Home
Class 12
BIOLOGY
Asserion : Long distance flows of photo...

Asserion : Long distance flows of photoassimilates in plants occurs through seive tubes
Reason : Mature seive tubes have parietal cytoplasm and prforated seive plates

A

If the both assertion and reason are true and the reason is the correct explanation of the assertion

B

If both assertion and reason are true and the reason is not the correct explanation of the assertion

C

If assertion is true but reason is false

D

If both assertion and reason are false statements.

Text Solution

Verified by Experts

The correct Answer is:
A
The main function of sieve tube is the transport of blood products from greeen and storage organs of the plant to other organs of the plant. The seive elements are seive tubes arranged one above the other and have sieve plates (obligue or transverse perforated speta) on their end walls. The cytoplasm occur in the form of a thin living layer along the inner side of cellulose wall. The nucleus disappears in mature sieve elements.
Promotional Banner

Similar Questions

Explore conceptually related problems

Assertion : long distance flow of phtoassimilates in plants occurs through sieve tubes. Reason: mature seive tubes have parietal cytoplasm

Assertion : Water and mineral uptake by root hairs from the soil occurs through apoplast until it reaches edodermis. Reason : Mature sieve tubes have parietal cytoplasm and perforated sieve plates.

Identify the statements as true(T) or false(F). A. Xylem fibres are the components of xylem in all categories of vascular plants. B. Advanced angiosperm families like Winteraceae & Trochodendraceae do not have vessals. C. Seive tubes & companion cells are ontogenetically related & are called sister cells. D. The cytoplasm of a mature seive tube occurs in the form of a thin-living layer along the inner side of cell walls.

Assertion (A): Seive tubes are made up of sieve plates that help in conduction. Reason (R): Phloem parenchyma gives mechanical support.

$ Seive tubes in plants are formed of enucleated cells called seive members. ! All the activities of a seive cell are controlled by nucleated parenchyma cells.

(i) In the arrangement shown in the figure, the tank has a large cross section and the pipes have much smaller cross section. The opening at A is unplugged and the water jet hits the ground surface at a horizontal distance x. (a) Find the level of water (h) in the tube B as water flows out of A. (b) Find x. (i) A flat horizontal surface has a small hole at its centre . A circular glass plate of radius R is placed symmetrically above the hole with a small gap h remainng between the plate and the surface A liquid enters the gap symmetrically from all sides and after travelling radially through the gap finally exits from the hole. The volume flow rate of the liquid coming out from the hole is Q (in m^(3)s^(-1) ). (a) If the flow speed just inside the circumference of the circular plate is V_(0) and the speed (V_(x)) of flow inside the gap at distance x(see figure) from the centre of the hole. (b) Write V_(x) in terms of Q, h and x.