EXCRETION

* the life function that involves the removal of the cellular waste products (not digested food being egested) of an organism.
* metabolic activities are chemical reactions that produce waste produced.
* these products can be TOXIC (poisonous)

* animals must get rid of them!
* plants can sometimes store them in special, sealed off vacuoles.
* non-toxic wastes can be either retained, released, or recycled in other reactions

  1. aerobic respiration produces water and carbon dioxide
  2. anaerobic respiration produces lactic acid or alchohol and carbon dioxide
  3. dehydration synthesis produces water
  4. protein metabolism produces nitrogenous wastes
  5. other metabolic processes can produce salts, oils, etc.

* nitrogenous wastes are produced when excess amino acids are utilized by cellular respiration; toxicity (how poisonous) varies from:

EXTREMELY TOXIC ---- AMMONIA

LESS TOXIC ---- UREA

NON-TOXIC ---- URIC ACID


ADAPTATIONS FOR EXCRETION
organisms display various adaptations for excretion that depend on:

1. The metabolic activities of that organism.

2. The environment in which it lives in.

I. Protists
* most protists do not have any special structures for excretion
* the cell membrane accomplishes excretion by diffusion

* digested food is egested through "used" food vacuoles
* excess water is removed by the 'squeezing' of the contractile vacuole

A) Freshwater Protozoans
* the wastes of the ameba and paramecium (to name a few) such as carbon dioxide, ammonia, and mineral salts are diffused right into the watery environment

B) Algae
* plant-like protists
* carries out photosynthesis (making food from light)
* some wastes can be recycled!

CO2 + H2O goes into PHOTOSYNTHESIS and C6H12O6 + O2 comes out and...

C6H12O6 + O2 goes into AEROBIC RESPIRATION and CO2 + H2O comes out.

NATURAL RECYCLING OCCURS!!!


II. Plants
* like algae, plants recycle the products of photosynthesis and aerobic respiration
* excess gases leave through openings in the leaf (stomates) and in the stem (lenticels)
* some toxic wastes are safely sealed off in vacuoles

Excretion and Locomotion

LOCOMOTION

* the ability of an organism to move (by itself) from place to place
* locomotion increased the probability of survival among animals and many protists

ADVANTAGES OF LOCOMOTION

1) increased opportunities to locate food

2) increased ability to seek shelter

3) increased ability to avoid from predators

4) increased ability to move from toxic wastes

5) increased opportunities to locate mates


ADAPTATIONS FOR LOCOMOTION

I. Protists

A) Protozoans

1) cilia: short hair-like projections of the cytoplasm that are common to paramecia

2) pseudopods: cytoplasmic extensions resembling "feet" which enable amebas to move

3) flagella: a long, whip-like structure found in certain algae and sometimes protozoans

II. Plants

PLANTS DO NOT MOVE
THEY ARE CALLED SESSILE

(when have you ever seen a plant move from place to place by itself?)

Excretion and Locomotion

find out what is animal locomotion
what is an advantage of being able to move around?
look at these single cell critters move around
HOMER the horse!