Characteristics of Living Things

1. Characteristics of Living Things

2. Biology • Biology – Study of living things • More than 1 million different kinds of living things • All living things are similar in many ways • Organism = Living thing

3. Signs of Life A living organism will show all of the following Signs of Life: • Highly organized and contain many complex chemical substances • Made up of one or many cells, which are the smallest unit that can be said to be alive • Living things use energy • Have definite form and limited size • Limited life span

4. Signs of Life A living organism will show all of the following Signs of Life: • Living things grow • Respond to changes in the environment • Able to reproduce • Evolve or change, over long periods of time. This is a characteristic of groups of organisms, not of individuals

5. Non-Living Things • Non-living things may show one or a few of the Signs of Life, but they never show all of them

6. Life Processes

7. Life Processes • Life processes are necessary for maintaining a fairly constant environment within an organism, in spite of the constantly changing external environment • All living things must maintain homeostasis • Homeostasis – The condition of a stable (balanced) internal environment in an organism • Dynamic Equilibrium – The body stays balanced by taking action whenever the balance is disturbed • Metabolism – all chemical reactions occurring within the cells of an organism • Regulation – all of the activities that help maintain an organism’s homeostasis

8. Life Processes • To maintain homeostasis, organisms carry out the same basic life functions: • Regulation • Transport • Nutrition • Excretion • Respiration • Growth • Synthesis • Reproduction

9. Transport • Transport – process by which substances enter and leave cells and become distributed within the cell • Usable materials enter the cells directly from the environment • Waste materials leave the cell and into the environment • Multicellular animalsuse a circulatory system • Multicellular plantsuse structures to transport substances from roots to the leave

10. Transport • Diffusion – movement of molecules from high concentration to low concentration. It requires no energy (passive transport). • Active Transport – requires the use of energy, usually moving molecules from a low concentration to high concentration (against the flow of diffusion) • Osmosis – diffusion of water into or out of the cell. If water diffuses into the cell, the cell swells (gets larger) and may burst. If it loses water (being put in salt water for example) it will shrivel up.

11. Nutrition • Nutrition – when organisms take materials from its external environment and changes them into forms it can use • Nutrients – substances that an organism needs for energy, growth, repair or maintenance • Types of Nutrition: • Producers (Autotrophs) – make their own food • Consumers (heterotrophs) – cannot make their own nutrients so they obtain ready made nutrients by eating other organism

12. Nutrition • Photosynthesis is carried out by plants, algae and blue-green bacteria (autotrophs). • It takes the radiant energy of the sun and puts it in the bonds of sugar molecules • Photosynthesis formula: • 6 CO2 + 6 H2O  C6H12O6 + 6 O2 • Photosynthesis occurs in the chloroplast of plant cells • Photosynthesis only stores energy in food (glucose). We need respiration to get the energy out of the food.

13. Nutrition • Plants have stomates (holes) in their leaves that let them exchange the gasses used in photosynthesis • Guard cells open and close the stomates to keep the plant from dehydrating • Guard cells only protect plants from water lose • Xylem and phloem carry food and water through a plant

16. Excretion • Excretion – removal of the waste from the organism’s body • Organisms produce wastes substances that cannot use and that may be harmful if accumulated in the body • Waste are products of many chemical reactions that occur in cells

17. Respiration • Respiration – process that takes energy from sugar molecules and places it in molecules of ATP • ATP is the energy source of all living things • Organisms obtain their energy by releasing the chemical energy stored in nutrients • Aerobic Respiration – breakdown of sugar into carbon dioxide and water that requires oxygen and yields more ATP for a molecules of glucose • Anaerobic Respiration – breakdown of sugar into carbon dioxide and water without oxygen and yields less ATP for a molecule of glucose

18. Respiration • When humans are forced to get energy from anaerobic respiration, we produce lactic acid that damages muscles (the burn you feel during exercise) • Photosynthesis and aerobic respiration are opposite reactions!

19. Growth • Growth – process by which living organisms increase by size • Cellular Specialization – process that involves different cells becoming specialized for different functions • Organisms can repair and replace worn-out parts

20. Synthesis • Synthesis – ability to combine simple substance chemically to form more complex substances • Assimilation – incorporation of materials into the organism's body

21. Reproduction • Reproduction – process by which living things produce new organisms of their own kind • Types of Reproduction: • Asexual – single individual produces an identical offspring • Sexual – two parents and offspring are not identical to either parent

22. Metabolism • Metabolism – all chemical reactions occurring within the cells of an organism • Build complex substances from simpler ones and processes that break down complex substances into simpler ones • Releases and uses energy