NAS 2 CHALLENGE TEST/89 QUESTIONS
AND ANSWERS 2024
purpose of the scientific method - -an organized way to solve a problem or
answer a question
-independent variable - -a variable that the researcher controls and is not
affected by other variables
ex: amount of water a plant receives
-What are the steps of the scientific method? - -1. question
2. Hypothesis
3. experiment
4. observation
5. analyze
6. conclusion
-dependent variable - -a variable that depends on other factors or variables
ex: how much the plant grows
-control group - -group that does not receive any treatment and is used to
compare or measure the other subjects
-experimental group - -group that receives treatment in an experiment
-what are the six levels of organization - -chemical, cellular, tissue, organ,
organ system, organism
-identify the requirements of life - -response to stimuli, reproduction,
metabolism, cellular organization, regulation, growth and development,
homeostasis
-identify survival needs - -oxygen, nutrients, water, body temperature,
atmospheric pressure
-define homeostasis - -body maintains a stable internal environment while
adjusting to external conditions
-Receptor - -a sensor that monitors the environment and responds to
changes (called stimuli) by sending the information to the control center
-control center - -determines the set point (level or range a variable is to be
maintained at), analyzes the information it receives, and determines the
appropriate response.
, -effector - -provides the means for the control center's response to the
stimulus
-negative feedback mechanisms - -a feedback mechanism that slows or
stops a process. Reduces the effect of the stimulus which decreases
productivity
ex: the control of blood sugar
-positive feedback mechanisms - -a feedback mechanism that results in the
enhancement of the original stimulus so the activity is accelerated
ex: childbirth (if childbirth takes too long the life of the mother and baby are
at risk)
-protons - -positive, in the nucleus
-electron - -negatively charged particle in the outer shell
-neutron - -neutral charge, in the nucleus
-number of protons is the same as? - -the number of electrons
-what is the atomic number equal to - -number of protons (atomic number
is top left above atomic symbol)
-atomic mass - -the same as the protons and neutrons added together (at
the bottom below atomic symbol)
-characteristics of ionic bonds - -between metal and nonmetal, high melting
and boiling points, generally solid at room temp, hard/brittle, conducts
electricity, dissolves in water, gives up one or more electrons to another
atom
-characteristics of covalent bonds - -between nonmetal only(metalloids),
atoms share electrons, lower melting and boiling point, usually liquid and gas
at room temp, soft, not a conductor of electricity, insoluble (don't dissolve)
-characteristics of hydrogen bonds - -more of an attraction than a bond,
generally weak bond, always include hydrogen that is already part of a polar
molecule
ex: water
-non-polar covalent bond - -electrons are shared equally between two
atoms
-polar covalent bond - -unequal sharing of electrons between two atoms