Problem 121 - Objective Biology for NEET

Question

Which of the following is correct about vacoule? (a) Vacuole contain water sap, excretory product and other material not useful for the cell. (b) In plant cell the vacuole can occupy up to 90 per cent of the volume of the cell. (c) The vacuole is bounded by tonoplast. (d) All of these

Step-by-Step Solution

Answer

The correct answer is (d) All of these. Each individual statement (a), (b), and (c) correctly describes an aspect of the vacuole.

Step 1: Assessing Statement (a)

Vacuole is a cellular organelle that contains water sap, excretory product and other substances not useful for the cell. This is because vacuoles serve as storage and waste disposal sites. Therefore, the first part of statement (a) is correct.

Step 2: Assessing Statement (b)

The size of the vacuole varies from cell to cell. In plant cells, it is true that vacuoles can be very large and can occupy up to 90 per cent of the cell's volume. Therefore, statement (b) is correct.

Step 3: Assessing Statement (c)

The vacuole is indeed bounded by a membrane called tonoplast. This membrane serves to separate the contents of the vacuole from the rest of the cell. Thus, statement (c) is correct.

Step 4: Reviewing all Statements

Considering all the assessments, every statement (a), (b) and (c) is correct. Therefore, statement (d) 'All of these' is the correct answer because it encompasses all the other statements.

Key Concepts

Tonoplast

The tonoplast is a specialized membrane surrounding the vacuole in plant cells. Its primary function is to act as a barrier, keeping the contents of the vacuole separate from the cell's cytoplasm. This separation is crucial because vacuoles often contain materials such as water, enzymes, and waste products that might be harmful if released into the cell.

The tonoplast is selectively permeable, which means it allows certain substances to pass through while keeping others out. This permeability is essential for maintaining the balance of ions and molecules within the vacuole, ultimately helping in the cell's turgor pressure and contributing to the plant's structural integrity.

Furthermore, the tonoplast plays a significant role in osmoregulation by controlling the inflow and outflow of water and solutes. This process helps cells adapt to changes in environmental conditions.

Cellular organelle

A vacuole is a type of cellular organelle predominately found in plant cells. Organelles are specialized structures within a cell that perform distinct functions necessary for the cell's survival and proper functioning.

The vacuole serves several roles within plant cells. It acts as a storage center for nutrients and waste products, ensuring that potentially harmful substances are isolated from the cell's active regions. It also stores water and helps maintain the cell's turgidity, which keeps the plant upright.

Other examples of cellular organelles include the nucleus, mitochondria, and chloroplasts, all of which contribute to the cell's overall function. Each organelle works in concert with others to keep the plant cell healthy and responsive to environmental changes.

Plant cell structure

Plant cells are unique due to several structural components that differentiate them from animal cells. One of the prominent features of plant cells is their large central vacuole, which can occupy a significant portion of the cell's volume—up to 90% in some cases.

This large vacuole is essential for storing compounds that the plant cell needs, such as water, ions, and sometimes even proteins and polysaccharides. The size and pressure of the vacuole contribute significantly to maintaining the cell's structure, providing rigidity to plant cells which is essential for plants to stand upright.

Another unique structure in plant cells is the cell wall, composed mostly of cellulose, which provides additional support and protection. Alongside the vacuole and tonoplast, these structural elements enable plants to manage resource storage and waste removal efficiently.

Water sap in vacuoles

Water sap within vacuoles is a crucial element for plant cell vitality. This sap is primarily composed of water but also contains a mix of minerals, nutrients, and waste products.

The presence of water in the vacuole contributes to the cells' turgor pressure, which is the force exerted by stored water pushing outwards against the cell wall. This pressure is vital for maintaining the structure of the plant, keeping it robust and flexible.

Additionally, the sap can contain secondary metabolites and other compounds beneficial for plant defense and metabolism. By storing these compounds, vacuoles help the plant cope with environmental stresses, such as drought or pathogen attacks.