Cell Wall Most Important Questions and Answers

General Knowledge on Cell Membrane | Cell Biology

CONCEPTS & THEORIES of Cell Wall

QUESTIONS

Cell Wall Most Important Questions and Answers

Why do plants have a cell wall?

Answer:

The main reason plant cells have cell walls is because unlike animals, they cannot move from place-to-place and have to withstand all types of weather. It provides the basic shape ,structure and support to plants. Cell wall acts as a gatekeeper; it allows certain substances and restricts others.

Here is a list of the basic plant cell wall functions:
(i)Provide support and limited plasticity
(ii)Prevent loss of water
(iii)Protection from insects and pathogens

More about Cell wall function

There are mainly 3 parts of cell wall – Middle lamella, primary cell wall, and in some plants, a secondary cell wall.
(i)The middle lamella in cell wall is responsible for cementing neighbouring cells together.
(ii)The primary cell wall, generally a thin, flexible and extensible layer formed while the cell is growing.
(iii)In some cells, such as the xylem cells, a secondary cell wall is present to which contains lignin. It helps strengthen the cell and makes it waterproof.

More about Cell wall structure

What is a cell wall?

Answer:

The term “cell wall” is confined to the cells of organisms where the plasma membrane/cell membrane is surrounded by another stiff covering called the cell wall. It is a dead covering and permeable to water and all dissolved substances.Cell walls in plants get secondary thickenings (also of hemicellulose, lignin) and provide incredible strength – this makes 50 meter (and taller) trees stand upright. More about Cell wall

Is the cell wall permeable or semi-permeable?

Answer:

The cell membrane is the lipid-protein based biological membrane that separates the interior of ALL cells from their environment. A cell wall provides structure for plant and bacterial cells, is most definitely semi-permeable in plants, allowing small molecules and proteins to pass through based on size, anything under about 30 Kilodaltons. Then the membrane manages the actual transfer of materials to the interior of the cell. However, the cell wall provides low-level nutrients like water and carbon dioxide to flow directly into the cell, and excretion of low-level substances like oxygen to leave the cell. For a plant cell there is a cell membrane INSIDE the cell wall.

Higher level organisms like animals do not have a cell wall, just a cell membrane. For these cells, the cell membrane also manages the movement of water, CO2 and oxygen in and out of the cell, and for all plant and animal cells the membrane is usually “selectively” permeable to specific preferred ions and organic molecules, and has lipid-protein complexes embedded in it to assist in the transfer of other molecules into the cell that the membrane is not initially permeable to. In this sense, a cell membrane is semi-permeable as well.

What is the function of the cell wall in plant cells?

Answer:

The cell wall is a rigid, semi-permeable layer found in plant cells. It serves multiple functions:

Support: the cell wall provides strength and support to the cell and also controls the direction of growth. It also withstands the internal pressure of the cell, preventing the cell from rupturing.

Barrier: the cell wall is semi-permeable, which means that it allows certain substances to diffuse through while keeping other substances out. This helps regulate the concentrations of different substances inside the cell and also helps protect the cell from viruses. More about Cell wall function

How is the cell wall of bacteria different from a plant cell wall?

Answer:

The difference between plant cell walls and bacterial cell walls are
(i)Plant cell walls are made up of cellulose which is basically Beta glucose. On the other hand, bacterial cell walls are made up of peptidoglycan.
(ii)In plant cells, there are used for structural support, maintaining the shape of the cell, and sometimes also in communication with other cells through plasmodesmata, which are channels that connect cell walls of different plant cells and allow communication between them. On the other hand, bacterial cell walls is often used to anchor flagella, maintain the shape, and prevent lysis. More about Bacterial Cell wall

Why don’t animal cells have a cell wall?

Answer:

Animals do not have cell walls because “taxonomists have expelled some organism with cell walls from the Animalia”.Cell walls serve two main purposes: protection and the maintenance of turgor. While some single-celled bacteria and protists do have cell walls for protection, plants and fungi are the only multicellular organisms with cell walls. Animal cells could use the protection offered by cell walls, but they would not require the ability to maintain hypoosmotic conditions. They do not need the extra water for growth or photosynthesis. Cell walls would also limit muscle movements and general mobility.

What organisms other than plants possess a cell wall?

Answer:

Bacteria, archea and fungi possess cell wall but their chemical contistituents are different from plant cell wall. More about cell wall possessing organisms

What is the difference between cell wall and cell membrane?

Answer:


1.Cell membrane is present in all types of cells. i.e human, animal, plant, bacterial etc.Cell wall is Present in only plant cells and bacterial cells.
2.Cell membrane is an organelle of the cell. And is outermost cover in animals and humans. It provides shape to cell which is flexible. Cell wall is the outer non-living cover of the cell but not an organelle. It encloses cell membrane. It also provides a fixed shape. More about Cell Wall Vs Cell Membrane

Is cell wall living or dead and why?

Answer:

Cell wall was considered dead due to presence of cellulose. But with increasing pace in cell biology we got to know that cell wall has certain proteins known as expansins. These proteins were found to have an effect in increasing or decreasing size of cell wall. This change is brought out by external or internal stimulus.This property i.e ability to sense change in environment and then acting correspondingly is one of fundamental properties of life. Hence cell wall is living.

How does the primary cell differ from secondary cell wall?

Answer:


1.primary wall is made up of cellulose,hemicellulose,pectin,protein. But,the Secondary cell wall is made up of cellulose,pectin and some amount of lignin that gives it durability.
2.primary wall is at outside of all walls. But, the Secondary wall originated inside the primary wall.
3.primary wall has the ability to grow or we can say it is flexible. But, the Secondary wall is durable and hard to flexible (due to deposition of lignnin)
4.primary wall is apperas at first. But, the Secondary wall appears lately. More about Cell wall structure

More about Cell Wall

  1. What is Cell wall?
  2. Cell wall is made up of
  3. Cell wall of Fungi
  4. Cell wall of Bacteria
  5. Cell wall structure
  6. Cell wall function
  7. Cell wall is present in
  8. Cell Wall Vs Cell Membrane
  9. Cell wall Vs plasma membrane
  10. Cell wall absent in
  11. Bacterial Cell wall Biosynthesis
  12. Inhibitors of Bacterial Cell Wall Synthesis
  13. Bacillus subtilis of Cell wall
  14. Cell wall composition of Archaebacteria
  15. Gram Positive Cell wall
  16. Cell Wall Multiple Choice Questions(MCQs) and Answers

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