Biology Study Guide Quiz PDF

Chapter 8: Section 1 - How do Organisms Obtain Energy? Cellular processes require energy to work. Thermodynamics: Study of the flow and transformation of energy. ○ Law 1: Energy changes form, but it cannot be created or destroyed. ○ Law 2: Energy cannot be conve...

Chapter 8: Section 1 - How do Organisms Obtain Energy? Cellular processes require energy to work. Thermodynamics: Study of the flow and transformation of energy. ○ Law 1: Energy changes form, but it cannot be created or destroyed. ○ Law 2: Energy cannot be converted without the loss of usable energy. That is entropy: Disorder, always increasing. Examples You heat a soup: The energy of the fire is transformed into heat in the soup. Hot coffee: It cools in a cold environment because the heat goes into the air, they exchange roles. - How do Organisms Get Energy From the Sun? All the energy for life comes from the sun. Autotrophs: Directly, light energy to chemical energy. Plants and bacteria. Heterotrophs: Indirectly, is ingested by other organisms to obtain energy Animals and humans. - Metabolism Chemical reactions in a cell→metabolism. Metabolic pathway: Series of chemical reactions, result of one reaction is used in the next. Apple→Glucose→ATP→Energy. ○ Anabolic Pathway: Use energy to build larger molecules. Example: Photosynthesis: Light energy→chemical energy→glucose (larger molecule). ○ Catabolic Pathway: Release energy by breaking large molecules. Example: Cellular respiration (Derive energy from glucose): Glucose (large molecule)→carbon dioxide and water (smaller molecules).  - ATP: Unit of Cellular Energy Cells store chemical energy in biological molecules. Adenosine Triphosphate (ATP): Most important biological molecule and energy-storing (Work: Miosis, mitosis, reproduction). ○ Structure: Adenine base, ribose sugar and 3 phosphates. ○ Function: Release energy when the bond between the 2 and 3 phosphate groups are broken. Transforms into a molecule called ADP (2 phosphates). Chapter 8: Section 2 - Photosynthesis Process in which light energy changes into chemical energy in plants. Nearly all life depends on photosynthesis. Needs sun, water, carbon dioxide and soil→oxygen and glucose. Equation: 6CO2 + 6H2O → Light → C6H12O6 + 6O2 - Phase One: Light Dependent Reactions Light energy is absorbed and changed into chemical energy in the form of ATP and NADPH (Both carry energy). Chloroplast: Plant cell organelle that captures the light (Photosynthesis). Disc shaped. ○ Compartments Thylakoids: Flattened saclike membranes. Grana: Stacks of thylakoids. Stroma: Fluid-filled space outside the grana.  Pigments: Found in thylakoid membranes, light-absorbing colored molecules. ○ Chlorophyll: Major light-absorbing pigments in plants, absorbs violet-blue and reflects green light. ○ Carotenoids: Absorb blue and green light and reflect yellow, orange, and red light. As trees prepare to lose their leaves, chlorophyll molecules break down revealing the colors of other pigments. Electron Transport The thylakoid membrane has a large surface area, providing space for a large number of electron transporting molecules. Photosystems: Pigments that absorb light and proteins, located in the thylakoid membrane. 1. Light energy excites electrons in photosystem II and causes the splitting of a water molecule, releasing an electron that goes to the electron transport system, a hydrogen ion (H+ or proton) in the thylakoid space, and oxygen as a waste product. Activated electrons from photosystem Il→acceptor molecule→transfers electrons→photosystem I. 2. Photosystem I transfers the electrons to a protein called ferredoxin→transfers the electrons to the carrier molecule NADP+, forming NADPH. 3. Electron transport→proton gradient→chemiosmosis→ATP. - Phase Two: Light Independent Reactions Chemical energy is used to synthesize glucose. Takes place in the stroma. 1. Carbon fixation: Ribulose bisphosphate-6→CO molecules→6CO→3-PGA. 2. The energy in ATP and NADPH is used to change 3-PGA into G3P. 3. Some G3P molecules leave the cycle to help make glucose and other organic compounds. 4. Rubisco (enzyme) converts the remaining G3P molecules into 5-carbon molecules called ribulose 1,5-bisphospates (RuBP).  - Alternative Pathways C4 Photosynthesis might be difficult if the plant grows in a hot and dry environment. Tropical plants such as sugarcane and corn use the C4 pathway. Function: Instead of 3 carbon molecules of the Calvin cycle, it uses 4. Less water is lost. CAM Plants like Cacti and orchids are found in deserts. Function: Collect CO at night and store it in organic compounds. During the day, release CO, from organic compounds for the light-dependent cycle of photosynthesis.