The symbiotic nitrogen-fixing bacterium found in root nodules of legumes is:
A. Clostridium
B. Nitrosomonas
C. Rhizobium
D. Azotobacter
Answer: Option C
Solution (By JKExamLibrary)
Rhizobium species infect legume roots, leading to root nodule formation, where they fix atmospheric N₂ into ammonia using nitrogenase enzyme. They are symbiotic, receiving carbohydrates from the plant. Azotobacter and Clostridium are free-living nitrogen fixers. Nitrosomonas is a nitrifying bacterium. Legume-Rhizobium symbiosis is crucial in sustainable agriculture, reducing the need for nitrogen fertilizers.
Explanation:
Parasitism (+/-) is a symbiotic interaction where the parasite benefits at the expense of the host. Examples: tapeworms, Plasmodium. Mutualism is +/+, commensalism +/0, amensalism -/0. Parasites may live on (ectoparasites) or inside (endoparasites) the host.
Explanation:
Chlorophyll a and b absorb red and blue light and reflect green, giving leaves their color. Carotenoids are yellow/orange, anthocyanins red/purple.
Consider statements about microorganisms: 1. Bacteria reproduce asexually by binary fission. 2. Fungi reproduce by spore formation. 3. Viruses can reproduce independently. Which are correct?
Explanation:
Bacteria are prokaryotes that primarily reproduce asexually through binary fission, a process where a single cell divides into two identical daughter cells. Fungi reproduce both sexually and asexually, but asexual reproduction commonly occurs through the formation and dispersal of spores (like conidia or sporangiospores). Viruses are obligate intracellular parasites; they lack the metabolic machinery for independent reproduction and must hijack a host cell's machinery to replicate. Thus, statements 1 and 2 are correct.
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