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[A]: Rhizobial aggregates have been ob- ...

[A]: Rhizobial aggregates have been ob- served at distinct sites on curled root hairs.
[R]: The infection thread is formed by a pro- cess of invagination of the hair cell walls in the region of curling

A

If both A and R are true and R is the correct explanation of A

B

If both A and R are true but R is not the correct explanation of A

C

If A is true and R is false

D

If both A and R are false

Text Solution

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The correct Answer is:
A
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Choose the correct sequence of step w.r.t nodule formation in legumes. (a) Root nodule formation (b) Infection thread formation (c ) Curling of root hair (d) Division of cortical cells

Sequential stage for nodule formation are I. Rhizobia multiply and colonize the surrounding roots. II. Rhizobia get attached to epidermal and root hair cells. III. Root hair curl and bacteria invade root hair. IV. Initiation of nodule formation in cortex. V. Infection thread is produced carrying bacteria to cortex. VI. Bacteria released from thread into cells and cause their differentiation in specialized nitrogen fixing cells. VII. Nodule formed establishes a direct vascular connection with the host for exchange of nutrient.

Consider the following steps involved in nodule formation in the root of a legume. (i). Bacteria release chemicals and enzymes. (ii). Bacteria stop dividing and form bacteroides. (iii). Roots secrete chemical atractants. (iv). Formation of infection thread. (v). Formation of nodules. (v). Formation of nodulues. (vi). Division of infected cortical cells. (vii) Curlinig of root hair and degradation of their cell wall. (viii). Infection thread grows along with multiplication of bacteria. Arrange the steps in the right sequence and mark the correct option

Study the given figure which shows the development of root nodules in soyabean. Match the correct explanation and find the correct sequence for labelled diagrams. (I) Rhizobium bacteria contacting a susceptible root hair. (II) A mature nodule having vascular connection with roots. (III). Infection thread carrying bacteria to the inner cortex. (IV). Curling of root hair due to successful infection.

Select the correct statements (A) From the region of elongation, some of the epidermal cell for root hairs (B) Pneumatophores are seen in Rhizophora (C) Adventitous roots are seen in the Banyan tree (D) Maize and sugarcane have prop roots

Select the combination of option that will correctly complete the below statements. I. A typical eukaryotic cell has membrane bound distinct structures namely,(P). II. All the prokaryotes are known to have a layer of cell wall around its cell membrane except (Q) III. A special membranous structure found in a bacteria is (R) which is formed by the extensions of the plasma membrane of the cell. IV. (S) are thin filamentous extensions from cell wall that helps the bacterial cell with motility.

Read the following statement with 1-2 blanks in each one of them: (i). In monocot root, a large number of vascular bundles are arranged in the form of a ______around the central _______. Due to the presence of ______,the endodermal substances between cortex and pricycle, in primary dicot root. (iii). The epidermis of stem of sunflower bears several unbranched _____hair. (iv). The central portion of a dicot stem is usually occupied by_____comprising of thin-walled parenchymatous cells. Select the option that correctly fills the blanks in any two of them

TRUEMAN BIOLOGY-Plant Physiology -ASSERTION AND REASON
  1. [A]: The evolution of molecular oxygen is con- cerned with photosystem...

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  2. [A]: Hill and Bendall proposed Z-scheme and suggested that photosystem...

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  3. [A]: Rhizobial aggregates have been ob- served at distinct sites on cu...

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  4. [A]: Light is very important external factor of transpiration. [R]:...

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  5. [A]: Wax, resin and suberin coating on the surface of plant parts redu...

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  6. [A]: Gibberellic acid when added to isolated aleurone layer, induces a...

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  7. Assertion : Auxillary buds, in actively growing herbaceous plants, gen...

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  8. Assertion : If you burn a plant , its nitrogen component is given of...

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  9. [A]: Amino acids are converted into ammonia by a group bacteria called...

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  10. [A]: Due to excessive use of fertilizers, the available water to the p...

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  11. [A]: Vernalization is also called as yarovization. [R]: In short day...

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  12. [A]: Fundamental factor in the vernalization is low temperature. [R...

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  13. [Aj: ABA plays an important role in plants during water stress and dro...

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  14. (A]: Cytokinins help in retention of cholorophyll and delayed senescen...

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  15. [A]: The germination of lettuce seeds is stimulated by red light and i...

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  16. [A]: The far-red form of the phytochromes ab- sorb light at 740 nm. ...

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  17. [A]: Elongation and division of cells are pro- moted by gibberellins. ...

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  18. [A]: Senescence effect can be reversed by cytokinin. [R]: The loss ...

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  19. [A]: Wilting occurs due to loss in turgidity. [R]: Turgor pressure c...

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  20. [A]: Plasmolysis is seen by both living and dead cells. [R]: Both ty...

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