Problem 10 - Objective Biology for NEET

Question

Select the incorrect matching for component percentage in living cell: (a) Water \(=70\) to \(90 \%\) (b) Proteins \(=10\) to \(15 \%\) (c) Carbohydrate \(-2 \%\) (d) Nucleic Acid \(-5\) to \(7 \%\)

Step-by-Step Solution

Answer

The incorrect matching for component percentage in living cell is (c) Carbohydrate = \(-2 %\).

Step 1: Analyze the given percentages

Look at each of the given component percentages and compare it with the accepted values for the composition of a living cell. These accepted values are generally known facts in high school biology.

Step 2: Compare with the Accepted Values

(a) Water does make up around \(70\) to \(90 %\) of a living cell.\n(b) Proteins also match the known cell composition as they usually account for around \(10\) to \(15 %\) of the cell.\n(d) Nucleic Acid is also correctly represented, with most cell containing around \(5\) to \(7 %\).

Step 3: Identify the Incorrect Matching

From the analysis in step 2, only (c) Carbohydrate - \(2 %\) does not align with the known cell composition. Usually, carbohydrates make up around \(2\) to \(3 %\) of the cell’s makeup, not negative \(2 %\).

Key Concepts

Biological Macromolecules

Biological macromolecules are large, complex molecules that are fundamental to life. They are crucial for cell structure and function. These macromolecules include proteins, carbohydrates, nucleic acids, and lipids. Each one plays a unique role. Proteins, for example, are involved in catalyzing biochemical reactions and providing structural support. Carbohydrates are vital for energy storage and supply. Nucleic acids store and transmit genetic information. Lipids, though not prominently featured in the exercise, are essential for cell membrane structure. Overall, understanding these macromolecules helps us comprehend how cells operate and survive.

Cell Water Content

Water is an abundant and essential component of cells, making up approximately 70% to 90% of a cell’s weight. It plays a vital role in countless cellular processes. As a solvent, water facilitates the movement of ions and molecules throughout the cell. It is also crucial for maintaining the cell's shape and internal environment. Additionally, water is involved in regulating temperature and providing a medium for chemical reactions. Its unique properties, such as cohesion and adhesion, make it indispensable for life on Earth.

Protein Composition in Cells

Proteins are one of the most versatile biological macromolecules present in cells. They account for about 10% to 15% of a cell’s makeup. Proteins are made up of amino acids linked by peptide bonds, forming polypeptide chains. These chains fold into specific shapes that determine the protein’s function. Proteins act as enzymes that increase the rate of biochemical reactions, provide structural support, and assist in cellular communication and transport. They are essential for nearly all cellular activities and processes.

Carbohydrate Content in Cells

Carbohydrates are crucial for storing and providing energy in cells, usually making up around 2% to 3% of the cell composition. They can exist as simple sugars, like glucose, or complex polymers, like starch and glycogen. In addition to energy storage, carbohydrates play a role in cell signaling. They are also involved in certain structural components like cell walls in plants. Despite the importance of carbohydrates, their proportion within cells is relatively small compared to other macromolecules.

Nucleic Acids in Cells

Nucleic acids, such as DNA and RNA, are responsible for the storage and transmission of genetic information. Comprising about 5% to 7% of a cell’s mass, they serve as blueprints for synthesizing proteins and play essential roles in gene expression and regulation. DNA is typically found in the cell nucleus where it stores hereditary information. RNA acts as a messenger, conveying genetic instructions for protein synthesis from DNA to the ribosome. Understanding nucleic acids is key to grasping genetic inheritance and protein production.