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Top Questions About Plants

Q: What is the difference between an animal cell and plant cell?

From Sahal in Des Moines, IA - 6th grade

A: Hi Sahal, there are three major differences between a plant cell and an animal. I will point out these aren't the only differences, but by and large the most significant. First, plant cells are autotrophs (they can create their own energy from the air and the sun!) They do this through small organelles known as chloroplasts. These chloroplasts contain many individual chlorophyll molecules which help capture energy from the sun and create sugar from carbon dioxide. This is known as photosynthesis. Humans (and all animals) are heterotrophs meaning we get our energy from eating plants or eating other animals which at some point ate a plant. Second, plant cells have a thick cell wall outside of their cell membrane. Animal cells lack this cell wall. This makes our human bodies more flexible and able to move around. A plant does not have the ability to move from wherever its roots have set into the ground. This means that on a really windy day it can't go inside. It is stuck outside to deal with the wind. One way plants have adapted to survive during a wind storm is to create these strong cell walls which give the plant a stiff rigid body. Cell walls also allow plants to grow big and tall which may help then get to more light. Third, plant cells contain one large vacuole which takes up nearly 90% of the volume cell. Animal cells also have vacuoles but are much more numerous and smaller. In a plant cell, the vacuole functions to store water and nutrients. In certain plant cells such as the xylem cells, the vacuole actually expands to make the entire cell hallow. These cells then die and are left hallow and in rows which allow the plant to suck water up from the roots.
Question answered by: Symbi Scientist, Bryon Upton


Q: What is the weirdest plant you have ever experimented on?

From Alexis in Des Moines, IA - 6th grade

A: The weirdest plant I have ever experimented on is known as Echinacea purpurea also called the purple coneflower (see photo). It is native (can be found growing in the wild) in the eastern half of the United States including here in Iowa. Native Americans have been using this plants roots and flowers as an herbal medicine and some people claim it can boost immune system, relieve pain, reduce inflammation, and have hormonal, antiviral, and antioxidant effects. As a scientist, this becomes an interesting plant to study. Basically, you have non-doctors/scientists who insist that this plant is good for them but with no understanding of how or why. The project I worked on tried to identify potential chemicals within the plant which might have medicinal properties. We worked alongside a team of doctors and scientists from the University of Iowa (I know… Cyclones and Hawkeyes working together!) who then tested these compounds on rats and then people to see if they had any positive (or negative) effect. I am not working on this project any longer, but th last I knew it was still going on and we are hopeful that some new medicines could be found based on this research.
Question answered by: Symbi Scientist, Bryon Upton


Q: Why do leaves turn colors and 'die' in autumn?

From Terry in Des Moines, IA - 6th grade

A: Leaves are normally green due to a substance called chlorophyll. Chlorophyll is a green pigment that helps plants absorb sunlight and convert sunlight and carbon dioxide into sugars and oxygen in a process called photosynthesis. Other pigments called carotenoids also help the plant/leaf absorb light and help protect chlorophyll from breaking down. Carotenoids can be yellow, orange, and brown and are found in many plants. Chlorophyll and carotenoids are made during the growing season (spring and summer), but we only see the green of the chlorophyll. As the days get shorter (fall and winter) chlorophyll production slows and then stops. We can then see the carotenoid colors. In addition, as chlorophyll production slows down, another set of pigments called anthocyanins get produced. Anthocyanins can be red, purple, or blue. Anthocyanins help protect the plant from too much light during times of low chlorophyll. Leaves fall off the tree because they are no longer supplied water by the tree and no longer produce chlorophyll. The tree removes most of the food and nutrients from the leaves in order to store for the winter.
Question answered by: Symbi Scientist, Brandon Jeffrey