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#propagation

4 public questions tagged with this topic.

Transverse and Longitudinal Waves

Which type of wave cannot propagate through a vacuum?

**Wave classification** depends on particle vibration relative to propagation. Longitudinal waves have particle oscillation parallel to propagation, creating compressions and rarefactions as in sound in air; transverse have perpendicular oscillation. Tuning fork generates longitudinal sound because air cannot sustain shear. Mechanical waves, such as sound (longitudinal) waves, require a medium for propagation because they rely on particle vibrations. Electromagnetic waves, like light, can travel through a vacuum. Using v = fλ and standing-wave condition fₙ = n v/(2L) or v/(4L) as applicable, calculation yields Sound wave, illustrating frequency-length-speed interdependence and quantization by boundaries.

Ref: NCERT > Physics Book > Waves > Transverse and Longitudinal Waves

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BOTANY

How does the presence of stolons help rtain plants in vegetative propagation?

Stolons, such as those found in strawberries, grow horizontally and give rise to new plants at nodes, facilitating vegetative propagation. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept.

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Plant tissue culture 3

Friable callus is mainly used to initiate:

Texture of callus determines suitability for liquid systems. Compact nodular callus consists of tightly packed cells cemented by calcium pectate, resistant to dispersal. Friable type arises when pectin methylesterase activity reduces middle lamella cohesion, producing crumbly masses of loosely associated, highly vacuolated cells with large intercellular air spaces. Upon transfer to agitated liquid Murashige-Skoog medium containing 2,4-D, these fragments break easily into single cells and small aggregates under 100 micrometer diameter, forming homogeneous suspension. Such suspensions exhibit exponential growth, uniform nutrient uptake, and amenability to sieving and plating for single-cell cloning. They serve as source for protoplast isolation and bioreactor inoculum. Compact embryogenic callus retains cohesion and yields poor suspensions. Hence friable callus is specifically maintained and multiplied to initiate cell suspension cultures essential for secondary metabolite production and large-scale propagation. Size distribution analysis via hemocytometer shows friable callus yields high proportion of viable small clusters. Sieving through 250 micrometer mesh enriches for embryogenic units initiating suspensions. Maintenance requires regular subculture of friable clumps to prevent compacting. This physical property exploited in scale-up for bioreactor inoculum and somatic embryogenesis induction protocols.

Ref: Murashige & Skoog 1962 friable callus; Street Plant Tissue 1977 suspension initiation; Dodds & Roberts Experiments 4th ed; NCBI NBK26844 cell suspensions texture importance.

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