Cells: The Smallest Structure That is Alive
• sulfur foods (onions, radishes, hemp seeds, aloe vera)
• silicon foods (cucumbers, red peppers, and other shiny-skinned produce)
• vitamin A foods (carrots, arugula, papaya)
• zinc foods (coconut, nuts and seeds)
• vitamin C (citrus fruits)
• vitamin E (avocado and olives)
The first three items on this list (atoms, molecules, and macromolecules) will be discussed further in the chapter on chemistry.
Cells are considered to be the smallest structure that is alive. They are often too small to see without the aid of a microscope. All living organisms are composed of cells. The smallest organisms are composed of a single cell; larger organisms are composed of more than one cell.
Similar kinds of cells may be arranged together to form a tissue. Tissues have specific properties and functions. For example muscle tissue is composed of muscle cells. It functions to move body components.
Two or more tissues that form a structure with a specific function is an organ. For example, the heart is an organ formed from muscle tissue, nervous tissue, connective tissue, and epithelial tissue. It functions to pump blood.
An organ system consists of two or more organs which perform a specific task. Some organ systems are: the integumentary, nervous, sensory, endocrine, skeletal, muscular, circulatory, immune, lymphatic, digestive, respiratory, excretory, and reproductive systems.
A population is an interbreeding group of organisms (the same species) that occupies a particular area.
Two or more populations form a community.
The word community refers to the organisms. The word ecosystem refers to the organisms of a community and also the nonliving environment.
All of the ecosystems on earth form the biosphere.
Living things require nutrients and energy
Organisms need nutrients and energy for their activities, growth, reproduction, and maintenance.
Chemical reactions are needed to store and release energy and to synthesize compounds needed by
• silicon foods (cucumbers, red peppers, and other shiny-skinned produce)
• vitamin A foods (carrots, arugula, papaya)
• zinc foods (coconut, nuts and seeds)
• vitamin C (citrus fruits)
• vitamin E (avocado and olives)
The first three items on this list (atoms, molecules, and macromolecules) will be discussed further in the chapter on chemistry.
Cells are considered to be the smallest structure that is alive. They are often too small to see without the aid of a microscope. All living organisms are composed of cells. The smallest organisms are composed of a single cell; larger organisms are composed of more than one cell.
Similar kinds of cells may be arranged together to form a tissue. Tissues have specific properties and functions. For example muscle tissue is composed of muscle cells. It functions to move body components.
Two or more tissues that form a structure with a specific function is an organ. For example, the heart is an organ formed from muscle tissue, nervous tissue, connective tissue, and epithelial tissue. It functions to pump blood.
An organ system consists of two or more organs which perform a specific task. Some organ systems are: the integumentary, nervous, sensory, endocrine, skeletal, muscular, circulatory, immune, lymphatic, digestive, respiratory, excretory, and reproductive systems.
A population is an interbreeding group of organisms (the same species) that occupies a particular area.
Two or more populations form a community.
The word community refers to the organisms. The word ecosystem refers to the organisms of a community and also the nonliving environment.
All of the ecosystems on earth form the biosphere.
Living things require nutrients and energy
Organisms need nutrients and energy for their activities, growth, reproduction, and maintenance.
Chemical reactions are needed to store and release energy and to synthesize compounds needed by