bsc 1005 lab - midterm review

the energy levels in which electrons orbit around the ____________ are also called _____________

nucleus; electron shells

sometimes, atoms share more than two electrons to complete their ____________ and will share two pairs to create a ____________ bond of three pairs to create a ____________ bond

octets; double; triple

which statement regarding the scientific method is false?

original hypothesis are formed after an experiment

atoms with more than one shell are most stable when the ___________ shell contains 8 electrons

outer

the ____________ value of a solution becomes _____________ when more hydrogen ions are released by an acid

pH; lower

the ___________ displays all of the elements, and therefore the atoms, based on their chemical and physical properties

periodic table

when graphing your data, it is important that you

place the independent variable on the x-axis

starch is a(n)

polysaccharide

which category of macromolecules is associated with catalytic activity?

proteins

the positive control for the iodine test was the

starch solution

polysaccharides are polymers composed of

sugars

which of the following are functions of proteins?

- catalytic activity - structural support

when atoms combine to form compounds, they can ___________ electrons

- give up - accept - share

basic substances:

- human blood - antacids - milk of magnesia - ammonia - sodium hydroxide

acidic substances:

- hydrochloric acid - stomach acid - lemon juice - soda - tomatoes - black coffee

which classes of macromolecules have a significant role in energy storage? (select all that apply)

- lipids -carbohydrates

which classes of macromolecules have a significant role in energy storage?

- lipids - carbohydrates

before you begin a scientific experiment, you should:

- state a hypothesis - decide on a strategy

which of the following are functions of lipids?

- storage of energy - membrane support

which of the following are functions of carbohydrates?

- storage of energy - structural support

neutral substances:

- tears - pure water

when determining the scope of an experiment, you need to consider (check all that apply)

- the outcome you will investigate - the factor that will vary

science is about coming up with a hypothesis and

testing it

positive biuret test

violet

use the portion of the periodic table to complete the following statements. not all choices will be used.

- the atomic symbol for the element in group 2, period 4 is Ca - it has 20 protons, which have a positive charge and 20 neutrons, which have no charge. both of these subatomic particles are found within the nucleus - when this element has no overall charge, it has 20 electrons, which carry a negative charge and found outside the nucleus - the atomic number of Si is 14, while the atomic mass is 28.09 - when CI has no overall charge, it has 17 electrons

match the action to the appropriate phase of the scientific method

1. analysis: draw graphs, evaluate the hypothesis 2. experiment: carry out the strategy, collect measurements 3. report: document results 4. hypothesis: formulate a hypothesis and create a strategy

match each test with the substance it is intended to detect

1. brown paper test - lipids 2. biuret test - protein 3. iodine - starch 4. benedict's - simple sugars

place the 4 phases of the scientific method in order:

1. hypothesis 2. experiment 3. analysis 4. report

an atom of helium has one electron shell and it is full when it contains ____________ electrons

2

when atoms have more than one electron shell, the valence shell is full when it contains ___________ electrons

8

_____________ is a strong acid because it almost fully dissociates into hydrogen ions and _____________ ions in water

HCl; chloride

_____________ is a strong base because it almost fully dissociates into hydroxide ions and ____________ ions in water

NaOH; sodium

a polar covalent bond can best be described as

a bond where electrons are unequally shared, resulting in more electrons orbiting certain atoms than others

carbohydrates like glycogen and cellulose are polymers. what is a polymer?

a chain of similar building blocks called subunits, or monomers

imagine that you wish to compare two different diets that will be fed to tadpoles raised in a lab. one diet is a meat-based fish food, and the other is the traditional diet of boiled lettuce. you want to see if the meat-based diet will be associated with an increase in the average weight of the tadpoles. in your experiment you keep all other factors, such as tadpole density per pan, temperature, pH, and the amount of food the same. the only difference between the control and experimental groups is the type food the tadpoles receive. what is the dependent variable for the tadpole diet experiment?

size of tadpoles

some students consume large amounts of coffee and so-called energy drinks to help them stay alert when studying. you notice that many who engage in this practice seem to do poorly on exams. suppose you want to investigate the relationship between caffeine consumption and exam performance. which of the following statements would be an appropriate hypothesis?

students who consume large amounts of caffeine while studying will have lower exam scores than those who consume less caffeine

imagine that you wish to compare two different diets that will be fed to tadpoles raised in a lab. one diet is a meat-based fish food, and the other is the traditional diet of boiled lettuce. you want to see if the meat-based diet will be associated with an increase in the average weight of the tadpoles. in your experiment you keep all other factors, such as tadpole density per pan, temperature, pH, and the amount of food the same. the only difference between the control and experimental groups is the type food the tadpoles receive. which is a good hypothesis for this tadpole experiment?

tadpoles will be larger if fed a meat-based diet

in order to come to reliable conclusions about pillbug preferences, you need to use

the scientific method

if you wanted to test whether or not a particular pain reliever was effective in the general population, you would need to design an experiment with an experimental group and a control group. what should be the only difference between these two groups?

treatment: the experimental group should get the pain reliever, and the control group should get a placebo

a drop of liquids that does not evaporate from brown paper after a 20-minute period at room temperature contains lipids

true

you should use the graph generated from your data to see if your hypothesis is supported

true

the electrons that are in the outermost electron shell, also known as the _____________, have ____________ energy than those in the inner electron shells

valence shells; more

the weak attractive forces that hold water molecules together are called

hydrogen bonds

these chemicals work by taking up excess ____________ when acids are added to the body and ____________ when bases are added to the body

hydrogen ions; hydroxide ions

substances that release ______________ ions or take up hydrogen ions when dissociated in water are called ______________

hydroxide; bases

a/an __________ should be based on background knowledge and observations

hypothesis

how many phases make up the scientific method?

4

according to the lab, formulating a true hypothesis is far less important than:

coming up with a good strategy to test the hypothesis

a(n) ___________ results when two atoms share ____________ in order to have a completed outer shell

covalent bond; electrons

which of the following would form ionic bonds?

- Na and F - Na and C

which reagent is used to detect the presence of protein?

biuret

the negative control used in the tests for protein, lipids, sugars, and starch was

distilled water

a hypothesis must be:

testable

magnesium wants to have 8 electrons, so it __________ 2 electrons to another atom, so its valence shell is full and a ___________ is created between the two atoms

donates; bond

chlorine will then ___________ the electron leaving both atoms with an outer shell of 8 electrons

accept

diseases such as diabetes and congestive heart failure may bring on a condition called ____________, in which the body is unable to buffer the excessive production of hydrogen ions

acidosis

substances that release hydrogen ions when dissociated in water are called ____________

acids

the biuret test would indicate a positive result for proteins in which of the following solutions?

albumin solution

negative iodine test

amber

proteins are polymers composed of

amino acids

which statement correctly describes ionic bonds?

an ionic bond is the electrostatic force that holds ions together when they form bonds

which pair of statements below is correct?

an octet is formed via iconic bonding when one or more valence electrons are transferred from one atom to another. an octet is formed via covalent bonding when valence electron are shared between atom

in the analysis phase, you will need to

analyze your data and place it on a graph

the ___________ is written below the atomic the atomic symbol and reflects the number of protons and neutrons in an atom

atomic mass

the ___________ is written above the atomic symbol and reflects the number of protons the atoms has and makes it unique

atomic number

an ionic bond is a type of bond that joins ___________

atoms

the atomic theory states that elements consist of tiny particles called __________

atoms

for example, two hydrogen ___________ will share their electrons and these electrons will spend part of their time in the ___________ shell of each atom

atoms; outer

which of the following tests is used to detect the presence of lipids?

brown paper test

chemicals or a combination of chemicals that keeps pH levels within normal limits are called ____________

buffers

in the pillbug experiment, once you have recorded the data in the notebook, you must

calculate average values, then plot the values on a graph

in the human body, pH needs to be kept within a narrow range in order to maintain _____________

homeostasis

in an experiment, the variable that you will measure is the ________ variable

dependent

when utilizing the scientific method, there are two types of variables. they are:

dependent & independent

imagine that you wish to compare two different diets that will be fed to tadpoles raised in a lab. one diet is a meat-based fish food, and the other is the traditional diet of boiled lettuce. you want to see if the meat-based diet will be associated with an increase in the average weight of the tadpoles. in your experiment you keep all other factors, such as tadpole density per pan, temperature, pH, and the amount of food the same. the only difference between the control and experimental groups is the type food the tadpoles receive. what is the independent variable for the tadpole diet experiment?

diet

a negative control is a sample that you know will give you a negative result. you are testing for the presence of proteins, simple sugars, starch, and lipids in various foods. what would be the best negative control for this experiment?

distilled water, because it does not contain any of the molecules you are testing for

during an ionic reaction, atoms give up or receive ___________ to ensure a stable outer shell

electrons

nonliving and living matter are composed of _________ that cannot be broken down further

elements

in the _______ phase, you will carry out the strategy you developed for testing the hypothesis

experiment

compared to the polar covalent bonds that hold the oxygen and hydrogen atoms together within a molecules of water, the hydrogen bonds that hold multiple water molecules together are much stronger

false

electrons possess a negative charge. so, within a molecule of water, if more electrons are orbiting the oxygen atom than the two hydrogen atoms, the oxygen atom will have a slightly more positive charge than the hydrogen atoms

false

if the hypothesis in a scientific experiment is not supported, the experiment is considered a complete failure and must be repeated until a satisfactory outcome is reached

false

in experiments, it is common to include a sample of a substance known to react with the reagent. this allows the experimenter to verify the test (reagent) is working correctly. this sample is known as the negative control

false

making sure that you come up with a hypothesis that makes a true statement is by far the most important aspect of the scientific method

false

scientists are the only individuals who use the scientific method

false

sodium has 1 valence electron, which it shares with fluorine to form a covalent bond

false

when formulating a hypothesis, it is important to determine the scope, then pick four or five factors to focus on

false

you do not need to pause to record your data as you perform your experiment. you can go back and estimate the values when the experiment is complete.

false

in the formation of the compound NaCl, sodium will ___________ one of its outer shell electrons

give up

the more hydroxide ions released or the more hydrogen ions taken up by the bases, the _____________ the pH value of the solution

higher

according to your lab, the variable that you manipulate during the experiment (the one that "varies"), is the ________ variable

independent

which reagent is used to detect the presence of starch?

iodine

atoms of the same element with varying numbers of neutrons, some of which produce radiation that may be useful medically, are called ___________

isotopes

which group of molecules are insoluble in water?

lipids

which of the following is completely insoluble in water?

lipids

while testing for an emulsifier, one of the test tubes showed a layer of oil sitting on top of the water. what property of lipids causes this to occur?

lipids are nonpolar and so do not mix with polar water molecules

a single atom may form bonds with more than one other atom, like ____________, which is a carbon atom bound to four hydrogen atoms

methane

when water molecules are combined, which of the following is the most likely orientation of oxygen and hydrogen atoms of different molecules?

oxygen atoms of one molecule attract hydrogen atoms of other molecules, so that each oxygen atom is opposite the two hydrogen atoms from nearby molecules

when graphing your data, it is important to

place the dependent variable on the y-axis

which of the following is a great source of carbohydrates?

potato