Transcript
Concept Check 16.1
1. What do fossils found in stromatolites indicate about early life on Earth (3.5 billion
years ago)?
It indicates that early prokaryotes lived in colonies similar to today.
2. What did Stanley Miller's experiment contribute to hypotheses of how life began?
That small organic molecules could have formed as chemical processes of early earth.
3. Describe two environments where life might have first appeared.
Shallow water or moist clay.
Concept Check 16.2
1. In what major ways are archaea different from bacteria?
They are different in cell structure and chemical make up.
2. What are the three major cell shapes of bacteria?
The three major cell shapes of bacteria are cocci (circle), cacilli (rod), and spirochetes (spiral).
3. Describe three ways bacteria can recombine their genetic material.
Bacteria can recombine their genetic material through transformation, conjugation, and transduction.
4. Name the four major modes of prokaryotic nutrition. For each, identify the energy
source and carbon source.
Four major modes of prokaryotic nutrition are photoautotroph (Sunlight; CO2), chemoautotroph (Inorganic chemicals; CO2), photoheterotroph (Sunlight; Organic compounds), and chemoheterotroph (Organic compounds; Organic compounds).
5. How did cyanobacteria change Earth's early atmosphere?
Cyanobacteria generated oxygen as a byproduct of photosynthesis, which bubbled to the surface of lakes and oceans, then entered the atmosphere, forming the ozone layer.
Concept Check 16.3
1. How do prokaryotes recycle carbon and make nitrogen available to plants?
Prokaryotes break down organic wastes and release carbon dioxide, convert nitrogen in the air to nitrogen compounds that plants can use.
2. How are prokaryotes used to treat sewage?
Prokaryotes are used to treat sewage by decomposing organic matter in sludge that settles out from raw sewage.
3. Give an example, other than sewage treatment, of how prokaryotes can be used by
humans.
Prokaryotes can be used by humans for cleaning up oil spills, cleaning up mining sites, making vitamins and antibiotics, making copies of genes and proteins.
Concept Check 16.4
1. Describe two kinds of bacterial poisons.
Bacterial-cell protein secretions, bacterial cell-wall components.
2. List and describe three ways in which humans can fight bacterial disease.
Better hygiene can help prevent pathogen infection, careful food preparation can minimize risk of food borne illness, antibiotics can fight bacterial diseases in the body.
3. Describe one concern about the overuse of antibiotics.
Overuse of antibiotics may result in the spread of resistance in bacterial populations.
Concept Check 16.5
1. Describe the lytic and lysogenic life cycles of viruses.
The lytic cycle is a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses. The virus injects DNA into host, phage DNA remains separate from host DNA, host makes copies of phage DNA and proteins, new viruses are released. The lysogenic cycle is a viral reproductive cycle in which the viral DNA is added to the host cell’s DNA and is copied along with the host cell’s DNA. The virus injects DNA into host, phage DNA inserts itself into host DNA, phage DNA is copied but no new viruses are reproduced.
2. How is a viral infection different from a bacterial infection?
Viruses invade cells and uses its machinery in making new viruses. Most pathogenic bacteria produce toxins, or components of their cell wall are toxic to cells. Some invade and destroy cells.
3. During what point of the HIV life cycle does an infected person develop AIDS?
When HIV begins to reproduce and destroy the cells of the immune system
4. Describe techniques used to fight viruses in humans.
Better hygiene, vaccines, drugs that interfere with viral reproduction
