1. Characteristics of Living Things

2. Key Ideas
5.2a – Homeostasis in an organism is constantly threatened. Failure to respond effectively can result in disease or death.

3. 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

4. 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

5. 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

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

7. Life Processes

8. 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

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

10. Transport
Transport – process by which substances enter and leave cells and become distributed within the cell
Transport involves both 
Absorption – process by which end products of digestion and other dissolved substances are taken into the cells and fluids of the organism
Circulation – distribution of materials within an organism
Usable materials enter the cells directly from the environment
Waste materials leave the cell and into the environment
Multicellular animals use a circulatory system

11. Multicellular plants use structures to transport substances from roots to the leave

12. Multicellular animals use a circulatory system

13. 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.

14. 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 organisms

15. 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.
Ingestion – taking in of food from the environment
Digestion – breakdown of complex food materials into simpler forms that an organism can use

16. 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

18. 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

19. 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 molecule of glucose
Anaerobic Respiration – breakdown of sugar into carbon dioxide and water without oxygen and yields less ATP for a molecule of glucose

20. 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!

21. 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

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

23. 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 the offspring is not identical to either parent

24. 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