Forces and Motion in Organisms.pdf

Have you heard of anechoic chambers? Informally called the “quietest places on Earth,” these rooms have special padded walls that eliminate 99.9 percent of background noise. They are used to test electronics and other products, but a person standing alone in one would be flooded by the sounds coming...

Have you heard of anechoic chambers? Informally called the “quietest places on Earth,” these rooms have special padded walls that eliminate 99.9 percent of background noise. They are used to test electronics and other products, but a person standing alone in one would be flooded by the sounds coming from their own body. Some people report hearing the noise of their pulse and blood rushing through their circulatory system. We typically overlook the forces and motion at work in our bodies and within other living things. Here, we’ll examine them more closely! We think of plants as stationary organisms, but they have forces within their cells that influence movement and growth. An example of an internal plant force is known as geotropism. If an acorn is planted in the pitch-black ground, how does the budding oak tree know which way to grow? Well, once the shoot inside of the acorn breaks through the shell, the hormone auxin tells the plant which way gravity is pulling. Auxin passes between plant cells and settles in the part of the shoot facing down. The chemical causes these cells to grow faster against the force of gravity. Since the plant is growing away from the center of the earth, it eventually emerges from the soil and toward sunlight. You may have seen plants in the garden wither on dry summer days. This is due to another force within plants: turgor pressure. We all know that plants need water to grow. The water taken in through the roots passes from cell to cell, carrying important nutrients. When sufficient water is taken in, each plant cell fills up with water exerting pressure on the rigid cell wall (a tough, outer layer of each plant cell). This pressure can build up strong enough for a plant to break through an acorn shell, pavement, and even rocks. When plants do not have enough water, their cells become flimsy, and the plant itself becomes limp. What about forces inside of the human body that can be heard inside an anechoic chamber? There are several processes that occur within us that are involuntary. The “noisiest” would most likely be blood circulation and digestion. A human’s four-chambered heart constantly pumps blood throughout a highway of blood vessels. This blood carries vital oxygen to our muscles and organs, picks up carbon dioxide waste, and circulates important chemical signals. Another noisy region in humans is the digestive tract. After we chew and swallow our food, it is passed through our digestive tract by steady muscle contractions. We may not notice these forces inside of us, but they are responsible for our movement and ability to meet our life needs. Image: Mathieu Rodriguez - Own work, CC BY-SA 3.0, commons.wikimedia.org © Kesler Science, 2020 Have you heard of anechoic chambers? They are known informally as the “quietest places on Earth.” These special rooms have exceptionally padded walls that cancel out almost all background noise. They are used to test electronics and other products. A person standing alone in one of these super-silent rooms would clearly hear sounds coming from their own body. Some people hear the noise of their pulse and moving blood. We typically overlook the forces and motion that take place in our bodies and other living things. Here, we’ll look at those things more closely. Plants have forces inside their cells that affect their ability to grow and move. An example of force inside plants is geotropism. If an acorn is planted in the ground, how does it know which way is up? Once the shoot inside of the acorn breaks through the shell, a hormone called auxin tells the plant which way gravity is pulling. The plant grows away from the pull of gravity. It eventually breaks out of the soil and toward sunlight. Now, let’s look at another force inside plants. You may have seen plants in the garden droop on dry summer days. This is due to another force within plants: turgor pressure. We all know that plants need water to grow. The water taken in through the roots passes from cell to cell carrying important nutrients. Each plant cell can fill up with water. When enough water comes in, pressure builds on the cell wall (a tough, outer layer of each plant cell) and helps the plant stand up. This pressure can build up strong enough for a plant to break through an acorn shell, pavement, and even rocks. When plants do not have enough water, their cells become flimsy, and the plant droops. What about forces inside of the human body that can be heard inside an anechoic chamber? Processes occur within us that are involuntary. The “noisiest” would most likely be blood circulation and digestion. Our four-chambered heart constantly pumps blood throughout our blood vessels. This blood carries oxygen to our muscles and organs, picks up carbon dioxide waste, and moves important chemical signals. Another noisy part of the body is the digestive system. After we chew and swallow our food, steady muscle contractions move it through our digestive system. We may not notice the forces inside of us, but they are responsible for our movement and ability to meet our life needs. Image: Mathieu Rodriguez - Own work, CC BY-SA 3.0, commons.wikimedia.org © Kesler Science, 2020 Comprehension QUESTIONS Answer the questions below based on the article about forces and motion in organisms. 1. What is geotropism, and how does it work? ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 2. You forget to water your houseplant, and it begins to wither. Explain why this is happening, using the term “turgor pressure.” ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 3. Give an example of forces that cause movement inside the human body. ____________________________________________________________________ ____________________________________________________________________ 4. What are some ways that doctors can hear movement inside the human body? ____________________________________________________________________ ____________________________________________________________________ 5. The ability of plants to turn their leaves toward the sun is called “phototropism.” Why is it important for plant leaves to face the sunlight? ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ Mini-Project: TURGOR PRESSURE DIRECTIONS: The article states that “turgor pressure” allows plants to grow through pavement and rock. Explore your neighborhood or school grounds. Take a photo or make a sketch of this impressive show of plant strength. Explain your picture or sketch by describing how water is related to this phenomenon. © Kesler Science, 2020 TURGOR PRESSURE DIRECTIONS: The article states that “turgor pressure” allows plants to grow through pavement and rock. Explore your neighborhood or school grounds. Take a photo or make a sketch of this impressive show of plant strength. Explain your picture or sketch by describing how water is related to this phenomenon. __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ __________________________________________________________ © Kesler Science, 2020 ANSWER KEY 1. What is geotropism, and how does it work? Geotropism refers to plants’ growth in response to the pull of gravity. The plant hormone auxin builds up and directs the plant to grow opposite the pull of gravity. 2. You forget to water your houseplant, and it begins to wither. Explain why this is happening, using the term “turgor pressure.” Plants use the water that fills their cells to provide structure and support. This water pressure is called turgor pressure. The houseplant is withering because the plant cells don’t have enough water inside to keep them firm and upright. 3. Give an example of forces that cause movement inside the human body. Students can describe the flow of blood through the circulatory system or food through muscle contractions in the digestive system. Students are welcome to look up other examples of forces/movement besides those listed in the article. (For example, how are messages sent through the nervous system?) 4. What are some ways that doctors can hear movement inside the human body? Doctors can use a stethoscope to listen to heart and lungs. It can also be used to hear blood pressure. 5. The ability of plants to turn toward the sun is called “phototropism.” Why is it important for plant leaves to face the sunlight? Plants need sunlight to perform photosynthesis, which provides them with food.