Earth Science: Characteristics of Earth that Sustain Life, Papers of Earth Sciences

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EARTH

SCIENCE

Characteristics of Earth that Sustain Life

Earth is one of the inner planets in the solar system. According to radiometric dating record, it is said to be 4.56 billion years old. Earth is the only place in the known universe that confirmed to host life. It is termed as “planet of life” where matter and energy continue to flow. Most of the cell’s processes requires energy from the Sun which is the main source of energy. Since Earth is a closed system, energy flows to all of its living components to continue various life processes and functions. The different forms of energy also allow the recycling of matter needed for life Figure 1a. Planet earth Figure 1b. Living things thriving on earth

What makes an Earth habitable?

The following are the factors that make our planet capable of sustaining varied life forms which thrive in the various ecosystems.

1. Temperature – This will influence how quickly atoms and molecules move. Most living things are limited to a temperature range of - 15˚C to 115˚C. Given this temperature range, H 2 O may still exist in liquid form being crucial to life. Among the other planets, only Earth’s surface has this temperature range.

2. Water – This matter dissolves and transports materials in and out of the cell. Only Earth has the right chemical materials like liquid water that could support life. 71 percent of Earth is covered with water. It is present in atmosphere, ground, freshwater lakes, oceans, and even in the polar ice caps. Water is also found in all living things. Some plants, for example, are as much as 90– 95 percent water by weight. Adult humans are about 60 percent water by weight. Water is important for the many life functions carried out by cells, tissues, and organs. It helps dissolve certain nutrients and carry them throughout an organism.

Activity 1

Direction: True or False. Write true if the statement is correct, and false if it is not. __________1. Presence of oxygen in the atmosphere has no effect on the Earth’s life forms. __________2. There is a continuous flow of energy within the Earth’s system. __________3. Earth’s water is in the form of liquid only. __________4. The energy of the sun drives all life processes on Earth. __________5. Earth is positioned in the Goldilocks zone. __________6. Earth is the third planet that has an ability to sustain life. __________7. Without the greenhouse gas earth would be frozen. __________8. Planet Earth receives only little amount of sunlight. __________9. Energy isn’t necessary to sustain life. __________10. 71% of Earth is covered with soil.

Earth and its Subsystems The planet Earth is home to varied life forms which interact continuously with the non- living components. There are four subsystems that composed the earth. These include the atmosphere, geosphere, hydrosphere and biosphere. Each of these systems, allow earth to keep itself in balance. A change in one system will affect other system. The Earth system is a closed system, a system in which there is only an exchange of heat or energy and no exchange of matter. It receives energy from the Sun but returns only some back to space. Figure 3. Earth and its subsystem

Subsystem of the Earth System

System is as a set of interconnected components that are interacting to form a unified whole. The Earth system is itself an integrated system, but can be subdivided into four main subsystems: atmosphere, hydrosphere, geosphere, and biosphere. These components are also systems in their own right and they are tightly interconnected Figure 4. Interconnection of Earth’s subsystem

Within the biosphere, living things form ecological communities based on physical surroundings of an area, known as biomes. Some examples of biomes are desert, tropical rain forest, tundra, coral reef, etc. Activity 2 Direction: Give an example of the interconnection of atmosphere, geosphere, biosphere, and hydrosphere. See the example below. (Note: you don’t need to draw) Chapter Summary Earth is the only planet in the solar system where life of plants, animals, and even microorganisms is possible. These salient features of Earth include distance from the sun, right atmospheric conditions, availability of liquid water and even water vapor and solid ice, influence of the moon, continuous flow of energy and nutrients in the system, strong magnetic field and a fitting greenhouse effect to warm the planet. There are four main subsystems of the Earth. The atmosphere is an envelope of gases protecting the surface of the planet from ultraviolet radiation from the sun. The hydrosphere comprised all the bodies of water such as ocean, sea, rivers, lakes and glaciers. The geosphere is the solid portion of earth which is consist also of the lithosphere where the crust, mantle and core are found. The biosphere is consisting of all life forms. These systems interact and are interconnected in sustaining life in varied forms.

Composition and Structures of Minerals Minerals are the building blocks of rocks. Minerals is defined by geologist as a, naturally occurring, inorganic element or compound, with a definite chemical composition, a characteristic crystalline structure, and distinct chemical properties. Minerals have to be naturally created or else they are classified as a man-made substance.

Characteristics of Minerals

1.Naturally occurring - Minerals form through natural processes, including volcanic eruptions, precipitation of a solid out of a liquid, and weathering of pre-existing minerals. Synthetic diamonds and rubies, and other substances with a specific chemical composition and structure produced by chemists, engineers, and manufacturers are not considered true minerals.

2. Solid - A true mineral must be solid at temperatures encountered at the earth’s surface. Liquids and gases are not considered minerals, they do not have a characteristic crystal structure. Ice for example ceases to exist as a mineral upon melting into liquid water.
3. Inorganic processes - Any material produced through organic activity – such as leaves, bones, peat, shell, or soft animal tissue – is not considered a mineral. Most fossils, although they were once living, have generally had their living tissues completely replaced by inorganic processes after burial; thus, they are considered to be composed of minerals as well. Almost all known minerals come from inorganic processes – activities that living things cannot carry out.
4. Chemical composition - Most minerals exist as chemical compounds composed of two or more elements. The chemical formula of salt, or halite, is NaCl. A few minerals, consist of only one type of atom such as graphite (carbon, in this case), therefore, the chemical formula for graphite is written simply as C. All minerals are defined by their chemical composition. Quartz, for example, has the chemical formula SiO2 .The gemstone amethyst is a form of quartz that is colored pale to deep purple by the presence of the impurity Iron (Fe).
5. Orderly crystalline structure - Minerals are crystalline substance which means the chemical composition of a mineral is reflected internally in a regular, repeating arrangement of atoms, called the crystal structure of the mineral.

Activity 3 Direction: Write Yes if the statement is true, otherwise, No if it is incorrect.

1. Is a mineral solid?
2. Is mineral naturally occurring crystalline materials?
3. Is a mineral has definite chemical composition?
4. Is a mineral organic substance?
5. Is a mineral an aggregate of rock?

Activity 4

Direction: Answer the following questions. 1 - 4. Give at least 4 most common elements on earth. 5 - 9. What are the characteristics of Minerals?

10. Define native element.