Science Unit 4

• Aerobic respiration takes place when oxygen is available.
• Anaerobic respiration takes place when oxygen is not available.
• Cellular respiration uses glucose and oxygen (reactants) to produce water, carbon dioxide (products) and ATP energy.
• ATP is a chemical found in most living cells and is used for energy.
• Waxy Cuticle is a waxy waterproof layer which reduces the rate of water loss from the leaf surface (water loss), it is transparent to allow light through the leaf.
• Palisade layer cells are where light absorption happens, where most of the photosynthesis occurs in the leaf.
• Spongy layer cells are where transpiration occurs, allows for the interchange of gases (CO2) that are needed for photosynthesis.
• Veins (xylem and phloem) are tissues to transport water, nutrients and minerals through the plant.
• Xylem transports water and mineral salts from the roots up to other parts of the plant.

  Phloem transports sucrose and amino acids from the leaves and other parts of the plant.
• Guard Cells controls water loss within the leaf by opening and closing the stomata and allows gas exchange.
• Stomata controls gas exchange in the leaf by closing and opening the pores in the leaves.

  • It assists in eradicating excess water from the leaves, monitoring the movement of water via transpiration
  • It removes oxygen and takes in carbon dioxide at the time of photosynthesis.
• Mitochondria converts chemical energy in food into ATP that cells use to power cell activities.
• The 3 steps of aerobic respiration are:

  1. Glycolysis

  2. Krebs cycle

  3. Electron transport chain
• Glycolysis is the first stage for both aerobic and anaerobic respiration, it's an anaerobic process where glucose is broken down into Pyruvate 

  and ATP (energy), this is because as the bonds of glucose are broken down and rearranged, energy is released. And it occurs in the cytoplasm.
• The Krebs cycle is when Pyruvic acid from glycolysis used to make carbon dioxide, ATP, and electron carrier molecules. This occurs in the mitochondria.
• The Electron Transport Chain uses high-energy electrons from the electron carrier molecules. This step produces water.

  • In Eukaryotes the electron transport chain takes place in the inner mitochondrial membrane
  • In Prokaryotes it takes place in the cell membrane
• Together, glycolysis, the Krebs cycle, and the electron transport chain release about 36 molecules of ATP per molecule of glucose.
• The 36 ATP molecules generated represent about 36 percent of the total energy of glucose. The remaining 64 percent is released as heat.
• Fermentation is the anaerobic process of producing ATP from food in the absence of oxygen
• In anaerobic respiration, Glycolysis is followed by a pathway of fermentation

  • Produces 2 ATP
  • Much less ATP than aerobic respiration
  • Takes place in the cytoplasm of the cell
• In plants and yeasts, the pyruvate from glycolysis is converted into ethanol (alcohol) and carbon dioxide.
• In animals , the pyruvate from glycolysis is converted into lactic acid. 
• Photosynthesis takes place inside the chloroplasts.
• Why are plants green? Plants’ cells have chloroplasts, which contain the pigment chlorophyll. Chlorophyll absorbs most of the colors of the visible light spectrum except green, which is reflected.
• The Sun hits the leaves and the thylakoids sit inside the chloroplast, and they contain the pigment chlorophyll which absorbs the light energy needed for the reaction.
• Alcoholic fermentation takes place in the cytoplasm of the cell.
• The ultimate source of energy for all living things is the sun.
• The process of photosynthesis absorbs light energy and transforms it into chemical energy.
• Chlorophyll is located in the thylakoid membranes of the chloroplast. It is the pigment in the chloroplast that captures sunlight and absorbs light energy.
• Pigments are compounds that absorb a particular wavelength of visible light.
• Light-dependent reactions occur in the thylakoid membranes of chloroplasts and depend upon the presence of light.
• Light-independent reactions take place in the stroma.
• Light-independent reactions do not directly depend on light, but it requires ATP and other products from the light-dependent stage. Requires ATP.
• Often referred to as the Calvin Cycle.
• Main purpose of the Calvin Cycle is to convert carbon dioxide from the atmosphere into glucose.
• During the light-dependent stage, light energy is captured by chlorophyll. The absorbed energy is used to split water molecules into oxygen and hydrogen protons, hydrogen protons create a gradient that drives the creation of ATP. Oxygen is a byproduct. Creates ATP.
• Cellular energy is energy that cells get from the conversion of glucose into ATP.
• Respiration is the process of breathing in oxygen and breathing out carbon dioxide.
• Glucose is a sugar/organic compound/carbohydrate produced by photosynthesis. $C_6 H_{12} O_6$
• Products are the end result of a chemical equation, the substance that is formed as the result of a chemical reaction