Scientific Method & Graphing
True or False: If an experiment does not validate your hypothesis, you stop thinking about the original question.
False, you revise the hypothesis and figure out a way to experimentally test the revised hypothesis.
The prefix milli means what?
1/1000
Density and hardness are examples of (physical or chemical?) properties?
Physical
Which phases of matter expand to fill their container?
Only gas phase
True or false: there are atoms of elements in the human body that do not exist in the rest of nature
False.
Human bodies are composed mostly of 5 or 6 basic elements, all of which are found in other living things and in various nonliving items.
These elements are in fact "recycled" to the ecosystem upon death.
A student varies the amount of salt in various solutions of salt water and tests the degree to which each solution bends light. What is an appropriate control group?
Pure water with no salt
CH4 + 2O2 -> CO2 + 2H2O is an example of a (physical or chemical?) change?
chemical, the chemical identity of the reactants is different than that of the products.
A phase change, such as going from a liquid to a gas, is an example of a (physical or chemical?) change?
Physical
Because the chemical identity of the substance has not changed, i.e. the molecular formula for the substance has not changed.
Homeostasis refers to what?
The need to keep a number of variables within a particular range for life.
examples provided were temperature, pH, concentrations of various chemicals
When a student studies the impact of fertilizer amount on the height of a particular species of plant, what is the dependent variable?
The height of the plant
Convert 12cm into mm
12cm = 120mm
centi = 1/100
milli = 1/1000
There are 10/1000 in 1/100. There are 10mm in 1cm
What is a homogenous mixture?
A mixture of two different substances with a single uniform composition (i.e. you cannot visibly tell that it is a mixture)
Salt water is an example
If you add heat to liquid water that is cold, what will first occur?
The liquid water will get warmer (and hence be warmer liquid water)
True or False: The human population is undergoing evolution currently
True. Note that this does not mean we are transforming into some higher level of animal than a human, it simply means that traits (for example average height) are changing with time in the population.
A student varies the amount of time per day that a plants from the same species are exposed to sunlight. For example the first plant gets no sunlight, the second plant gets on hour of sunlight per day, etc. What are some constants that the experimenter might maintain?
The experimenter is keeping constant:
*the species of plant
* the source of light
* the type of container
* the location in which sunlight is experienced
etc.
Use dimensional analysis to convert 350 miles per hour into meters per second. 1 mile = 1.61 km
(350 miles / 1 hour) * (1.61 km/ mile) * (1000 meters/km) * (1 hour / 60 minutes) * (1 min / 60 seconds) = 156.5 meters / second
Provide two different categories of "pure substances"
elements and compounds, with compounds being molecules that consist of more than one atom.
Example: Zn is an element, while O2 and H2O are compounds
If you add heat to ice that is at a temperature of zero degrees Celsius, what happens?
The ice melts, because zero degrees Celsius is the melting point of H2O.
True or False: A rock being forced down a stream by flowing water is an example of response to stimuli
False.
The rock was acted upon, rather than the rock reacting. Only living things react to stimuli.
A student wants to create an even axis scale for the independent variable of a data set. The largest independent variable value is 3185cm, and the smallest value is 35cm. The graph paper provided to the student has 35 boxes available on the x axis. How much can the student make each box worth in order to have an EVEN and APPROPRIATE axis scale? What label should the student place on the x-axis
The label is length (cm)
3185 - 35 = 3150 (range)
3150/35 = 90
The actual amount per box can be HIGHER than this estimate (90cm per box) but not lower. A suitable amount would be 100cm per box.
Use dimensional analysis to calculate how many minutes are in a 30-day month?
60 minutes per hour * 24 hours per day * 30 days = 43,200 minutes
Define Condensation
When a gas condenses into a liquid.
The most common experience with this is when water vapor from the air condenses on the container of a cold beverage.
sublimation is what?
The process of a solid going straight to a gas, without spending time in a liquid phase.
Growth in multicellular organisms is mostly a result of what basic process?
Cell division