Organs work together to form organ systems. In this class, we will be focusing on how cells function, so we will be concentrating on biological molecules, how they make up cells, and how those cells function. Organisms respond to diverse stimuli. For example, plants can bend toward a source of light, climb on fences and walls, or respond to touch Figure 2.
Even tiny bacteria can move toward or away from chemicals a process called chemotaxis or light phototaxis. Single-celled organisms reproduce by first duplicating their DNA, and then dividing it equally as the cell prepares to divide to form two new cells.
Multicellular organisms often produce specialized reproductive germline reproductive cells that will form new individuals. DNA contains the instructions to produce all the physical traits for the organism. This means that because parents and offspring share DNA ensures that the offspring will belong to the same species and will have similar characteristics, such as size and shape.
For example, a human grows from a baby into an adult and goes through developmental processes such as puberty. Organisms grow and develop following specific instructions coded for by their genes DNA. In order to function properly, cells need to have appropriate conditions such as proper temperature, pH, and appropriate concentration of diverse chemicals.
These conditions may, however, change from one moment to the next. For example, an organism needs to regulate body temperature through a process known as thermoregulation. Second, living things must have metabolism. This includes all the biochemical reactions that take place in something that is alive. The third property is homeostasis. That means that living things regulate the conditions inside their bodies.
Living things also experience growth. They reproduce in some way, although this can take many forms. Living things must give response to changes in their environment. Finally, the last property of life is evolution. Living things must be able to change over time.
Not all experts agree with these properties of life. Consider the mule. However, most people would consider the mule to be alive. Still, the properties of life provide a starting point for understanding what makes something alive. There are still many questions to answer. For example, what about viruses? Experts disagree over whether they are living things. Others disagree, as viruses do have many of the other properties of life. How about life on other planets?
Will it look like life on Earth? Most likely not. That means those searching for alien life have to keep open minds about what makes something alive.
Our understanding of this will probably continue to develop as humans explore deeper into the universe. What do you think? Would you classify viruses as living things? Do the properties of life seem right to you? What do you think alien life could look like? Human beings are still searching for solid answers to these questions and many more. Do you LIVE to learn? Find an adult who can help you with one or more of these fun learning activities!
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Thanks for your patience. Earthworms hatch from eggs and can grow up to a metre or more in length! Some earthworms are also able to regrow small parts of their body that have been lost or injured. Earthworms have both sperm and eggs within their bodies they are hermaphrodites but they cannot self-fertilise and need to mate with another individual. After mating, a cocoon containing the fertilised eggs is deposited in the soil.
Earthworm nutrition comes from a variety of sources, depending on their species. Food types include manure, compost, plant material, fungi, microorganisms and decaying animals. They take in food through their mouths. Based on the information above, we can confidently categorise earthworms as living things as they carry out all seven life processes. It is now possible to classify them further into a series of hierarchical categories: kingdom, phylum, class, order, family, genus and species.
Classifying living things into these categories is an important way for scientists to show how living things are related to each other. Most scientists classify living things into one of the following six kingdoms. What did you decide? Sometimes people are surprised to find out that earthworms are actually animals — the same kingdom as humans, cats, dogs, dolphins and spiders!
Just as living things share a set of common characteristics, animals have key characteristics that can help you to decide whether a living thing is an animal or not.
Scientists need scientific vocabulary to communicate effectively. At an even more fundamental level, scientific language actually helps shape ideas and provides the means for constructing scientific understandings and explanations.
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