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Nitrogen Fixation quiz #1

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  • What is nitrogen fixation and which organisms primarily perform it in plant roots?

    Nitrogen fixation is the process of converting gaseous nitrogen into a usable form like ammonia, primarily performed by rhizobia bacteria in the roots of legumes.

  • What family of plants commonly hosts rhizobia bacteria for nitrogen fixation?

    The legume family, also known as Fabaceae, commonly hosts Rhizobia bacteria for nitrogen fixation.

  • What are nodules in the context of nitrogen fixation?

    Nodules are swollen nodes or lumps in the roots of legumes where rhizobia Rhizobia infect the plant to perform nitrogen fixation.

  • How do plants attract Rhizobia bacteria to their roots?

    Plants release chemicals called flavonoids into the soil to attract Rhizobia bacteria.

  • What is the role of leghemoglobin in nitrogen fixation?

    Leghemoglobin binds oxygen to protect the nitrogenase enzyme from oxygen poisoning during nitrogen fixation.

  • What is the mutualistic relationship between legumes and Rhizobia bacteria?

    Legumes provide carbohydrates and protection to Rhizobia bacteria, which in turn provide usable nitrogen to the plants.

  • What are mycorrhizae and how do they benefit plants?

    Mycorrhizae are associations between fungal hyphae and plant roots that help plants absorb nutrients like nitrogen and phosphorus.

  • What is the difference between ectomycorrhizae and arbuscular mycorrhizae?

    Ectomycorrhizae wrap around plant cells without penetrating them, while arbuscular mycorrhizae penetrate the cortical cells of plant roots.

  • What is the role of detritivores in the nitrogen cycle?

    Detritivores, such as fungi and bacteria, break down organic matter, releasing nitrogen and other nutrients into the soil.

  • What is the significance of the cortex in nitrogen fixation by Rhizobia?

    The cortex is the inner part of the plant root where Rhizobia bacteria set up and perform nitrogen fixation.

  • What is the function of nod factors in the nitrogen fixation process?

    Nod factors are signals released by Rhizobia bacteria that stimulate root hairs to allow bacterial entry into the plant cortex.

  • How do plants and Rhizobia bacteria support each other energetically during nitrogen fixation?

    Plants provide carbohydrates to Rhizobia bacteria, which convert them into ATP to meet the high energy demands of nitrogen fixation.

  • What is the role of flavonoids in the nitrogen fixation process?

    Flavonoids are chemicals released by plant roots to attract Rhizobia bacteria for nitrogen fixation.

  • What is the primary benefit of nitrogen fixation for plants?

    The primary benefit of nitrogen fixation for plants is the conversion of gaseous nitrogen into a usable form like ammonia, which is essential for plant growth.

  • What is nitrogen fixation?
    Nitrogen fixation is the process by which bacteria and archaea convert atmospheric nitrogen (N2) into ammonia (NH3), making it usable for plants.
  • Why is nitrogen essential for living organisms?
    Nitrogen is essential because it is a required element in nucleic acids and proteins.
  • What percentage of the atmosphere is composed of nitrogen gas (N2)?
    Approximately 78% of the atmosphere is composed of nitrogen gas (N2).
  • Why can't plants absorb atmospheric nitrogen directly?
    Plants cannot absorb atmospheric nitrogen directly because they cannot utilize gaseous N2; they rely on nitrogen fixation to convert it into a usable form.
  • What are the two main forms of nitrogen that plants absorb?
    Plants mainly absorb nitrogen in the forms of ammonium (NH4+) and nitrates (NO3-).
  • What role do decomposers play in the nitrogen cycle?
    Decomposers contribute to the nitrogen cycle by breaking down organic matter, releasing ammonium (NH4+) into the soil.
  • What is the enzyme complex that facilitates nitrogen fixation?
    The enzyme complex that facilitates nitrogen fixation is called nitrogenase.
  • How much energy is required to convert one molecule of N2 into two molecules of NH3?
    Converting one molecule of N2 into two molecules of NH3 requires 8 high-energy electrons and 16 ATP.
  • What is the mutualistic relationship between legumes and rhizobia bacteria?
    Legumes provide carbohydrates and protection to rhizobia bacteria, which in turn fix nitrogen for the plants.
  • What is leghemoglobin and its function in nitrogen fixation?
    Leghemoglobin is a molecule produced by legumes that binds oxygen to protect the nitrogenase enzyme from oxygen poisoning.
  • What are mycorrhizae and their role in plant nutrition?
    Mycorrhizae are associations between fungal hyphae and plant roots that help plants absorb nutrients like nitrogen and phosphorus.
  • What is the difference between ectomycorrhizae and arbuscular mycorrhizae?
    Ectomycorrhizae wrap around plant cells without penetrating them, while arbuscular mycorrhizae penetrate the cortical cells of plant roots.
  • How do carnivorous plants supplement their nitrogen intake?
    Carnivorous plants supplement their nitrogen intake by consuming animals, which provide nitrogen-rich nutrients.
  • What are flavonoids and their role in the symbiotic relationship between legumes and rhizobia?
    Flavonoids are chemicals released by legume roots that signal rhizobia bacteria to initiate nitrogen fixation.
  • What is the significance of the nitrogen cycle in ecosystems?
    The nitrogen cycle is crucial for converting nitrogen into various chemical forms that can be used by living organisms, maintaining ecosystem health.
  • _____ removes nitrogen from the atmosphere.
    Nitrogen fixation by bacteria and archaea removes nitrogen from the atmosphere by converting gaseous nitrogen (N2) into ammonia (NH3), which plants can then use.