This worksheet will help you understand the key characteristics that define living organisms. Use this as a guide to explore the amazing world of biology!
What Makes Something Alive?
All living things share several fundamental characteristics. Let's explore them:
1. Organization: From Cells to Ecosystems
What it means: Living things are highly organized, starting with basic units called cells. Cells are organized into tissues, tissues into organs, organs into organ systems, and organ systems into the organism itself. This organization continues on a larger scale, with populations of organisms forming communities, and communities interacting with their environment to form ecosystems.
Think about it: How does the organization of a plant, like a sunflower, differ from the organization of a human being? What are the basic building blocks of each?
2. Metabolism: Energy for Life
What it means: Living things acquire and use energy to maintain themselves, grow, and reproduce. This process is called metabolism. It involves chemical reactions that break down substances (catabolism) and build new ones (anabolism). Photosynthesis in plants and cellular respiration in animals are prime examples.
Think about it: How does a plant obtain energy? How does a human obtain energy? What are the similarities and differences in their metabolic processes?
3. Growth and Development: Changing Over Time
What it means: Living things increase in size (growth) and change in form (development) over their lifespan. This can involve cell division, cell differentiation (cells becoming specialized), and overall increase in complexity.
Think about it: How does a seed develop into a mature plant? How does a human being grow and develop from infancy to adulthood? What are some key developmental milestones?
4. Adaptation: Survival of the Fittest
What it means: Living things possess characteristics that allow them to survive and reproduce in their specific environment. These characteristics are called adaptations. Adaptations can be physical (e.g., camouflage, sharp claws) or behavioral (e.g., migration, hibernation). Adaptations are shaped by natural selection over time.
Think about it: How does a cactus adapt to survive in a desert environment? How does a polar bear adapt to survive in the Arctic? What are some examples of human adaptations?
5. Response to Stimuli: Interacting with the World
What it means: Living things react to changes in their internal or external environments. These changes are called stimuli, and the reactions are called responses. Examples include plants turning towards sunlight (phototropism), animals fleeing from predators, and humans shivering in cold temperatures.
Think about it: How does a plant respond to touch? How does a human respond to loud noise? What are some examples of responses to changes in light or temperature?
6. Reproduction: Passing on Genetic Information
What it means: Living things create new organisms similar to themselves. This process is called reproduction. It involves passing on genetic material (DNA) to offspring. Reproduction can be asexual (involving a single parent) or sexual (involving two parents).
Think about it: How do bacteria reproduce? How do humans reproduce? What are the advantages and disadvantages of asexual and sexual reproduction?
7. Homeostasis: Maintaining Balance
What it means: Living things maintain a relatively stable internal environment despite changes in their external environment. This stability is called homeostasis. It involves regulating factors such as temperature, water balance, and blood sugar levels.
Think about it: How does your body maintain a constant internal temperature? How does a plant regulate its water content? What are some mechanisms of homeostasis in different organisms?
Activity: Is it Alive?
For each of the following, determine if it is living and explain your reasoning using the characteristics of life discussed above.
- A rock
- A virus
- A tree
- A cloud
- A bacteria
This worksheet provides a foundation for understanding the fascinating world of living organisms. Remember, these characteristics work together to define life, and no single characteristic alone determines if something is alive.
