Pits, Biology

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.)

1318_pits.png

(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.

1106_pits 1.png

Posted Date: 10/5/2012 6:03:42 AM | Location : United States







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

Write discussion on Pits
Your posts are moderated
Related Questions
Q. What are respiratory pigments? What is the respiratory pigment present in some arthropods? Which is the analogous molecule in humans? Respiratory pigments are molecules able

Fungi The study of fungi (s. fungus) is called mycology. Fungi are unicellular or multicellular chemoheterotrophic eukaryotes. They may be grouped into yeasts, molds and funga

Q. Guidelines for the Family Members for Healthy Coping? - Patient and the family members should discuss the situation, change in role,time distribution, share of money and oth

Plants - Slow Moving Waters Plant life is abundant in this habitat and includes rooted vascular plants such as pond weeds and grasses, firmly attached aquatic mosses and multi

Q. How is HIV transmitted? What is the disease caused by this virus? The HIV (human immunodeficiency virus) is supposed to be transmitted through blood, semen, vaginal secretio

Osmotic adjustment or Osmoregulation - Osmotic Stress If concentration of soluble matter (in the form of minerals and small organic molecules) builds up in the external medium

Why does the ingestion of vegetable fibers improve the bowel habit in people that suffer from hard stools? Some types of plant fibers are not absorbed by the intestine but play

The period of life cycle of cell (cell cycle) between two consecutive divisions is termed as the Interphase or misleading called resting phase. It is a period

HETEROTROPHI C NUTRITION Animals derive organic food materials by consuming products of plants - Heterotrophic nutrition. T ype s of Heterotrophic Nutrition (i ) H

Follow a cell through the cell cycle. How many copies of each gene are present at each stage?