Chap16ccandans

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Concept ChecksChapter 16: Prokaryotes and Viruses

Concept Check 16.1

1. What do fossils found in stromatolites indicate about early life on Earth (3.5 billion years ago)? 2. What did Stanley Miller's experiment contribute to hypotheses of how life began? 3. Describe two environments where life might have first appeared.

Concept Check 16.2

1. In what major ways are archaea different from bacteria? 2. What are the three major cell shapes of bacteria? 3. Describe three ways bacteria can recombine their genetic material. 4. Name the four major modes of prokaryotic nutrition. For each, identify the energy source and carbon source. 5. How did cyanobacteria change Earth's early atmosphere?

Concept Check 16.3

1. How do prokaryotes recycle carbon and make nitrogen available to plants? 2. How are prokaryotes used to treat sewage? 3. Give an example, other than sewage treatment, of how prokaryotes can be used by humans.

Concept Check 16.4 1. Describe two kinds of bacterial poisons. 2. List and describe three ways in which humans can fight bacterial disease. 3. Describe one concern about the overuse of antibiotics.

Concept Check 16.5 1. Describe the lytic and lysogenic life cycles of viruses. 2. How is a viral infection different from a bacterial infection? 3. During what point of the HIV life cycle does an infected person develop AIDS? 4. Describe techniques used to fight viruses in humans. ANSWERS

Chapter 16: Prokaryotes and Viruses

Concept Check 16.1

1. What do fossils found in stromatolites indicate about early life on Earth (3.5 billion years ago)?

Fossils indicate that photosynthetic prokaryotes existed at that time.

2. What did Stanley Miller's experiment contribute to hypotheses of how life began?

Small organic molecules could be produced in environments similar to early Earth.

3. Describe two environments where life might have first appeared.

Shallow water, moist sediment like clay, deep-sea hydrothermal vents

Concept Check 16.2

1. In what major ways are archaea different from bacteria?

Differences in nucleic acid sequence, introns absent in bacteria, bacteria cell walls contain peptidoglycan

2. What are the three major cell shapes of bacteria?

Round, rod-shaped, and spiral

3. Describe three ways bacteria can recombine their genetic material.

Transformation- pieces of DNA in the environment are transported into the cell Conjugation- two bacterial cells join temporarily and transfer genetic material Transduction- genetic material is carried from one bacterium to another by viruses 4. Name the four major modes of prokaryotic nutrition. For each, identify the energy source and carbon source.

Photoautotroph- light energy, carbon dioxide Photoheterotroph- light energy, organic compounds Chemoautotroph- inorganic chemicals, carbon dioxide Chemoheterotroph- organic compounds, organic compunds

5. How did cyanobacteria change Earth's early atmosphere?

Produced oxygen asa byproduct of photosyntthesis

Concept Check 16.3

1. How do prokaryotes recycle carbon and make nitrogen available to plants?

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?

Decompose 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.

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.

Lytic: virus injects DNA into host, phage DNA remains separate from host DNA, host makes copies of phage DNA and proteins, new viruses are released. Lysogenic: 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