I Biological organization

Look at the picture and say what you see there from the point of view of a biologist

1.1 Read the text to get the main idea, pay attention to the highlighted words

Organisms have several levels of organization. Biological organization is hierarchical: a complex organism is organized at the chemical, cellular, tissue, organ and organ system levels. All these levels together work in harmony. As a result, the organism performs its life activities.

Chemical level

The basic level of organization includes atoms and molecule. The atom, such as carbon, hydrogen, and oxygen atoms, is the smallest unit of chemical elements. Atoms combine chemically with each other to form molecules. For example carbon, hydrogen and oxygen atoms combine to form sugar molecules.

At the cellular level, many atoms and molecules come together in order to form cells. Cells are the basic unit of life. They are very small but have extraordinary functions.

Tissue level

In complex organisms, many cells which have the same function and structure come together to form tissue, such as bone cells forming bone tissue, and muscle cells forming muscle tissue.

Organ level

In the most complex organisms, tissue is organized into functional structures called organs, such as the heart, lung and kidney (animal organs). Leaves, roots and flowers are plant organs.

Organ systems or organism level

In animals, organs are organized into systems that perform particular body functions, such as the circulatory system, whose heart and blood vessels transport blood. Body systems help each other and work together. For example, the respiratory system takes in oxygen and removes carbon dioxide from the body, but cannot do this without the help of the circulatory, nervous and other body systems.

Ecological level

Population is a group of organisms of the same species living in the same geographical area at the same time, such as all students in the class. The basic unit of ecological organization is population. Several populations form a community. The community is all the populations in a given area. A community and its physics environment form the ecosystem. All of the ecosystems form the biosphere.

1.2 Answer the following questions

a How many levels does biological organization include? What are they?

b How are they interconnected?

1.3 Read the following words and give their equivalents in your native language

Hierarchical, organized, harmony, perform, organization, molecule, extraordinary, muscle, structure, heart, lung, kidney, particular, circulatory, respiratory, remove, species, physics, environment, biosphere

1.4 Match the words with their definitions

1 Hierarchical	A one of many pieces of tissue in the body that are connected to bones and which produce movement by becoming longer or shorter
2 Molecule	B a system in which things are arranged according to their importance
3 Bone	C the system of organs and tissues, including the heart, blood, blood vessels, lymph, lymphatic vessels, and lymph glands, involved in circulating blood and lymph through the body.
4 Muscle	D the smallest unit of a substance, consisting of one or more atoms
5 Lung	E one of the hard pieces that make the structure inside a person or animal
6 Kidney	F the part of the earth's environment where life exists
7 Circulatory system	G one of the small tubes that blood flows through in your body
8 Blood vessel	H one of the two organs in your body which remove waste from the blood and produce urine
9 Species	I one of the two organs inside your chest that are used for breathing
10 Ecosystem	J a group of plants or animals which share similar characteristics
11 Biosphere	K relating to the process of breathing
12 Respiratory	L all the living things in an area and the way they affect each other and the environment