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Facts and Information About the Human Body

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Learn about the amazing systems that make bodies function.

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The elevation of unlabeled contour lines can be determined using the contour interval at the bottom of the map. The contour interval tells the vertical distance between neighboring lines. By counting the number of contours from a labeled line, and multiplying by the contour interval, you can calculate the elevation of any contour line.

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Click on the attachment to see the site

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Click on the word Attachment to see the site

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You can use this site to access books used in class and to try different practice tests in different grade levels

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This site allows you to see aspects from all our grade levels.  See me for specific ones to check out!

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Classzone.com has been retired and is no longer accessible. Because of the age of this application, the programs supported by this platform are not able to benefit from the technological improvements in accessibility, security, and HMTL5 (non-Flash) that we have incorporated into our newer programs and platforms in recent years.
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If you want to retrieve your user data from the platform that is no longer accessible, please contact techsupport@hmhco.com or 800.323.9239 and let us know that you're contacting us about user data extraction from Classzone.com.

Please note, user data extraction does not include program content.

# data[].attributes.attachment_link.description
Classzone.com has been retired and is no longer accessible. Because of the age of this application, the programs supported by this platform are not able to benefit from the technological improvements in accessibility, security, and HMTL5 (non-Flash) that we have incorporated into our newer programs and platforms in recent years.

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Not all of the light from the Sun makes it to the surface of the Earth. Even the light that does make it here is reflected and spread out. The little light that does make it here is enough for the plants of the world to survive and go through the process of photosynthesis. Light is actually energy, electromagnetic energy to be exact. When that energy gets to a green plant, all sorts of reactions can take place to store energy in the form of sugar molecules.

Remember we said that not all the energy from the Sun makes it to plants? Even when light gets to a plant, the plant doesn't use all of it. It actually uses only certain colors to make photosynthesis happen. Plants mostly absorb red and blue wavelengths. When you see a color, it is actually a color that the object does NOT absorb. In the case of green plants, they do not absorb light from the green range.

We already spoke about the structure of chloroplasts in the cells tutorials. We want to reinforce that photosynthesis happens in the chloroplast. Within this cell organelle is the chlorophyll that captures the light from the Sun. We'll talk about it in a bit, but the chloroplasts are working night and day with different jobs. The molecules are moved and converted in the area called the stroma.

Chlorophyll is the magic compound that can grab that sunlight and start the whole process. Chlorophyll is actually quite a varied compound. There are four (4) types: a, b, c, and d. Chlorophyll can also be found in many microorganisms and even some prokaryotic cells. However, as far as plants are concerned, the chlorophyll is found in the chloroplasts. The other big molecules are water (H ₂O), carbon dioxide (CO ₂), oxygen (O ₂) and glucose (C ₆H ₁₂O ₆). Carbon dioxide and water combine with light to create oxygen and glucose. That glucose is used in various forms by every creature on the planet. Animal cells require oxygen to survive. Animal cells need an aerobic environment (one with oxygen).

The whole process doesn't happen all at one time. The process of photosynthesis is divided into two main parts. The first part is called the light dependent reaction. This reaction happens when the light energy is captured and pushed into a chemical called ATP. The second part of the process happens when the ATP is used to make glucose (the Calvin Cycle). That second part is called the light independent reaction.

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Not all of the light from the Sun makes it to the surface of the Earth. Even the light that does make it here is reflected and spread out. The little light that does make it here is enough for the plants of the world to survive and go through the process of photosynthesis.