of the electromagnetic spectrum.
Light-Dependent Reactions (Light Reactions):
Light Absorption: Chlorophyll molecules absorb photons (light particles) and pass the energy through a series of pigment molecules. This energy excites electrons, leading to the production of high-energy molecules.
Water Splitting (Photolysis): Water molecules are split into oxygen, protons (H⁺ ions), and electrons. This process releases oxygen as a byproduct.
ATP and NADPH Formation: The energy from the excited electrons is used to generate two crucial energy-carrying molecules: ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate).
Calvin Cycle (Dark Reactions or Carbon Fixation):
Carbon Fixation: In this stage, carbon dioxide from the atmosphere is incorporated into organic molecules. This is facilitated by an enzyme called ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO).
Reduction Phase: ATP and NADPH produced in the light-dependent reactions are used to convert carbon dioxide into glucose and other carbohydrates.
Regeneration of RuBP: A portion of the carbohydrates formed is used to regenerate the initial molecule, ribulose-1,5-bisphosphate (RuBP), allowing the cycle to continue.
Glucose and Oxygen Production: The end products of photosynthesis are glucose (a sugar used for energy) and oxygen. Glucose can be stored by the plant for later use or broken down in cellular respiration to release energy.
In summary, photosynthesis is a complex biochemical process that harnesses light energy to convert carbon dioxide and water into glucose and oxygen. It is a critical process for maintaining oxygen levels in the atmosphere and providing the foundation of the food web, as it is the primary source of energy for most ecosystems.
Describe the law of limiting factors
The law of limiting factors, also known as Liebig’s law of the minimum, is a principle in ecology and biology that describes how the growth, development, and overall performance of an organism or a population are limited by the factor that is in the shortest supply or is least available relative to the organism’s needs. This concept was formulated by the German chemist and agricultural scientist Justus von Liebig in the 19th century.
The law of limiting factors can be summarized as follows:
Essential Factors: Organisms require a variety of factors, such as nutrients, water, light, temperature, and other environmental conditions, for their growth and survival.
Limiting Factor: The growth and development of an organism or a population will be primarily determined by the factor that is most scarce or limiting in its availability. Even if all other factors are in optimal conditions, if one essential factor is insufficient, it will restrict growth.
Bottleneck Effect: This principle can be likened to a bottleneck. Imagine a bottle being filled with different liquids of varying quantities. The height the liquid reaches in the bottle is determined by the shortest liquid supply. In the same way, the growth of an organism or a population is limited by the factor that is in the shortest supply.
Optimal Growth: To achieve optimal growth and performance, all necessary factors must be available in sufficient quantities. If one or more factors are deficient, it will hinder the organism’s ability to thrive.
Examples of the law of limiting factors in practice include:
In plant growth, if all conditions are suitable except for the availability of water, water becomes the limiting factor.
In agriculture, if a crop receives adequate sunlight and nutrients but is limited by the availability of essential minerals like nitrogen or phosphorus in the soil, then those minerals are the limiting factors.
In aquatic ecosystems, the growth of phytoplankton can be limited by the availability of nutrients like nitrogen or phosphorus in the water.
Understanding the law of limiting factors is crucial in various fields, including agriculture, ecology, and environmental science, as it helps researchers and practitioners identify and address the factors that most significantly influence the growth and well-being of organisms and populations, enabling more effective management and conservation efforts.
Steps of transpiration
1-Water is passively transported into the roots and then into the xylem. 2-The forces of cohesion and adhesion cause the water molecules to form a column in the xylem. 3- Water moves from the xylem into the mesophyll cells, evaporates from their surfaces and leaves the plant by diffusion through the stomata.
What is the process of respiration
The process of respiration in plants is important because it produces the energy molecule, ATP, needed by the plant for reproduction and survival. Respiration breaks down the glucose a plant produces during photosynthesis to form ATP.
