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7/31/2019 Extra Page in Summative for Science

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Stars vs. Planets

The basic difference between a star and a planet is that a star emits light produced by a nuclear

reaction in its core, whereas a planet only shines by reflected light. Not all objects in the

universe that don't produce their own light are planets however. It's a gray area, as we'll see.

StarA self-luminous object that shines through the

release of energy produced by nuclear reactions

at its core.

Planet

A planet is a spherical ball of rock

and/or gas that orbits a star.

Difference between Rotation and Revolution

Rotation is the movement of the Earth on its axis. It makes us experience night and day. It takes

about 24 hours to complete one rotation.

Revolution is the trip the Earth takes in its orbit around the sun. It takes a year to complete one

revolution.


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Nitrogen Cycle

Nitrogen is the major component of earth's atmosphere. It enters the food chain by means of

nitrogen-fixing bacteria and algae in the soil. This nitrogen which has been 'fixed' is now

available for plants to absorb. These types of bacteria form a symbiotic relationship with

legumes--these types of plants are very useful because the nitrogen fixation enriches the soil

and acts as a 'natural' fertilizer. The nitrogen-fixing bacteria form nitrates out of theatmospheric nitrogen which can be taken up and dissolved in soil water by the roots of plants.

Then, the nitrates are incorporated by the plants to form proteins, which can then be spread

through the food chain. When organisms excrete wastes, nitrogen is released into the

environment. Also, whenever an organism dies, decomposers break down the corpse into

nitrogen in the form of ammonia. This nitrogen can then be used again by nitrifying bacteria to

fix nitrogen for the plants.

Human Impact

Humans contribute by using nitrogen-containing fertilizers in agriculture. Under conditions in

which agricultural plants have access to as much water as they require, their productivity is

usually constrained by the rate at which they can obtain nitrogen in available forms, particularly

nitrate, and sometimes ammonium. Under such conditions, farmers attempt to increase the

availability of these nutrients, usually by applying fertilizers.

Carbon Cycle

All living things are made of carbon. Carbon is also a part of the ocean, air, and even rocks.

Because the Earth is a dynamic place, carbon does not stay still. It is on the move!

In the atmosphere, carbon is attached to some oxygen in a gas called carbon dioxide.

Plants use carbon dioxide and sunlight to make their own food and grow. The carbon becomes

part of the plant. Plants that die and are buried may turn into fossil fuels made of carbon like

coal and oil over millions of years. When humans burn fossil fuels, most of the carbon quicklyenters the atmosphere as carbon dioxide.

Human Impact

Humans impact the carbon cycle during the combustion of any type of fossil fuel, which may

include oil, coal, or natural gas. Fossil Fuels were formed very long ago from plant or animal

remains that were buried, compressed, and transformed into oil, coal, or natural gas. The

carbon is said to be "fixed" in place and is essentially locked out of the natural carbon cycle.

Humans intervene during by burning the fossil fuels. During combustion in the presence of air

(oxygen), carbon dioxide and water molecules are released into the atmosphere.

Photosynthesis and Cellular Respiration

Photosynthesis is the process where green plants use sunlight, carbon dioxide, and water to

make food and oxygen.Cellular respiration is what cells do to break up sugars into a form that

the cell can use as energy.


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Water Cycle

When water falls back to earth as

precipitation, it may fall back in the

oceans, lakes or rivers or it may end

up on land. When it ends up on

land, it will either soak into theearth and become part of the

ground water that plants and

animals use to drink or it may run

over the soil and collect in the

oceans, lakes or rivers where the

cycle starts all over again.

Evaporation:

Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into

vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air.

Transpiration:

Transpiration is the process by which plants lose water out of their leaves. Transpiration gives

evaporation a bit of a hand in getting the water vapor back up into the air.

Condensation:

Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called

condensation.

Precipitation:

Precipitation occurs when so much water has condensed that the air cannot hold it anymore.

The clouds get heavy and water falls back to the earth in the form of rain, hail, sleet or snow.

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