Question
The steps involved in the process of soyabean root nodule formation are :
A. Bacteria emits signals to stimulate root hairs to elongate
B. Cortex and pericycle cells begin division
C. Roots emits signals to attract Rhizobium
D. Bacteria within vesicles develop into bacteroids
Choose the correct answer from the options given below :
The correct answer is
C, A, B, D
Soybean Root Nodule Formation Steps
The formation of root nodules in soybean is a complex symbiotic process involving specific signaling between the plant and Rhizobium bacteria. This process is crucial for nitrogen fixation.
Sequence of Nodule Formation Events
The correct sequence of events in soybean root nodule formation is:
- C. Roots emits signals to attract Rhizobium: Soybean roots release chemical signals, primarily flavonoids, which attract free-living Rhizobium bacteria in the soil.
- A. Bacteria emits signals to stimulate root hairs to elongate: In response to root signals, Rhizobium bacteria produce their own signals (Nod factors). These Nod factors cause the soybean root hairs to curl and deform, initiating infection.
- B. Cortex and pericycle cells begin division: Concurrently with root hair curling and infection thread formation, the plant's cortical and pericycle cells are triggered to divide, forming the nodule primordium, which is the initial structure of the nodule.
- D. Bacteria within vesicles develop into bacteroids: Once inside the plant cells within the developing nodule, the bacteria are released from the infection thread into membrane-bound vesicles. Here, they differentiate into specialized, nitrogen-fixing forms known as bacteroids.
Therefore, the correct order representing the key stages is C, A, B, D.
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Important Questions from Miscellaneous
- Which of the following relationships is/are not true?
(A). Most probable velocity = $\sqrt{\frac{2RT}{M}}$
(B). PV = $\frac{3}{2}kT$
(C). Compressibility factor Z = $\frac{pV}{nRT}$
(D). Average kinetic energy of gas = $\frac{1}{2}kT$
Choose the correct answer from the options given below - Match List-I with List-II
List-I List-II Electronic Configuration First Ionisation energy (kJ mol$^{-1}$) (A). ns$^2$ (I). 2100 (B). ns$^2$np$^1$ (II). 1400 (C). ns$^2$np$^3$ (III). 800 (D). ns$^2$np$^6$ (IV). 900
Choose the correct answer from the options given below: - The shielding constant of a 2p electron (calculated using Slater's rules) is
- Match List-I with List-II
List-I List-II Spectroscopy Property (A). Raman (I). Polarizability (B). FTIR (II). Dipole Moment (C). UV-Visible (III). Absorbance (D). NMR (IV). Spin
Choose the correct answer from the options given below: - The structure of protein comprises of:
(A). Primary structure of protein is associated with amino acids
(B). Secondary structure of protein is associated to peptides
(C). Tertiary structure of protein is associated with polypeptide chains
(D). Quaternary structure of protein is associated with polypeptide chains
Choose the correct answer from the options given below:
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