Unit C Lesson 4: Substances Essential for Life
Completion requirements
Unit C Lesson 4: Substances Essential for Life |
Learning Targets |
Big Question: How do organisms take in substances they need?
Obtaining nutrients and removing waste is a fundamental process for all living things.
Obtaining nutrients and removing waste is a fundamental process for all living things.
At the end of this inquiry, you should be able to answer the following questions:
- What is diffusion?
- What is osmosis?
- What is the difference between active and passive transport?
- How are nutrients ingested and absorbed by animals?
- What is a substrate?
Pages 204 to 209 in your textbook will help you answer these questions about substances essential for life.
Introduction
Living organisms need to take in many substances to live. In this lesson, you will learn of the various ways nutrients enter plants and animals.
Lesson 4 has four parts:
Plants take in substances through both roots and leaves. Leaves take in mostly gases from the atmosphere while the roots take in minerals and larger molecules. Plants use three methods to absorb nutrients into their roots: diffusion, osmosis, and active transport.
Lesson 4 has four parts:
- Passive Transport
- Active Transport
- Ingestion and Absorption of Materials by Animals
- Substrates
Plants take in substances through both roots and leaves. Leaves take in mostly gases from the atmosphere while the roots take in minerals and larger molecules. Plants use three methods to absorb nutrients into their roots: diffusion, osmosis, and active transport.
Diffusion is the movement of a substance (such as an atom, ion, or molecule) from a region of high concentration to a region of low concentration. This is called moving down a concentration gradient.
Small minerals flow easily into the roots of plants through diffusion. As long as there is a concentration difference (that is, there are more minerals in the soil than in the plant) and the substance can pass through any membranes that may be present, diffusion occurs. Diffusion also occurs in the lungs, when oxygen and carbon dioxide diffuse in and out of the small alveoli when we inhale and exhale during breathing.
Osmosis is a special type of diffusion in which water molecules move across a membrane from an area where there are more water molecules to an area where there are fewer water molecules. As long as there is a higher concentration of water outside the root than inside, water will move into the root.
Figure 1 – In diffusion, particles move from high concentration to lower concentration. (Science in Action 9, page 204)
Figure 2 – Osmosis is the diffusion of water through a semipermable membrane.
In osmosis, water passes through the “gaps” in the membrane. The larger particles are unable to pass through the membrane because of their large size. The membrane is said to be semi-permeable, which means that it allows only certain substances
in and out of the cell.
Watch
Watch this video about diffusion and osmosis.
Passive Transport
Oxygen and water enter and exit the plant cells with no energy. This is called passive transport. Passive transport works through diffusion, a natural spreading of chemicals through a liquid or gas. Both diffusion and osmosis are examples of passive transport because no energy is required for the particles to move from one place to another.
Interactive
Passive Transport
- The BrainPOP video, "Passive Transport", demonstrates the movement of molecules through diffusion and osmosis.
Click here
to watch the video. You will need a username and password to access the video.
- Username: 0099
- Password: students
-
Click here
to complete the BrainPOP quiz on Passive Transport. Remember to check your answers at the end!
Active Transport
Active transport is the movement of substances through a membrane from low concentration to high concentration. Because the substances are moving against their concentration gradient, energy is required.
During active transport, plants use energy to increase the concentration of minerals and organic substances inside the cells of their roots. The movement of minerals occurs from an area of lower concentration (soil) to one of higher concentration (plant).
Active transport is the opposite of passive transport because the substances are moving against their concentration gradient so energy is required.
Active transport is the movement of substances through a membrane from low concentration to high concentration. Because the substances are moving against their concentration gradient, energy is required.
During active transport, plants use energy to increase the concentration of minerals and organic substances inside the cells of their roots. The movement of minerals occurs from an area of lower concentration (soil) to one of higher concentration (plant).
Active transport is the opposite of passive transport because the substances are moving against their concentration gradient so energy is required.
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Passive Transport (diffusion and osmosis)
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Active Transport
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high concentration → low concentration
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low concentration → high concentration
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no extra energy is required
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requires energy
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occurs in plant and animal cells
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occurs in plant and animal cells
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Interactive
Active Transport
- Click here to watch the BrainPOP video to learn more about active transport in plant and animal cells.
You will need a username and password to access the video.
- Username: 0099
- Password: students
-
Click here
to Complete the BrainPOP quiz on Active Transport. Remember to check your answers at the end!
Watch
Watch the following video carefully, it provides and excellent overview of how living things take in substances.
Ingestion
and Absorption of Materials by Animals
The human body, like that of other animals, needs more than 25 elements to live. They are needed in many forms, inorganic and organic. The main way we get these substances into our bodies is by eating them through a process called ingestion.
Digestion is the breakdown of food into smaller components that can be more easily absorbed by the body. After food is ingested, it is broken down by the digestive system.
Mechanical digestion, the physical breaking down of food, begins in the mouth where the chewing breaks food into small pieces. Chemical digestion starts in the mouth with the help of saliva and continues as the food passes through the remainder of the digestive system.
Enzymes break food into particles that the body can absorb such as glucose and amino acids. When the particles are small enough, and in the correct form, they are passed into the circulatory system to be carried to all parts of the body. Then, the molecules are used by cells or stored.
Some ingested and absorbed particles are harmful, and the body attempts to break them down to less harmful substances that can be excreted.
The human body, like that of other animals, needs more than 25 elements to live. They are needed in many forms, inorganic and organic. The main way we get these substances into our bodies is by eating them through a process called ingestion.
Digestion is the breakdown of food into smaller components that can be more easily absorbed by the body. After food is ingested, it is broken down by the digestive system.
Mechanical digestion, the physical breaking down of food, begins in the mouth where the chewing breaks food into small pieces. Chemical digestion starts in the mouth with the help of saliva and continues as the food passes through the remainder of the digestive system.
Enzymes break food into particles that the body can absorb such as glucose and amino acids. When the particles are small enough, and in the correct form, they are passed into the circulatory system to be carried to all parts of the body. Then, the molecules are used by cells or stored.
Some ingested and absorbed particles are harmful, and the body attempts to break them down to less harmful substances that can be excreted.
Check Your Understanding
Digestive System
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Click here
to watch the BrainPOP video "Digestive System" to learn about more digestion in humans. You will need a username and password to access the video.
- Username: 0099
- Password: students
- Click here to complete the BrainPOP quiz on Digestion. Remember to check your answers at the end!
Substrates
A substrate is the type of material an organism lives on. The easiest examples of substrates are organisms like plants, molds, and fungi which do not move. The substrate can be a source of support or food.
The substrate of a potato plant would be the soil it grows in. Mold will grow on a substrate like bread, where it finds nutrients. Even animals have substrates. Sea anemones, for example, anchor themselves to rocks in rough water. They pick
nutrients from the moving water as they stay attached to the rock.
The leaf is a substrate for the caterpillar. The leaf is a material on which the caterpillar moves on.
Mold is an organism that lives on and obtains nutrients from its substrate.
Moss is living on a rock. The rock is the substrate. Moss is an example of an organism that attaches itself to its substrate.