Problem 25 - Objective Biology for NEET

Question

In question 23 and 24 respectively growth can be expressed as increase in cell. (a) Size, number (b) Volume, size (c) Number, size (d) Size, volume

Step-by-Step Solution

Answer

The correct answer is (a) Size, number as it accurately represents the two aspects of cellular growth.

Step 1: Understanding the Nature of Growth

Cellular growth can have two aspects. One, the process by which a cell increases in size - which refers to increasing dimensions, and two, the process in which cells multiply, thereby increasing the number of cells.

Step 2: Identifying the Options

Looking at the options, it is clear that cell growth can be expressed as both an increase in size (whether by individual cell growth or overall accumulation effect) and number, due to cell division. Thus, the correct answer is (a) Size, number.

Step 3: Verifying facts

Based on our understanding of cell growth, we can fact check this by referring to a biology book or authentic website to confirm that cell growth indeed involve both increase in size and number of cells. The other options do not quite capture the essence of cellular growth as accurately.

Key Concepts

Cell Division

When we talk about cell division, we're referring to the biological process by which a single cell splits into two or more daughter cells. This is a fundamental part of the life cycle of any organism. Cell division serves several purposes:

• Growth: As an organism grows, the number of cells increases. This is achieved through repeated rounds of cell division.
• Repair and Maintenance: Cell division helps in repairing damaged tissues and replacing old cells.
• Reproduction: For single-celled organisms, cell division is a method of reproduction. For multicellular organisms, it is a means to produce gametes for sexual reproduction.

There are several types of cell division, with the most common being mitosis and meiosis. Mitosis results in two identical daughter cells, usually involving somatic cells, while meiosis leads to four genetically unique cells, typically germ cells.
Understanding cell division is crucial because it explains how organisms develop and maintain their physiological processes.

Cell Size Increase

An increase in cell size is another aspect of cellular growth and involves the enlargement of the cytoplasm and cell membrane. This process occurs because the cell accumulates more cytoplasm, creates more organelles, and sometimes develops larger vacuoles to store nutrients or waste.
Factors influencing cell size increase include:

• Nutrient Availability: Adequate nutrients can lead to a bigger cell volume as the cell builds its components for functionality.
• Gene Expression: Specific genes can regulate the size of the cell by influencing growth factors and protein production.
• Environmental Conditions: Temperature, light, and surrounding medium can impact how a cell grows in size.

Larger cells usually exhibit a greater surface area to volume ratio, which affects the rate of nutrient exchange and metabolic activity. However, there is usually a limit to how large a cell can grow before division becomes necessary to maintain optimal function.

Biological Processes

Biological processes are the essential activities that occur in living organisms to sustain life. They encompass a wide array of chemical reactions and physical activities. Here are some key processes related to the growth and maintenance of cells:

• Metabolism: The chemical processes that convert nutrients into energy and building blocks for the cell. This includes catabolism (breaking down molecules) and anabolism (building up molecules).
• Protein Synthesis: The creation of proteins, which are critical for cell structure and function, carried out via transcription and translation.
• Cellular Respiration: The process by which cells break down glucose and other molecules to release energy (ATP), vital for all cellular activities.
• Cell Cycle Regulation: The series of events that take place in a cell leading to its division and duplication. This involves checks and balances to ensure proper division and prevent errors like mutations.

Each of these processes is interlinked, supporting the cell's ability to grow, replicate, and fulfill its role within the organism. Understanding these biological processes helps us grasp how life persists from the smallest cell to the largest ecosystems.