Nitrogen Fixation quiz #2 Flashcards
Nitrogen Fixation quiz #2
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How do animals and humans get usable nitrogen into their bodies?
Animals and humans obtain nitrogen by consuming plants or other animals that contain nitrogen in their tissues. How do herbivores obtain the nitrogen they need?
Herbivores obtain nitrogen by eating plants, which have absorbed nitrogen in the form of ammonium or nitrates. What do lichens do to help create soil in primary succession?
Lichens contribute to soil formation by breaking down rocks and accumulating organic material, which helps create a substrate for other plants to grow. Members of which phylum establish a successful symbiotic relationship with the roots of trees?
Members of the phylum Glomeromycota, which include mycorrhizal fungi, establish symbiotic relationships with tree roots. How do plants get nutrients from animals?
Carnivorous plants obtain nutrients, including nitrogen, by capturing and digesting animals. How do animals obtain usable nitrogen, and why is it important?
Animals obtain nitrogen by consuming plants or other animals, and it is important for synthesizing proteins and nucleic acids. What role do rhizobia bacteria play in nitrogen fixation?
Rhizobia bacteria fix atmospheric nitrogen into ammonia within the root nodules of legumes, providing usable nitrogen to the plant. How do mycorrhizal fungi assist plants in nutrient absorption?
Mycorrhizal fungi increase the surface area for absorption and help break down organic matter, providing nutrients like nitrogen and phosphorus to plants. What is the energy requirement for converting one molecule of N2 into ammonia?
Converting one molecule of N2 into ammonia requires 16 ATP and 8 high-energy electrons. Why can't plants directly absorb atmospheric nitrogen?
Plants cannot absorb atmospheric nitrogen because it is in a gaseous form (N2) that they cannot utilize directly. Why is nitrogen essential for living organisms?
Nitrogen is essential because it is a key component of nucleic acids and proteins, which are fundamental to all living cells. Why can't plants directly use atmospheric nitrogen (N2)?
Plants cannot use atmospheric nitrogen because N2 is very stable and inert, making it unavailable for direct absorption and use by plants. Which enzyme complex is responsible for nitrogen fixation in bacteria?
The enzyme complex responsible for nitrogen fixation is called nitrogenase. What is the mutualistic relationship between legumes and rhizobia bacteria?
Legumes provide carbohydrates and protection to rhizobia bacteria, which in turn fix atmospheric nitrogen into a form the plant can use. How do legumes attract rhizobia bacteria to their roots?
Legumes release flavonoids into the soil, which attract rhizobia bacteria. What is leghemoglobin and what is its function in root nodules?
Leghemoglobin is an oxygen-binding molecule in root nodules that protects nitrogenase from oxygen, ensuring efficient nitrogen fixation. What is the difference between ectomycorrhizae and arbuscular mycorrhizae?
Ectomycorrhizae wrap around plant cells without penetrating them, while arbuscular mycorrhizae penetrate into the cortical cells of plant roots. Why is nitrogen fixation considered an energy-intensive process?
Nitrogen fixation is energy-intensive because breaking the triple bond in N2 requires a large input of ATP and high-energy electrons. What role do decomposers play in the nitrogen cycle?
Decomposers break down organic matter, releasing ammonium and other nitrogen compounds into the soil for plant uptake. How do plants support the energy needs of nitrogen-fixing bacteria?
Plants provide carbohydrates to nitrogen-fixing bacteria, which the bacteria use to generate ATP for nitrogen fixation. What are endophytes and how do they relate to nitrogen fixation?
Endophytes are organisms that live inside plant tissues; rhizobia are endophytic bacteria that fix nitrogen within legume root nodules. What is the role of flavonoids in the legume-rhizobia interaction?
Flavonoids are chemical signals released by legume roots to attract rhizobia bacteria. What is the primary source of nitrogen for most plants?
The primary source of nitrogen for most plants is ammonium and nitrate produced by nitrogen-fixing bacteria and decomposers. What is the ecological importance of nitrogen fixation?
Nitrogen fixation makes atmospheric nitrogen available to living organisms, supporting growth and maintaining ecosystem nutrient balance. What is the function of nitrogenase in the nitrogen cycle?
Nitrogenase catalyzes the conversion of atmospheric nitrogen (N2) into ammonia (NH3) during nitrogen fixation.
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