What is Life
Life is defined as a characteristic that distinguishes that have signaling and self sustaining processes from those that don’t. If an organism can perform certain functions such as movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition, it is classified as a living organism. Life began from the basic building block of all living things, called cells. All organisms derived from single celled organisms. Cells are the basic building blocks of life and are found in all living things. For example, a group of cells would form a tissue, a group of tissues would form an organ, a group of organs would form an organ system an a group of organ systems would form an organism.
Different forms of life exist in the planet with human beings. Organisms like plants, animals, mammals, bacteria and many more. These organisms are divided into groups:- Animalia, Plantae, Protista, Archaea, Bacteria and Fungi.
Respiration is the process of releasing energy from glucose or any other organic material. The chemical energy in glucose is used for growth and movement. But the process of respiration in plants is different to those in animals. In respiration plants use carbon dioxide and burn the sugars they produced from photosynthesis and convert it back to energy.
Movement is another characteristic of living things which is very noticeable in most organisms. For example, animals walk. That is movement. But in some organisms such as plants it is less noticeable to see their functions as a living organism than others. For example, a sunflower plant responds to its stimuli and grows towards sunlight.
Every living organism responds to stimuli. That is a function of sensitivity. For example, if you touched something really hot, your response would be to remove your hand immediately. The pain or hotness we feel is the stimulus which is detected by the receptors in our skin which detect pain and temperature.
All living things grow...
Please join StudyMode to read the full document