BIO chapter 20 Viruses, Prokaryotes, & Protista

These flashcards cover key concepts and terminology related to the classification, characteristics, and roles of microbes and protists in various biological processes.

What are the three domains into which all living things on Earth can be classified?

Bacteria, Archaea, and Eukarya.

Which domains of life are all single-celled and microscopic?

Bacteria and Archaea.

What are the four kingdoms within the Domain Eukarya?

Plants, animals, fungi, and protists.

What does the term 'microbes' refer to?

Living things so small they cannot be seen with the naked eye.

What essential atmospheric gas do microbes produce more than half of?

Oxygen.

Which types of microbes fix atmospheric nitrogen into a usable form for plants?

Bacteria and archaea.

Who are the most important decomposers in the natural world?

Bacteria and fungi.

The total weight or _ of all microbes on Earth exceeds that of all larger life-forms.

biomass.

What are noncellular replicating entities that must invade living cells to replicate?

Viruses.

Why are viruses not classified as living things by most scientists?

They can carry out very few of life’s basic processes on their own.

What are the two structures common to all viruses?

Genetic material and a protein coat called a capsid.

What is the fatty membrane that surrounds the capsid in many viruses called?

An envelope.

HIV primarily invades and destroys which type of immune system cells?

Helper T-cells.

What enzyme synthesizes DNA from the viral RNA in HIV?

Reverse transcriptase.

What is the function of integrase in the HIV life cycle?

It splices the viral DNA into the host cell's DNA.

What enzyme assists in producing materials for viral clones during HIV's life cycle?

Protease.

What is the first step in the life cycle of most viruses?

They get their genetic material inside a 'host' cell.

The H1N1 virus is a member of which virus class?

Influenza A viruses.

What term describes organisms whose genetic material is not within a nucleus?

Prokaryotes.

What are two defining features of bacteria?

They have a single organelle (the ribosome) and reproduce asexually through binary fission.

What is 'binary fission'?

A simple cell splitting process through which bacteria reproduce asexually.

What type of relationship exists where both humans and bacteria benefit?

Mutualism.

How do humans benefit from their relationship with bacteria in the digestive tract?

Gut bacteria help digestive systems function efficiently.

What term is used to describe disease-causing bacteria?

Pathogenic.

How do pathogenic bacteria damage the human body?

By releasing or leaving behind harmful substances called toxins.

What are antibiotics?

Substances produced by one microorganism that are toxic to another.

They work by targeting differences between bacteria cells and human cells so they can kill bacteria without harming human cells.

What was the first antibiotic developed in the 1940s?

Penicillin.

How do antibiotics target bacteria without harming human cells?

They exploit the differences between bacterial and human cells.

What is the primary cause of antibiotic-resistant bacteria?

The overuse of antibiotics in medicine and agriculture.

What does MRSA stand for?

Methicillin-resistant Staphylococcus aureus.

Archaea are similar to bacteria in that they are single-celled prokaryotes that reproduce through _?

simple cell splitting.

At what level are archaea unique compared to bacteria?

The chemical structure of their cells.

In large portions of the world's oceans, archaea make up what percentage of microbial life?

40 percent.

What are extremophiles?

Organisms that grow optimally in environments whose conditions would kill most other organisms.

What are thermophiles?

A class of extremophiles that live in extremely hot environments.

What are halophiles?

A class of extremophiles that live in extremely salty environments.

What class of extremophiles can do without oxygen or are poisoned by it?

Anaerobes.

What is a protist?

A eukaryotic organism that does not have all the defining features of a plant, an animal, or a fungus.

Why is the definition of a protist considered unsatisfactory evolutionary?

It refers to several different evolutionary lines, not a single grouping.

Where do most protists live?

In environments that are somewhat moist; including freshwater and marine environments, damp soil, and even snow.

What pathogenic protist causes malaria?

Plasmodium falciparum.

What intestinal parasite contaminates water?

Giardia.

What was the first life-form to evolve after bacteria or archaea?

Protists.

What form of reproduction did protists first practice?

Sexual reproduction.

What type of protists perform photosynthesis?

Algae.

What is colonial multicellularity?

A form of life where individual cells form stable associations but do not specialize.

What is true multicellularity?

A form of life where different cells specialize in various functions.

What are phytoplankton?

Small photosynthesizing organisms that float near the surface of water.

Why are phytoplankton important to life on Earth?

They produce most of Earth’s oxygen and create many aquatic food chains.

All phytoplankton belong to which groups?

Algae or bacteria.

What are heterotrophic protists?

Protists that get nutrients from consuming other organisms or organic matter.

What structures do some heterotrophic protists use to move?

Cilia and flagella.

How do amoebas move?

By using pseudopods or 'false feet'.

What process similar to amoebas do plasmodial and cellular slime molds use to move?

Cytoplasmic streaming.