6 markers

• What is the first step in phloem loading of glucose?

  Glucose is converted to sucrose
• What is the apoplast route in phloem loading?

  It is an active process for sucrose transport
• What role does the proton pump play in phloem loading?

  It creates a H+ concentration gradient
• How do companion cells adapt structurally for phloem loading?

  They have many mitochondria and increased surface area
• What is passive loading via the symplast route?

  It involves the role of plasmodesmata for sucrose entry
• How does the entry of sucrose affect the water potential of phloem?

  It decreases the water potential of phloem
• What happens to water when sucrose enters the phloem?

  Water enters phloem from surrounding cells
• What is mass flow in the context of phloem transport?

  It is bulk transport of sucrose due to pressure differences
• How does hydrostatic pressure affect phloem transport?

  It creates a gradient from source to sink
• Why is high hydrostatic pressure in source phloem important?

  It explains rapid transport over long distances
• What happens to sucrose after it diffuses from phloem?

  It is converted back to glucose
• How is glucose used after being converted from sucrose?

  It is used for respiration
• What maintains the concentration gradient of sucrose?

  Loss of sucrose from phloem to cells
• What happens when sucrose is lost from the phloem?

  It increases the water potential of phloem
• What occurs as a result of increased water potential in phloem?

  Water leaves phloem to surrounding cells
• What is the result of water leaving the phloem?

  It results in lower hydrostatic pressure
• What is genetic variation?

  The variety of alleles in a population
• How does random fertilization contribute to genetic variation?

  It combines alleles from different parents
• What process produces genetically unique gametes in Hydra?

  Meiosis
• What occurs during crossing over in Prophase 1?

  Alleles are swapped between non-sister chromatids
• How does crossing over affect the base sequence of chromosomes?

  It alters the base sequence of chromosomes
• What is independent assortment in meiosis?

  Random segregation of chromosomes during metaphase
• When does independent assortment occur in meiosis?

  During metaphase 1 and metaphase 2
• How can sperm from one Hydra fertilize an egg from another individual?

  Sperm can travel in water to other Hydras
• Why is it significant that two Hydras can have different alleles?

  It increases genetic diversity in offspring
• What is the role of water in the fertilization process of Hydra?

  It allows sperm to travel to unrelated Hydras
• What cycle shares similarities with the nitrogen cycle?

  Carbon cycle
• What are the similarities between the nitrogen cycle and the carbon cycle?

  • Both involve inorganic gases: CO2 and N2
  • Elements are fixed to organic compounds
  • Incorporated into plants (producers) and then animals (consumers)
  • Animals obtain elements by feeding on plants
  • Decomposing microorganisms break down organic macromolecules
  • Release inorganic molecules: CO2 and NH4^+
  • Microorganisms return elements to the atmosphere
• What inorganic gases are involved in the nitrogen and carbon cycles?

  Carbon dioxide and Nitrogen
• How are carbon and nitrogen fixed to organic compounds?

  Through proteins and nucleic acids
• How do animals obtain nitrogen and carbon in the cycles?

  By feeding on plants
• What role do decomposing microorganisms play in the cycles?

  They break down organic macromolecules
• What inorganic molecules are released during decomposition?

  Carbon dioxide and NH4^+
• What happens to carbon dioxide during decomposition?

  It is released into the atmosphere
• What do denitrifying bacteria release into the atmosphere?

  Nitrogen gas (N2)
• How do the nitrogen and carbon cycles contribute to ecosystem balance?

  They recycle essential elements for life
• What cells are involved in the specific immune response?

  B and T lymphocytes
• How can genes influence specific immune responses?

  They code for different immune cells
• What happens to gene segments in immune cells?

  They recombine to create diversity
• What do alleles code for in immune cells?

  Different variable regions