A) Life Functions

Biology= the study of life

organism- a living thing

Scientists have been unable to agree on a single definition that characterizes life.

LIFE FUNCTIONS: (in all organisms including humans)

1. Nutrition- the obtaining and processing of materials by an organism for its use

(a.) ingestion- food intake by an organism

(b.) digestion- breakdown of complex foods to simpler foods by an organism

2. Circulation - distribution of materials within an organism

3. Movement- change in position by a living thing

4. Respiration- process used by organisms to release the energy in their food

(ex. oxygen + glucose yields carbon dioxide + water + ENERGY)

** The energy released in respiration is needed to maintain life functions.

5. Synthesis- combining simpler chemical substances to form more complex ones

(ex. starches from simple sugars)

6. Excretion- the removal of cellular waste products

7. Regulation (coordination)

- the control of the various activities of an organism (mostly involves the nervous system and endocrine glands in complex organisms)

8. growth- increase in living matter by increasing cell size or numbers

9. reproduction- ability of living things to form more of their own kind

** Not needed for organism survival--but necessary for the survival of the species.

10. immunity -- the ability of an organism to resist disease causing organisms and foreign invaders

Metabolism- the sum total of all life processes needed to sustain life

Homeostasis- the maintenance of an internal stable environment by an organism (steady state)

A disruption in any organism system will result in a corresponding disruption of homeostasis.

[Some Examples of Maintaining Homeostasis in Living Things]

1.) environmental temp increases ----> more sweating ---> more evaporation --> cools down body

2.) Blood sugar regulation

insulin -- a hormone (chemical messenger) produced by the pancreas and carried through the blood

-- lowers blood sugar 2 major ways:

a.) Takes glucose into our cells to be used as fuel in cell respiration from our blood

b.) Converts excess glucose to the glycogen (animal starch) and stores it in our liver and muscles

glucagon -- another pancreas hormone which can convert glycogen back to glucose if our sugar level is too low

The failure to maintain blood glucose homeostasis results in diabetes.

3.) Plant leaf regulation of water balance inside them.

stomata -- microscopic holes in a leaf which allow for exchange of water vapor out of the plant

(and other gases in and out of the leaf)

guard cells -- open and close the stomata

Changes in the stomata controlled by guard cells regulate the rate of water loss and gas exchange by many plants.