Perhaps the study of chemical reactions is not a central theme of biology, but of chemistry.

Terms in this set (9) Biology is the study of life; examines how living things interact, how systems function and how they function at a molecular level.

The word biology is derived from the greek words /bios/ meaning /life/ and /logos/ meaning /study/ and is defined as the science of life and living organisms. An organism is a living entity consisting of one cell e.g. bacteria, or several cells e.g. animals, plants and fungi.

Living organisms must take in *energy* via food, nutrients, or sunlight in order to carry out cellular processes. The transport, synthesis, and breakdown of nutrients and molecules in a cell require the use of energy.

The five central themes of biology are structure and function of cells, interactions between organisms, homeostasis, reproduction and genetics, and evolution.

To be classified as a living thing, an object must have all six of the following characteristics:

• It responds to the environment.
• It grows and develops.
• It produces offspring.
• It maintains homeostasis.
• It has complex chemistry.
• It consists of cells.

seven characteristics

An object has identity (each object is a distinct individual). An object has state (it has various properties, which might change). An object has behavior (it can do things and can have things done to it).

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Answer Expert Verified Dentists need to know about the mouth and teeth. Thse involve learning about the human body, so is therefore a branch of biology. Zoology is the study of animals, and they are living creatures, meaning that this is a branch of biology.

In general, biologists study the structure, function, growth, origin, evolution and distribution of living organisms. Biology is important because it helps us understand how living things work and how they function and interact on multiple levels, according to the Encyclopedia Britannica.

The difference between the cellular make-up of a living organism and aluminum can is the ability to use energy.

Cellular organisms are divided in two groups known as prokaryotes and eukaryotes. The genetic material, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are arranged into structures called chromosomes. Some cells have other structures such as cell wall, pili, and flagella.

Bacteria are single celled microbes. The cell structure is simpler than that of other organisms as there is no nucleus or membrane bound organelles.

cell, in biology, the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell is often a complete organism in itself, such as a bacterium or yeast. Other cells acquire specialized functions as they mature.

They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells also contain the body’s hereditary material and can make copies of themselves. Cells have many parts, each with a different function.

Cells are of two types: eukaryotic, which contain a nucleus, and prokaryotic, which do not. Prokaryotes are single-celled organisms, while eukaryotes can be either single-celled or multicellular.

The Four Main Types of Cells

• Epithelial Cells. These cells are tightly attached to one another.
• Nerve Cells. These cells are specialized for communication.
• Muscle Cells. These cells are specialized for contraction.
• Connective Tissue Cells.

Stem Cells

Red blood cells

Human cells are eukaryotic cells.

The human body is a combination of both prokaryotes and eukaryotes. The human body contains a large number of prokaryotes. In the real sense of it, the number of prokaryotes in the human body exceeds the number of human cells present in the body. Prokaryotes do not only live in the human body.

Human cells only have a cell membrane. The cell wall is primarily made of cellulose, which is composed of glucose monomers. As the outermost layer of the cell, it has many important functions. It prevents the plasma membrane from bursting as a result of water uptake and it determines the overall cell shape and texture.

Eukaryotic cells are found in plants, animals, fungi, and protists. They generally have a nucleus—an organelle surrounded by a membrane called the nuclear envelope—where DNA is stored. There are a few exceptions to this generalization, such as human red blood cells, which don’t have a nucleus when mature.

Like red blood cells, platelets are derived from myeloid stem cells. Some of these stem cells develop into megakaryoblasts, which give rise to cells called megakaryocytes in the bone marrow. Because they are not cells, platelets don’t have their own nuclei.

Most prokaryotes carry a small amount of genetic material in the form of a single molecule, or chromosome, of circular DNA. The DNA in prokaryotes is contained in a central area of the cell called the nucleoid, which is not surrounded by a nuclear membrane.

Red blood cells have adapted this characteristic (no nucleus) for several reasons. It simply allows the red blood cell to have more hemoglobin. Therefore, it allows RBC to transfer more oxygen. Lack of nucleus in RBC also allows the cell to have an unique bi concave shape that helps with diffusion.

Suspended in the watery plasma are seven types of cells and cell fragments.

• red blood cells (RBCs) or erythrocytes.
• platelets or thrombocytes.
• five kinds of white blood cells (WBCs) or leukocytes. Three kinds of granulocytes. neutrophils. eosinophils. basophils. Two kinds of leukocytes without granules in their cytoplasm.

Specifically, mature red blood cells and cornified cells in the skin, hair, and nails contain no nucleus. Mature hair cells do not contain any nuclear DNA.

Unlike red and white blood cells, platelets are not actually cells but rather small fragments of cells. Platelets help the blood clotting process (or coagulation) by gathering at the site of an injury, sticking to the lining of the injured blood vessel, and forming a platform on which blood coagulation can occur.