Question

Structures composed of two or more tissue types arranged in various proportions and patterns are a. cells. b. tissues. c. organs. d. organ systems. e. organisms.

Short answer

The correct answer is c. organs.

Step-by-step solution

Understanding the Question

The first step is to understand the question. It asks about structures composed of two or more tissue types arranged in various proportions and patterns. In other words, we need to find which of the given options is made up of multiple types of tissues. Now, if we look at the options, we see that they all represent different levels of the biological organization hierarchy.

Analyzing the Options

In the second step, we go through each option and evaluate whether it meets the conditions set in the question. \n\na. Cells: These are the most basic units of life and do not consist of tissues, so this option is incorrect. \n\nb. Tissues: Tissues are groups of similar cells that perform a common function. However, tissues are not composed of multiple types of tissues, therefore, this option is not correct. \n\nc. Organs: Organs are composed of two or more different types of tissues working together to perform a complex function. This seems to meet the conditions of the question.\n\nd. Organ Systems: These are groups of organs working together to perform a specific bodily function. Although organ systems are composed of organs that contain multiple types of tissues, the organ system itself does not meet the condition because it is composed of organs, not tissues.\n\ne. Organisms: These are individual living entities composed of organ systems, organs, tissues, and cells. Similar to organ systems, organisms don't directly meet the condition set in the question because they're composed of multiple levels of organization, including cells, tissues, organs, and organ systems.

Final Answer

After examining all the options, we find that 'organs' is the level of biological organization that best fits the description given in the question.

Key concepts

Organs

In biology, an organ is defined as a part of an organism that is typically self-contained and has a specific vital function. The heart, liver, brain, and leaf of a plant are all examples of organs.

To truly appreciate an organ, picture it as a collection of various tissue types that are structured in such a way that they work together harmoniously to carry out one or more specific functions. This collaboration is fundamental to the survival of an organism. For example, the human heart consists of muscle tissue for pumping blood, connective tissue to give it structure and support, and nervous tissue to regulate heartbeat.

Importance of Diverse Tissues in an Organ

Just like a symphony orchestra, where various instruments play together to create a harmonious sound, different types of tissues come together to ensure an organ can perform its role effectively. The integration and management of these tissues are critical for the function and efficiency of an organ.

Tissue Types

Tissues are collections of cells that are similar in structure and join together to perform a specific function. There are four main types of tissue in the human body, and understanding each is essential to grasp how our bodies are constructed and function.

These four tissue types are:

• Epithelial tissue: This tissue acts as a covering or lining of body parts, protecting the body and facilitating absorption and excretion.
• Connective tissue: It supports and binds other tissues. Examples include bone, blood, and fat tissues.
• Muscle tissue: This is responsible for movement. It can be voluntary (skeletal muscles) or involuntary (heart and digestive muscles).
• Nervous tissue: It transmits signals throughout the body to coordinate actions.

Each type of tissue has its unique characteristics and functions, and multiple tissue types can be found within organs.

Organ Systems

Organ systems are hierarchically higher than organs in the biological organization structure. They consist of multiple organs working together to execute a broader and more complex set of functions within an organism.

Here are a few examples of organ systems:

• The circulatory system, including the heart, blood vessels, and blood, circulates essential substances like oxygen and nutrients.
• The digestive system, incorporating the mouth, stomach, intestines, and associated organs, breaks down food into nutrients.
• The nervous system, encompassing the brain, spinal cord, and nerves, coordinates the body's responses to internal and external stimuli.

An organ system is defined by the collective functions of its constituent organs, illustrating the coordination required for sustaining life. Understanding how these systems interact and depend on each other can give insights into the complexity and beauty of organismal biology.