Ch 08 key concept HW

Endosymbiosis is the internalization of one species by a host species. According to the endosymbiotic hypothesis, internalized prokaryotes eventually evolved into eukaryotic organelles. Drag the images to the targets of Group 1 in the order of the endosymbiotic hypothesis. Then match each description with the appropriate step.

1) Ancestral cell with nucleus andendomembrane system. 2) Oxygen metabolizing bacterium begins to be engulfed by ancestral cell. 3) Oxygen metabolizing bacterium is fully engulfed in the cell. 4) Photosynthetic prokaryote begins to be engulfed by ancestral cell. 5) Photosynthetic prokaryote is fully engulfed, resulting in a eukaryotic cell with organelles.(Ancestral prokaryotic cells evolved into the first eukaryotic cells through an inward folding of the plasma membrane and the engulfment and incorporation of other free-living prokaryotic cells. Those engulfed cells functioned as organelles that metabolize oxygen and photosynthesize.)

Can you place each word in the appropriate sentence? Part A Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.

1. The process of transduction involves the transfer of DNA from one bacterium to another by a virus. 2. The process of conjugation involves the building of a physical bridge between two bacteria. DNA then moves across this bridge from a donor cell to a recipient cell. 3. A plasmid is a small circular molecule of DNA that reproduces independently of the larger bacterial chromosome. 4. Most bacteria (and many other single-celled organisms) reproduce via binary fission, the process of dividing a cell in half, yielding two genetically identical offspring cells. 5. The process of transformation occurs when a bacterium internalized bits of DNA from its environment.

Can you match each term that relates to viruses with its description? Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

1. The protein coat that surrounds the nucleic acid of a virus is called a capsid. 2. Although generally not considered to be alive, a virus is studied alongside other microbes such as bacteria. 3. The lytic cycle is a viral life cycle that results in bursting of the host cell. 4. A prophage is a viral genome that has inserted itself into the genome of its host. 5. The lysogenic cycle is a viral life cycle in which the virus inserts its genome into the genome of its host, where it may remain dormant for long periods. 6. A bacteriophage is a virus that specifically infects bacteria.

How long ago did the first humans appear on earth?

2.5 million years ago

Which of the following pathogens causes mad cow disease?

A prion

Patients with advanced AIDS often die from infections that do little harm to healthy people. Why?

HIV infects and destroys the helper T cells of the immune system.

Can you sort the types of bacteria based on whether they are helpful or harmful? Part A Sort each type of bacteria according to whether it is helpful or harmful. Sort each item to the appropriate bin.

Helpful: decomposers nitrogen fixers probiotics Harmful: pathogens Salmonella MRSA

How does a bacterial cell obtain new DNA during the process of transformation?

Naked DNA from the surrounding environment is taken up by a bacterium.

Which one of the following soil-borne organisms can convert atmospheric nitrogen gas into ammonium and other nitrogen compounds that can be taken up and used by plants?

Nitrogen-fixing bacteria

Can you place these events from the evolutionary history of life on a time line? Part A Drag each event in the evolutionary history of life on Earth to its proper location on the time line.

Origin of Earth 4.6 First life 3.5 Eukaryotes 2.1 Multicellular life 1.2 First animals .6 Life moves on Land .5 Humans .02

Which of the following gases was the least abundant in the earth's early atmosphere?

Oxygen (O2)

The introduction of smallpox to the Americas by Europeans in the colonial era devastated populations of Native Americans. However, now very few people are vaccinated against the smallpox virus. Why?

Smallpox virus has been eliminated from the earth by vaccination of most of the people alive today.

Which eukaryotic structures are thought to have been the result of extensive inward folding of the plasma membrane of an ancestral prokaryotic cell?

The endoplasmic reticulum

What do the following groups of organisms have in common: methanogens (methane-producing organisms), halophiles (salt-loving organisms), and thermophiles (heat-loving organisms)?

They are all archaea.

Can you identify the functions of each part of the human immunodeficiency virus (HIV)? Part A Drag the labels to the appropriate locations on this diagram. Not all labels will be used.

a. helps HIV merge with a target cell's plasma membrane b. recognizes proteins on the outside of target cells c. produces a DNA copy of the HIV RNA genome d. RNA goes that direct production of more viruses e. surrounds and protects the HIV genome

Protists are ___________.

all eukaryotic

Bacteria with rod-shaped cells connected end-to-end are called _________.

bacilli

Binary fission produces __________.

two genetically identical bacterial cells