PITS

• Depressions in secondary cell wall is called pit.
• A pit present on the free cell wall surface without its partner is called Blind pit.
• It consists of 2 parts - Pit chamber and Pit membrane.
• Pit chamber / pit cavity is depression in wall where secondary wall is absent.
• Opening of pit chamber into cell is called pit pore / aperture.
• Pit membrane is formed of (PCW + middle lamella + PCW) it is "trilaminar".
• Pit membrane also called closing membrane.
• Pit membrane is permeable due to permeability of primary cell wall.
• Pits are of 2 types (depending upon the shape of the pit chamber.)

(i) Simple pit

• Pit chamber has uniform width.
• Diameter of lumen remains the same.
• Found in vessels, tracheids & sclerenchyma.

(ii) Bordered pit

• Pit chamber is flask-shaped.
• Diameter of lumen is increases from inner to outer side.
• A disc-shaped thickening called Torus is present in the middle of pit chamber on pit membrane.
• It controls diffusion, it prevents rupturing of pit membrane when unequal pressure is present on its both sides.

Posted Date: 10/5/2012 6:03:23 AM | Location : United States

Ask an Expert

Related Discussions:- Pits, Assignment Help, Ask Question on Pits, Get Answer, Expert's Help, Pits Discussions

Write discussion on Pits
Your posts are moderated

Write your message here..

Related Questions

Keyword and parameter description - goto statement, Keyword and Parameter D... Keyword and Parameter Description: label_name: This is an undeclared identifier which labels an executable statement or the PL/SQL block. You can use a GOTO statement to

Appgen to sap data export, We are seeking a freelance consultant that is fa... We are seeking a freelance consultant that is familiar with Appgen applications. We require exporting all our data into a format appropriate for importing into SAP Business One. Pl

Restriction and and - sql, Restriction and AND - SQL Restriction is av... Restriction and AND - SQL Restriction is available via the WHERE operator, and so it is in SQL. However, by Example showing how a certain simple restriction can be expressed u

Execute privilege, EXECUTE Privilege To call an invoker-rights routine ... EXECUTE Privilege To call an invoker-rights routine straightforwardly, the users should have the EXECUTE privilege on that routine. By yielding the privilege, you permit a user

Triggers, At times, customers make mistakes in submitting their orders and ... At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a trigger that automatically updates the stock level of all pr

Product-specific packages in pl/sql, Product-specific Packages The Ora... Product-specific Packages The Oracle and different Oracle tools are supplied with the product-specific packages which help you to build the PL/SQL-based applications. For illu

Example of coalesce operator - sql, Example of COALESCE operator Examp... Example of COALESCE operator Example: Give the total of marks for each exam (simplified solution) SELECT CourseId, COALESCE ((SELECT SUM (Mark) FROM EXAM_MARK AS EM

Package body in pl/sql, Package Body: The package specification is imp... Package Body: The package specification is implemented by the package body. That is, the package body has the definition of every cursor and the subprogram declared in the pac

Order of evaluation-pl/sql expressions , Order of Evaluation When you do... Order of Evaluation When you do not use the parentheses to specify the order of evaluation, the operator precedence determine the order. Now compare the expressions below: NOT

Write a program, to write a heap sort program usin pl-sql to write a heap sort program usin pl-sql