1.1 and 1.2: Photosynthesis

• Carbon dioxide (CO2) enters the carbon cycle when it is released into the air by respiration or combustion.
• Plants utilize water (from the soil), carbon dioxide (from the air), and energy (from sunlight) to photosynthesize.

  
• Write the word equation for photosynthesis

  water + carbon dioxide --> glucose + oxygen
• The energy in sunlight is captured by a green pigment called chlorophyll which is inside the chloroplast (inside the mesophyll cells)
• The plants use the energy to make the water and carbon dioxide combine in a chemical reaction. Two new substances are created: glucose and oxygen.
• Write the chemical equation for photosynthesis

  6H20 + 6CO2 --> C6H12O6 + 6O2
• What are the reactants in photosynthesis?


  Water and Carbon Dioxide
• Collecting the gas produced in Photosynthesis.

  
  

  By setting up the apparatus in a location receiving sunlight, the water plant undergoes photosynthesis, releasing oxygen gas. The gas collects in the test tube through displacement of water. The subsequent steps involve careful manipulation to isolate the gas and perform a qualitative test for oxygen using a glowing splint. The relighting of the splint when introduced to the gas confirms the presence of oxygen, highlighting the plant's role as an oxygen producer.

  
• Experiment: Investigating how light intensity affects the rate of photosynthesis:

  The predicted outcome suggests that as the distance between the lamp and the test tube increases, the rate of photosynthesis, indicated by the number of bubbles produced by the plant, will decrease.
• Experiment: Investigating how light intensity affects the rate of photosynthesis:

  An increase in light intensity enhances the rate of photosynthesis by providing more energy for the biochemical reactions that convert light energy into chemical energy in plants.
• Experiment: Investigating how light intensity affects the rate of photosynthesis:

  As the lamp is moved further away, the intensity of light reaching the plant diminishes, limiting the rate of photosynthesis.
• 1. Photosynthesis provides energy, in the form of chemical energy in nutrients, for all other organisms.
• Plants utilize sunlight energy to produce glucose and other carbohydrates, which contain a portion of the energy originally from sunlight.
• Energy captured by plants through photosynthesis forms the basis of food chains, where organisms obtain energy by consuming plants or other organisms.
• Photosynthesis is crucial for replenishing oxygen in the Earth's atmosphere, as oxygen is released as a byproduct during the process, contributing to approximately 20% of the air composition.
• Explain how the lizard relies on photosynthesis to provide it with energy.

  Relies on energy from the food chain
• Chlorophyll, located within chloroplasts in plant cells, captures energy from sunlight, facilitating the reaction between water and carbon dioxide during photosynthesis.
• Photosynthesis occurs primarily within chloroplasts, and not all plant cells possess chloroplasts, limiting their ability to photosynthesize.
• Leaves typically contain the highest concentration of chloroplasts in most plants, making them the primary site for photosynthesis.
• Within leaf cells, carbon dioxide and water undergo a reaction to produce carbohydrates and oxygen, effectively acting as carbohydrate factories within the plant.
• Plants store excess carbohydrates, produced during photosynthesis, as starch within chloroplasts, providing a reserve of energy for times of low sunlight or increased metabolic demand. Testing leaves for the presence of starch can indicate whether photosynthesis has occurred.
• Testing a leaf for starch:

  Boiling water is used to facilitate the initial step of leaf preparation. Boiling water can break cell membranes. When plant tissues are subjected to boiling water, the heat causes the water inside the cells to expand rapidly, leading to the rupture of cell membranes. This facilitates the removal of pigments.
• Testing a leaf for starch:

  Ethanol is used to extract pigments from the leaf, dissolving the green chlorophyll pigments, which results in a loss of green coloration, causing the leaf to become pale or colorless. The presence of starch can be detected more easily after removing chlorophyll because chlorophyll tends to mask the color change caused by iodine staining, which is commonly used to detect starch. By removing chlorophyll from the leaf, the green coloration is eliminated, allowing for a clearer observation of the blue-black color resulting from the reaction between iodine and starch.
• The dissolved green color from the leaf is observed in the ethanol, indicating the successful extraction of chlorophyll
• Starch is a carbohydrate that serves as a storage form of glucose produced during photosynthesis. By applying iodine solution to the leaf, the presence of starch is indicated by a blue-black color change. This color change occurs because iodine molecules interact with the starch molecules, forming a complex that reflects light differently, resulting in the characteristic blue-black coloration. Thus, the presence of a blue-black color after applying iodine solution indicates that photosynthesis has occurred in the leaf, leading to the production and accumulation of starch.
• How does the experiment involve the use of ethanol?

  a solvent to extract pigments
• Photosynthesis produces glucose, which is converted and stored as starch in plant cells. The presence of starch in the leaf indicates that the leaf is photosynthesizing.
• Photosynthesis occurs within chloroplasts, located in certain leaf cells. Chloroplasts are primarily found in the middle layers of the leaf, easily accessible to sunlight due to the leaf's thin structure. Water, essential for photosynthesis, is transported to leaf cells through veins.
• Similarly, carbon dioxide enters the leaf through tiny openings called stomata, diffusing through air spaces between cells. These processes ensure chloroplasts have access to the necessary water and carbon dioxide for photosynthesis.
• The stomata are tiny openings or pores found on the surface of leaves and stems of plants. Their primary role is to regulate gas exchange, including the uptake of carbon dioxide (CO2) for photosynthesis and the release of oxygen (O2) and water vapor (H2O) produced during photosynthesis and respiration.

  
• When the stomata are flaccid (closed), gas exchange is restricted, reducing the intake of carbon dioxide for photosynthesis and minimizing water loss through transpiration. This can occur in response to environmental factors such as low light intensity, high temperatures, or water stress.
• when the stomata are turgid (open), gas exchange is facilitated, allowing for the uptake of carbon dioxide and release of oxygen and water vapor. This occurs when the guard cells surrounding the stomatal pore become swollen with water, causing them to open. Stomatal opening is typically regulated by environmental cues such as light intensity, humidity, and carbon dioxide levels, as well as internal factors such as plant water status and hormonal signals.
• The palisade layer contains cells that do most of the photosynthesis.
• The spongy layer has lots of air spaces. The cells in the spongy layer do a small amount of photosynthesis.
• Magnesium is vital for chlorophyll synthesis, contributing to leaf greenness and efficient photosynthesis. Insufficient magnesium results in yellowing leaves and reduced photosynthetic activity.
• 1. Nitrate provides essential nitrogen atoms for carbohydrate conversion into proteins, crucial for cell formation and plant growth. Inadequate nitrogen leads to leaf death and stunted growth. Nitrogen is also necessary for chlorophyll production, further highlighting its importance in plant vitality.Proper mineral supplementation through fertilization ensures optimal plant health and productivity.
• Plants have different levels of organization:

  • Similar cells combine to form tissues
  • Different types of tissues combine to form organs
  • Multiple organs combine to form organ systems
• A leaf is an organ that, along with a stem and roots, forms an organ system responsible for the transport of substances around the plant
• Water for photosynthesis comes from the soil and is transported to the leaves by the roots and xylem
• The spongy mesophyll tissue in the leaf has air gaps between cells to allow for easy diffusion of gases