BIO 7:  Lecture 18 Preview

All living things need matter to build and repair parts, and energy to move, organize, and build.

• Producers get energy from sunlight and matter (nutrients) from the air and the ground.
  • gases get in and out through leaves
  • water and ions get in through roots with many, hairlike projections
• Consumers get energy and matter from other organisms

How cells in consumers get food  [a pizza will not go through a plasma membrane]

• Consumers of dead things are decomposers (usually bacteria, protists, and fungi).  Fungal decomposers release digestive enzymes to break food polymers to monomers; then absorb monomers through their hyphae, which are many, hairlike projections
• Consumers of live things take pieces of food in, mechanically break down pieces to smaller pieces, chemically digest polymers to monomers, absorb monomers for transport to cells, collect and remove undigested wastes

Consumers of live things have digestive systems that are basically one tube with specialized regions.  What is the specialized function of each region?

In what part or organ would you find

• structures for mechanical breakdown?
• enzymes for chemical breakdown?
• many, hairlike projections for absorbing nutrients?

Modifications of the basic design occur in vertebrates and invertebrates.

Parts of the digestive system are specialized in herbivores and carnivores, because plant matter has more undigestible fibers and smaller amounts of usable nutrients than meat.

Which is the herbivore and which is the carnivore?  What specializations are present?

Which digestive system would take more energy to build and maintain?

Which feeding style would take more energy:  being an herbivore or being a carnivore?

Most living things need oxygen to help transfer the energy from glucose to energy in ATP.  Most living things also need to get rid of carbon dioxide, a waste product from respiration.  Consumers must exchange gases with their environment.

Gas is exchanged only by diffusion, so rapid movement

• requires different concentrations inside and out
• requires lots of surface area for exchange
• is limited to a short distance

Small organisms have larger surfaces relative to their volumes and not too many layers of cells; they can exchange gases through their body surface.  Large organisms have less surface area relative to volume and many layers of cells; they need special gas exchange organs.

There is a higher concentration of oxygen in air (21%) than in water (0.5-1%), but land organisms often lose water when they exchange gases.  Where do land organisms have gas exchange membranes and where do water organisms have gas exchange membranes?

How do the alveoli (air sacs) in lungs and gill filaments in gills aid gas exchange?

Gas exchange can also be aided by having air or water pushed past the gas exchange surface and having oxygen carriers in a fluid carrying the oxygen.

What kind of gas exchange system would take the most energy to build and maintain?

Would the energy expense be worth the benefits to your organism?