A. Formation of bacteroids and differentiation into nitrogen fixing symbiosomes
B. Attachment of bacterial cells to root hairs
C. Plant root hair with attached Rhizobium undergoes curling
D. Bacterial penetration into root hair cell and cell to cell spread of rhizobia
E. Plant root releases flavonoids
Choose the correct answer from the options given below :
Root Nodule Formation: Key Steps
The formation of root nodules is a complex symbiotic interaction essential for nitrogen fixation in legumes. The process involves sequential steps starting with chemical signaling and ending with functional nitrogen-fixing units.
Sequence of Events
Here are the steps involved in root nodule formation, arranged in the correct chronological order:
- E. Flavonoid Release: The process begins when the legume root releases specific flavonoids into the soil. These chemicals act as signals to attract and stimulate compatible Rhizobium bacteria.
- B. Bacterial Attachment: Responding to the flavonoid signal, Rhizobium bacteria attach themselves to the surface of the plant root hairs.
- C. Root Hair Curling: Upon attachment, the root hair undergoes significant curling, trapping the bacteria and preparing for entry.
- D. Bacterial Penetration: The bacteria penetrate the root hair cell wall, often through an 'infection thread' – a tube-like structure formed by the plant cell membrane. The bacteria then multiply and spread within the root cortex, moving cell-to-cell.
- A. Symbiosome Formation: Inside the root cells, the bacteria are released from the infection thread and differentiate into specialized nitrogen-fixing forms called bacteroids. These bacteroids reside within plant-derived membrane sacs, forming structures called symbiosomes, which are the sites of nitrogen fixation.
Correct Order Summary
Therefore, the correct order of the steps is:
E → B → C → D → A
This sequence highlights the progression from initial molecular signaling to the establishment of a functional nitrogen-fixing symbiosis within the root nodule.
Similar Questions
- Arrange the following steps of crossing over in correct order :
A. Pachytene stage
B. Synapsis of homologous chromosomes
C. Separation of homologous chromosomes
D. Breakage and reunion of chromatids
E. Formation of chiasmata
Choose the correct answer from the options given below : - Arrange the following steps in lac operon induction in correct order :
A. Formation of mRNA
B. Binding of lactose to repressor
C. RNA polymerase binds to promoter
D. Transcription of structural genes
E. Removal of repressor from operator
Choose the correct answer from the options given below : - Arrange the steps in southern blotting in correct order :
A. Transfer of DNA to nitrocellulose membrane
B. Detection of hybridized probe
C. Restriction digestion of DNA
D. Hybridization with labelled probe
E. Gel electrophoresis
Choose the correct answer from the options given below : - Arrange the steps of endospore formation in correct order :
A. Cortex and spore coat formation
B. Maturation and release of endospore
C. DNA replication and axial filament formation
D. Engulfment of forespore
E. Asymmetric septum formation
Choose the correct answer from the options given below : - Arrange the steps in antigen processing by endocytic pathway in correct order :
A. Recognition by CD4+ T cells
B. Antigen uptake by APC
C. Transport of MHC-peptide complex to cell surface
D. Peptide loading onto MHC class II molecule
E. Fusion of phagosome with lysosome
Choose the correct answer from the options given below : - Arrange the steps of agarose gel electrophoresis in correct order :
A. Preparation of agarose gel
B. Visualization under UV light
C. Loading of DNA samples
D. Migration of DNA fragments
E. Application of electric current
Choose the correct answer from the options given below : - Arrange the steps of life cycle of phage T4 in correct sequence.
A. Lysis of the host cell
B. Injection of phage DNA
C. Synthesis and assembly of phage components
D. Adsorption of the phage
E. Degradation of host DNA
Choose the correct answer from the options given below : - Arrange the following centrifugal speeds in an order to be used when a cell homogenate is to be separated into various fractions.
A. 1000 g
B. 80,000 g
C. 1,50,000 g
D. 20,000 g
E. 60,000 g
Choose the correct answer from the options given below : - Arrange the components of photosynthetic machinery of purple bacteria in a sequence followed for flow of electrons :
A. Quinone
B. P870
C. Cyt bC1 complex
D. Cyt C2
E. Pheophytin
Choose the correct answer from the options given below : - Arrange the steps in cloning and expressing a gene in correct order :
A. Introduction of recombinant molecule into new host that expresses the gene
B. Use of restriction enzymes or PCR to generate fragments of DNA
C. Protein purification
D. Isolation of DNA to be cloned
E. Generation of a recombinant molecule by inserting DNA fragments into vectors
Choose the correct answer from the options given below :
Important Questions from Mixed Topic (CUET PG)
- Who was the founder of Bolshevik Communist party?
- What is the key guide to statecraft in the realist tradition?
- Chronologically arrange the events in the Cold War period.
A. Berlin Wall is constructed
B. Communist China joins the UN
C. Soviet invasion of Czechoslovakia
D. Berlin Blockade
Choose the correct answer from the options given below: Morgenthau's principles of political realism are:
A. Politics is rooted in permanent and unchanging human nature which is basically self centred, self-regarding and self-interested
B. Politics is an autonomous sphere of action and cannot therefore be reduced to morals
C. International Politics is an arena of conflicting self-interests
D. The ethics of international relations is situational ethics which is very different from private morality
Choose the correct answer from the options given below:Who among the following political thinkers consider the anarchical self help system to be a compelling factor for States to maximise their relative power positions?
