Chapter 8 Bio
Terms in this set (48)
The main hypothesis about the origin of the first living organisms is called ________.
What does the term biogenesis mean?
Formation of life from nonliving materials
Many of the organic molecules associated with life can be created spontaneously under certain conditions. What do these conditions resemble?
What are the main steps of biogenesis, in the correct order?
Monomers, Polymers, self-replicating molecules, first cells
What do scientists believe was the original genetic material able to copy itself without assistance?
By what means do prokaryotes typically divide?
Which protective structure forms to protect certain bacteria during periods of harsh conditions?
If you looked at unknown cells under a microscope, what could lead you to correctly conclude that they are prokaryotic cells?
They lack a nucleus.
Some bacteria have a spherical shape, called ________.
How many domains contain prokaryotic organisms?
Which organisms contain the smallest, least complex cell types?
Halophiles are a type of ________.
Where do you expect to find thermophiles?
In hot environments
Which organisms are called extremophiles and flourish mostly in extreme conditions?
Where would you expect to find methanogens?
In the digestive tract of cows
What statement is true regarding bacteria?
Some bacteria are pathogens and harmful to humans, whereas lots of bacteria are helpful to humans.
Nitrogen-fixing bacteria convert atmospheric nitrogen (N2 gas) into ammonium (NH4). Why is this conversion important for life on Earth?
Ammonium is a very important plant nutrient.
The practice of using bacteria to remove pollutants from the environment is called ________.
Food poisoning is often caused by a bacterium called ________.
What are some ways in which bacteria help the environment?
1) They remove pollutants from the environment.
2) They break down dead organisms in the soil and recycle nutrients.
3) They are used to water in sewage treatment facilities.
Which was first on the planet, prokaryotes or eukaryotes?
Pathogen is ________.
a name given only to bacteria that cause serious illnesses in humans
What is not a method bacteria use to generate new combinations of genes?
Bacteria reproduce asexually via binary fission. This process generates ________.
Genetically identical bacteria
Viruses that infect bacteria are called ________.
Which method of bacterial DNA transfer involves a physical connection between the two bacterial cells?
What are plasmids?
Small, circular DNA molecules that contain just a few genes and that can be passed on to other bacteria
How long did it take in the history of life on Earth to go from the first prokaryotic cells to the first eukaryotic cells?
Over a billion years
How does a transformed bacterial cell obtain new DNA?
the uptake of naked DNA from the surrounding environment
What is the leading scientific hypothesis explaining how the endomembrane system of eukaryotic cells originated?
From the inward folding of the plasma membrane
When did the first eukaryotic cell form?
2.1 billion years ago
How did mitochondria and chloroplasts arise in eukaryotic cells?
Via endosymbiosis, where mitochondria and chloroplasts were independent prokaryotic organisms that were engulfed by a larger cell
Based on the endosymbiosis theory that highlights where chloroplasts come from, how would you expect chloroplasts to divide when a plant cell divides?
Via binary fission
What might be the advantage to a cell if it assimilated a photosynthetic bacterium rather than digesting it?
It could now use sunlight to make its food.
Which protist group includes members with plantlike traits such as chloroplasts and multicellularity?
By what means do the amoebas move?
What are the steps toward multicellularity, in the correct order?
First a colony of protists forms, then some protists start to specialize in specific tasks, and finally some cells become gametes.
An organism is considered truly eukaryotic when ________.
its cells cannot survive on their own
Approximately when did the earth's crust solidify?
4 billion years ago
What began first?
Multicellular life in the ocean
Although most biologists do not consider viruses to be alive, viruses do share some characteristics with living things. Which of the following is the requirement for life that viruses lack?
The ability to reproduce on their own
Which viral life cycle would result in a quicker death for an infected cell?
How do viruses make copies of themselves?
By using the cellular machinery of the host cell they infected
Which specific cells are infected by the HIV virus?
Helper T cells
How does AZT fight AIDS?
It blocks the enzyme that converts viral RNA to DNA.
Where would you find the double-stranded HIV DNA in an infected cell?
Incorporated directly into the host cell's chromosome
HIV has an RNA genome that is converted to DNA when infecting a human immune cell. This type of virus is called a ________
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.