Test: Cell Wall, Cell Membrane & Glycocalyx - Grade 12 MCQ

Correct option is D.
Bacterial cell walls are made of peptidoglycan also called as murein, which is made from polysaccharide chains cross-linked by unusual peptides containing D-amino acids.

• All bacteria have a cell wall covering the cell membrane, except in the genus mycoplasma.
• Since all bacteria are prokaryotic organisms, they do not have a well – defined nucleus.
• The genetic material is naked.

• Calcium (Ca): Calcium is the main element that occurs in the middle lamella of plant cells.

• Importance of Calcium: Calcium plays a crucial role in the formation of middle lamella in plant cells.


• Function in Middle Lamella: Calcium acts as a cementing agent between adjacent plant cells, helping to hold them together.


• Structural Integrity: The presence of calcium in the middle lamella provides structural integrity to the cell wall and contributes to the overall strength of the plant cell.


• Cell Adhesion: Calcium ions are involved in cell adhesion, ensuring that plant cells stick together and form a cohesive tissue.


• Role in Plant Growth: Adequate levels of calcium are essential for proper plant growth and development, as it influences cell wall formation and stability.

Plasma membrane or cell membrane is the outer covering of all cells but it is present below the cell wall in animal cells. It is mainly composed of phospholipid bilayer structure with embedded proteins and some carbohydrates. Thus, the correct answer is option D.

The plasma membrane or cell membrane is the outer covering of all cells but in a plant cell, it is present below the cell wall. It is mainly composed of phospholipid bilayer structure with the embedded proteins. The membrane proteins are extrinsic (on the surface of the membrane) and intrinsic (across the membrane i.e., cross the bilipid layer). About 70% of the proteins of the plasma membrane are intrinsic proteins. The intrinsic proteins, as their name implies, are firmly embedded in the phospholipid bilayer. Almost all intrinsic proteins contain special amino acid sequences.

• Bacterial have a tightly bound three – layered cell envelope.
• The uppermost layer is the glycocalyx, followed by the cell wall in the middle and the innermost plasma membrane.
• The cell envelope provides protection.

In plant cells, Golgi apparatus consists of a number of isolated units called as dictyosomes while in animal cells it occurs as single compact or loose complex. The dictyosomes are engaged in secretory activities (because secretory materials are produced in dictyosomes) and rapid divisions (because wall materials are synthesized in dictyosomes). 

Cellulose is the most abundant macromolecule on Earth.

• Cellulose fibers are long, linear polymers of hundreds of glucose molecules.
• These fibres aggregate into bundles of about 40, which are called microfibrils.

• Phospholipid: The main component of the plasma membrane is a double layer of phospholipid molecules. These molecules have a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails.


• Extrinsic Protein: These are proteins that are loosely bound to the surface of the membrane. They can act as receptors or enzymes.


• Intrinsic Protein: These are proteins that are embedded within the phospholipid bilayer. They can act as channels, carriers, or pumps for transporting molecules across the membrane.

• The phospholipid bilayer provides a barrier that separates the inside of the cell from the external environment.


• The extrinsic and intrinsic proteins play crucial roles in cell signaling, transport of molecules, and maintaining the structural integrity of the membrane.

• The term "fluid" refers to the ability of phospholipid molecules to move laterally within the membrane, giving it a fluid-like quality.


• The term "mosaic" refers to the diverse composition of the membrane, with proteins scattered throughout like tiles in a mosaic.

• According to the fluid mosaic model proposed by Singer and Nicolson, the plasma membrane is a dynamic structure composed of phospholipid molecules, extrinsic proteins, and intrinsic proteins.


• This composition allows the membrane to carry out essential functions such as selective permeability, cell signaling, and cell-cell recognition.

The correct answer is Cellulose.

• The epidermis is the protective outer layer of clonally related cells covering all plant organs.
• It is made up of cellulose, hemicelluloses, and pectin.

Carbohydrates which are present in the cell membrane take part in cell recognition. Cell recognition is defined as an active process giving rise to a specific response.
Cell adhesion is a good example of cell recognition when it can be demonstrated that the adhesion is mediated by molecules having specific binding properties. Such cell adhesion molecules have now been identified in several cellular systems. Carbohydrates, or sugars, are sometimes found attached to proteins or lipids on the outside of a cell membrane. That is, they are only found on the extracellular side of a cell membrane. Together these carbohydrates form the glycocalyx. The glycocalyx of a cell has many functions. It can provide cushioning and protection for the plasma membrane, and it is also important in cell recognition. Based on the structure and types of carbohydrates in the glycocalyx, your body can recognize cells and determine if they should be there or not.

The plasma membrane or cell membrane is the outer covering of all cells but in a plant cell, it is present below the cell wall. It is mainly composed of phospholipid bilayer structure with the embedded proteins. The fluid nature of membranes is due to the lipids. The lipids can be saturated or unsaturated. More the unsaturation in lipids more the fluidity of the membrane.

• Phospholipids: Phospholipids are the most abundant lipids found in cell membranes. They have a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails, which form a bilayer structure in the cell membrane.


• Cutin, Cholesterol, and Steroids: While cutin is a lipid present in the cuticle of plants, cholesterol is a type of steroid that is found in animal cell membranes. Steroids are a class of lipids that have a different structure compared to phospholipids.


• Role of Phospholipids: Phospholipids play a crucial role in maintaining the structure and function of cell membranes. They help regulate the passage of molecules in and out of the cell, provide a barrier to the external environment, and participate in cell signaling processes.


• Importance in Biology: Understanding the composition of cell membranes, particularly the abundance of phospholipids, is essential in biology as it influences various cellular processes and interactions with the environment.

A plant cell is characterized by a well developed cellulosic cell wall which is dead at maturity and consists lignin. Since cell wall is dead at maturity it does not take part in any physiological or biochemical process and may not allow passing molecule across it. Therefore, the correct answer is option C.

Middle lamella is the cementing material between two cells. It is mostly amorphous, thin and made up of calcium and magnesium pectate. The pectin present in this layer is a heteropolysaccharide which helps to bind the two cells together. It also helps in cell growth and cell wall extension. Thus, the correct answer is option D.

Plasma membrane, also called the cell membrane is mainly composed of lipids and proteins.

• The major lipids are arranged in a bilayer and called as phospholipids.
• Plasma membrane also contains cholesterol.
• Cell membranes also possess protein and carbohydrate as per Biochemical investigation.
• The ratio of lipid and protein varies in different cell types.

For example, in human beings, the membrane of the erythrocyte has approx 40 per cent lipids and 52 per cent protein.

• Glycocalyx: The sticky feature of a bacterial cell is due to the presence of glycocalyx. Glycocalyx is a sticky layer of polysaccharides and proteins that surround the cell wall of bacteria. It helps the bacteria to adhere to surfaces and form biofilms, which can protect them from external threats like antibiotics and immune system attacks.

The middle lamella is a cementing layer of the plant cell wall that holds together adjacent plant cells. It is usually made of calcium and magnesium pectates.

Plant cell is characterised by a well developed cellulosic cell wall which is dead at maturity. Three major algal groups (Chlorophyceae, Rhodophyceae and Phaeophyceae) are included in plant kingdom. Hence, algae have well developed cell wall. A bacteria or prokaryotic cell also has a well developed cell wall but it is not made up of cellulose. Bacterial cell wall is made up of peptidoglycans.
So, the correct answer is 'All of the above'.

• Definition: The plasma membrane is selectively permeable, meaning it allows only certain substances to pass through while blocking others.


• Structure: The plasma membrane is made up of a phospholipid bilayer with embedded proteins that control the movement of substances in and out of the cell.


• Function: Selective permeability allows the cell to maintain homeostasis by regulating the passage of ions, nutrients, and waste products.


• Transport Mechanisms: The plasma membrane uses various transport mechanisms such as passive diffusion, facilitated diffusion, active transport, and vesicular transport to control the movement of molecules.


• Importance: Selective permeability is crucial for the survival of cells as it ensures that essential molecules enter the cell while harmful substances are kept out.

Plasma membrane or cell membrane is the outer covering of all the cells and made up of phospholipid bilayer structure with embedded proteins. The thickness of the plasma membrane ranges from 7.0nm to 10nm or 75A˚ to 100A˚. Thus, the correct answer is option B.

The bacterial cell membrane is made up of proteins and phospholipids. The proteins are randomly distributed in the phospholipid bilayer of the cell membrane.

Pits are discontinuities in the secondary cell wall. there are two main types of pits – simple and bordered. All pits have two essential components – the pit cavity and the pit membrane. In the simple pit, the cavity is nearly constant in width. In the bordered pit, the cavity narrows towards the cell lumen; typically, the membrane is arched over by the secondary cell wall. The pit membrane cosists of primary wall and middle lamella. As a rule, pits in the walls of adjoining cells appear in pairs called pit-pairs, and the common membrane is therefore composed of two primary walls and middle lamella.