Movement of an organism in response to a chemical stimulus is called chemotaxis.
Missing Word
chemotaxis
Chemotaxis is directed movement toward or away from a chemical, such as a bacterium swimming toward nutrients. It is an example of the response to stimuli shown by all living things.
Category: Properties of Life
Question 2
The maintenance of a stable body temperature, one form of homeostasis, is called thermoregulation.
Missing Word
thermoregulation
Thermoregulation keeps body temperature within a narrow range, for example by sweating or shivering in humans. It is a specific case of the broader process of homeostasis.
Category: Properties of Life
Question 3
The ability of organisms to make new individuals and pass their DNA on to offspring is called reproduction.
Missing Word
reproduction
Reproduction is a property of all life. Single-celled organisms may divide in two, while many multicellular organisms reproduce sexually, and in each case genetic information passes to the next generation.
Category: Properties of Life
Question 4
Organisms whose cells lack a nucleus and membrane-bound organelles are called prokaryotes.
Missing Word
prokaryotes
Prokaryotes are single-celled organisms in the domains Bacteria and Archaea. Their DNA is not enclosed in a nucleus, unlike the cells of eukaryotes.
Category: Classifying Life
Question 5
Organisms that thrive in harsh conditions such as boiling hot springs or extremely salty water are called extremophiles.
Missing Word
extremophiles
Extremophiles live in environments that would kill most other organisms. Many members of the domain Archaea are extremophiles.
Category: Classifying Life
Question 6
The domain that includes familiar single-celled microbes such as E. coli, whose cells have no nucleus, is Bacteria.
Missing Word
Bacteria
Bacteria is one of the two prokaryotic domains, alongside Archaea. E. coli, a common inhabitant of the human gut, is a well-known member.
Category: Classifying Life
Question 7
The Swedish scientist who in the 1700s developed the system of two-part scientific names was Linnaeus.
Missing Word
Linnaeus
Carolus Linnaeus introduced binomial naming, in which each species gets a genus name and a species name. He also organized living things into a nested hierarchy of categories.
Category: Classifying Life
Question 8
A biologist who studies the interactions of organisms with one another and with their environment is called an ecologist.
Missing Word
ecologist
An ecologist studies relationships among organisms and between organisms and their surroundings. Their work ranges from single populations to whole ecosystems.
Category: Branches of Biology
Question 9
The branch of biology that studies microscopic organisms is called microbiology.
Missing Word
microbiology
Microbiology is the study of microorganisms, life forms too small to see without a microscope. It includes work on their structure, function and roles in disease and the environment.
Category: Branches of Biology
Question 10
The study of how the parts of living organisms function, such as how the heart pumps blood, is called physiology.
Missing Word
physiology
Physiology examines the normal functions of living systems and their parts. A physiologist might study how organs, tissues or cells carry out their jobs.
Category: Branches of Biology
Question 11
The field that examines the moral questions raised by advances in biology, such as genetic engineering, is called bioethics.
Missing Word
bioethics
Bioethics weighs the right and wrong uses of biological knowledge and technology. As new tools like gene editing appear, the field addresses how they should and should not be used.
Category: Branches of Biology
Question 12
A testable, tentative explanation for an observation is called a hypothesis.
Missing Word
hypothesis
A hypothesis is a proposed explanation that leads to predictions that can be tested by experiment. If the results contradict it, the hypothesis is rejected or revised.
Category: Scientific Method
Question 13
In an experiment, any part or factor that can change or be changed is called a variable.
Missing Word
variable
A variable is any factor that can vary in an experiment. In a well-designed experiment, scientists change one factor on purpose and keep the others constant.
Category: Scientific Method
Question 14
Random changes in the DNA sequence, which provide the raw variation that natural selection acts upon, are called mutations.
Missing Word
mutations
Mutations are changes in an organism's DNA. They create new inherited variations, and natural selection can then make the helpful ones more common over generations.
Category: Properties of Life
Question 15
An unexpected, fortunate discovery made by accident, such as the finding of penicillin, is an example of serendipity.
Missing Word
serendipity
Serendipity is a lucky accidental discovery. Alexander Fleming noticed that a mold contaminating a bacterial culture killed the bacteria, which led to penicillin.
Category: Basic and Applied Science