Question

The smallest indepen dently functioning unit of an organism is a(n) ______. a. cell b. molecule c. organ d. tissue

Short answer

Answer: The smallest independently functioning unit of an organism is the cell.

Step-by-step solution

Identify the smallest independently functioning unit of an organism

To solve this exercise, recall the smallest structural unit in living organisms that can function independently. Go through each option and decide which one is the correct answer.

Analyze each option and provide an explanation

a. Cell: Cells are considered the basic structural units of life. They are the smallest units capable of carrying out all the life processes necessary for an organism to survive. This makes the cell the smallest independently functioning unit of an organism. b. Molecule: Molecules are groups of atoms bonded together. Although they are fundamental building blocks of living organisms, they cannot function independently to perform all of the necessary life processes. c. Organ: Organs are groups of tissues that work together to perform a specific function. They are not the smallest unit capable of independent functioning, as they consist of smaller units like tissues and cells. d. Tissue: Tissues are groups of cells working together to perform a specific function. While tissues are essential for an organism's functioning, they are not the smallest unit capable of independent functioning, as they are composed of cells.

Provide the correct answer

Based on the analysis of each option, the correct answer is: a. Cell The cell is the smallest independently functioning unit of an organism, as it can carry out all the life processes necessary for an organism to survive.

Key concepts

Basic Unit of Life

In cell biology, the term **"Basic Unit of Life"** refers to the smallest structural and functional unit that can exist independently and carry out life processes in living organisms. At the core of this concept is the cell, which serves as the building block for all life on Earth. Every living organism, from the simplest single-celled bacteria to complex multicellular beings like humans, is composed of these fundamental units.
Cells are incredibly versatile and can perform a variety of functions required for life. They are capable of growth, reproduction, metabolism, and response to stimuli. Each cell contains the necessary genetic material and machinery to perform these tasks independently.
There are broadly two types of cells: **prokaryotic cells** (found in organisms like bacteria) and **eukaryotic cells** (found in plants, animals, fungi, and protists).

• **Prokaryotic Cells:** Simplest form, lacking a nucleus.
• **Eukaryotic Cells:** More complex, containing a nucleus and specialized structures called organelles.

By understanding cells, we grasp how life operates at its most fundamental level, revealing the intricate and fascinating complexity of living organisms.

Life Processes

Life processes are vital activities carried out by cells to maintain life. Despite the diversity among living organisms, these processes are fundamental and universal, enabling organisms to survive, grow, and reproduce. These processes include respiration, metabolism, reproduction, and adaptation, among others.
Here are a few essential life processes observed in cells:

• **Metabolism:** The sum of all chemical reactions that occur within a cell, involving catabolism (breaking down molecules) and anabolism (building up molecules).
• **Cellular Respiration:** The process by which cells convert nutrients into energy, primarily in the form of ATP (adenosine triphosphate).
• **Reproduction:** Cells replicate through processes such as mitosis (in eukaryotes) and binary fission (in prokaryotes).
• **Transport and excretion:** Movement of materials in and out of the cell and disposal of metabolic wastes.

Each cell must carry out these processes to ensure the organism's overall health and well-being. Comprehending life processes at the cellular level helps elucidate how higher functions in the body arise from these microscopic interactions.

Independent Functioning Unit

An independent functioning unit within an organism is an entity that can perform all necessary life processes autonomously. In the context of cell biology, each cell acts as this autonomous unit. This capability is what defines a cell as the smallest independently functioning entity in an organism.
Cells display several unique features that allow them to operate independently:

• **Self-sufficiency:** Each cell contains its own set of genetic material, allowing it to reproduce and repair itself.
• **Autonomous Functioning:** With structures like mitochondria for energy production and ribosomes for protein synthesis, cells manage essential tasks on their own.
• **Adaptability:** Cells can adjust to external changes, maintaining homeostasis by altering processes as needed.

Despite functioning individually, cells often work together to form tissues, organs, and entire organisms. This cooperation allows for complex functions and more efficient survival strategies. Thus, while cells are self-sufficient, they also demonstrate the unity in diversity—working collaboratively to sustain life.