LT 1: characteristics of life
The smallest thing that can live on its own.
A cell.
A necessary statement which defines what will be tested and how, typically written in an "If...then..." format
Hypothesis
Between a peer-reviewed journal or an anonymous blog, this is the more credible option out of the two, and why.
The peer-reviewed journal, because the blog isn't written by qualified experts on the subject.
Not necessary, extra explanation:
Peer-reviewed publications are experiments which were conducted by experts, and then looked over by other scientists (this is the "peer-review" part) to ensure everything they said is legitimate, before it's even able to be published.
This is the term that describes something which dissolves other things
Solvent
You climb out of a swimming pool on a windy day and feel cold, even though it's warm outside. Which property of water explains this?
Evaporative cooling
The term for all the chemical reactions that happen inside an organism, and is why living things must obtain nutrients (to fuel these reactions)
Metabolism
This is the reason why research is important before carrying out the scientific inquiry.
The scientist can find out what's already known about the topic, what happened in the past, and generally just have guidelines in place instead of starting completely from scratch
An example of this kind of error during a scientific experiment is when the researcher uses a scale that always reads too high.
Systematic error
The term that describes how water molecules sticks to other water molecules (like a stick bug being able to walk on water)
Cohesion
A student says, "Energy drinks improve memory. I read it on the energy drink company's website." What's the problem with this source?
It's biased and not credible. The company profits from the claim, and the website isn't independent or peer reviewed.
Keeping a stable internal environment even when outside conditions change.
Homeostasis
This is the variable the scientist changes on purpose to learn its effect.
The independent variable
This type of error is unpredictable error between trials, like a storm causing a black-out where electricity gets cut during the experiment which needs it
Random error
This is what water is called since, as a molecule, it has a negatively-charged end and a positively-charged end.
Polar molecule
You dip the corner of a paper towel in juice, and the juice creeps up the towel. What is this called, and which two properties cause it?
Capillary action, caused by cohesion and adhesion
Name three characteristics that ALL living things share that we haven't gone over yet.
Any three of the following: reproduce, grow and develop, respond to their environment, evolve over time as a group
The group that does NOT receive the change being tested and is used for comparison.
This is why scientists say data "supports" a hypothesis instead of "proves" it.
New evidence could always contradict it. One experiment can't account for every possibility, so science stays open to revision.
This is why ice floats on liquid water.
Ice is less dense. When water freezes, hydrogen bonds lock the molecules into a spread-out structure.
A student tests whether background music affects how fast mice solve a maze. What are the independent and dependent variables?
Independent variable: the music (whether it plays, or what type). Dependent variable: the time it takes to solve the maze.
A virus has genetic material, but it can only reproduce inside a host cell. Is it alive? Use the characteristics of life to explain.
Usually it is NOT considered alive, it isn't made of structured/coordinated cells, and it can't reproduce or carry out metabolism on its own. (Other well-made arguments might be accepted as well)
In an experiment where someone wants to see if melatonin makes lab rats sleepy, what would be examples of control variables for this experiment?
Same amount of food, water, exercise the rats are getting, same species of rat, being on no other medications, etc.
A student finds a website that says, "Studies show chocolate cures colds!" There is no author listed, no studies are linked, and the page was last updated in 2009. Give TWO reasons this source isn't credible, and say how the student could check the claim.
Any two of these reasons: no author or credentials, no evidence or citations, outdated. To check the claim, the person could look for peer-reviewed studies or a trusted source like a university, government health agency or scientific journal.
Imagine water molecules were NOT polar and couldn't form hydrogen bonds. Name TWO ways life on Earth would be different.
Any two of the following, with reasoning:
A student measures how fast ice cubes melt. Her thermometer reads 3°C too high every time, and she puts some cubes in sunlight and others in shade. Name the type of error the thermometer causes, AND the variable she failed to keep constant.
Systematic error, and sunlight (light or heat exposure)