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Biology-12 > Unit 1: Quiz > Flashcards

Unit 1: Quiz Flashcards

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1
Q

What is random and normal variation?

A

Errors can be caused by changes in the material used, or by changes in the condition under which the experiment is carried out

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2
Q

How can random and normal variation be minimized?

A

By carefully selecting materials and careful control of variables, averaging the results of multiple trials also helps to minimize it

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3
Q

What is human error?

A

Human error occurs when tools, instruments or protocols are used or read incorrectly

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4
Q

Types of human error…

A

Human error is both systematic and random

Systematic: because the experimenter does not know how to use the apparatus properly (lab equipment)

Random: because the power of concentration of the experiment is fading (covid test analyze late at night)

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5
Q

Explain one mistake on lab…

A

Either systematic or random error

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6
Q

What is the act of measuring?

A

When a measurement is taken, this can affect the environment of the experiment

Ex. cold thermometer is put into a test tube with only a small volume of water, the water will be cooled by the presence of the thermometer, or when the behaviour of animals is being recorded, the presence of the experimenter may influence the animals behaviour

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7
Q

What are systematic errors and how can they be reduced?

A

Can be reduced if equipment is regularly checked or calibrated to ensure it is functioning correctly

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8
Q

What are replicates and samples?

A

Biological systems are complex and highly variable, multiple samples and replicate observations are therefore necessary in most investigations

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9
Q

How many replicates should you do to make an experiment accurate?

A

The lower limit is 5 measurements, or a sample size of five, the larger the sample the better

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10
Q

What is degrees of precisions and uncertainty in data

A

Students must choose an appropriate instrument for measuring such things as length, volume, pH, and light intensity

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11
Q

For a liquid which is more accurate….

A graduated cylinder, a pipette or a beaker?

A

Graduated cylinder or pipette is more suitable for measuring a liquid than a beaker

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12
Q

What is the degree of precision?

A

Is plus or minus half of the smallest division on the instrument (for each point of uncertainty)

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13
Q

Convert the following to percent uncertainties…

2.70+/- 0.05 cm

A

1.85%

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14
Q

Convert the following to percent uncertainties…

12.02 +/- 0.08 cm

A

0.67%

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15
Q

Covert the following to absolute uncertainties…

3.5 cm +/- 10%

A

0.35

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16
Q

Covert the following to absolute uncertainties…

16 s +/- 8%

A

1.28

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17
Q

Should you add therefore statements to all half-life questions

A

Yes

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18
Q

What is meant by half-life?

A

The interval of time required for one half of the atomic nuclei of a radioactive sample to decay

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19
Q

What is matter?

A

anything that has mass and occupies space
- composed of atoms

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20
Q

What are protons charge, location and mass in atomic units

A

+, in nucleus, and around 1.0 U

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21
Q

What are neutron charge, location and mass in atomic units

A

neutral, in nucleus, and around 1.0 U

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22
Q

What are electron charge, location and mass in atomic units

A

-, outside, and 0.000540

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23
Q

Do electrons orbit around a nucleus?

A

No, they are found within discrete volume of space called an orbital

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24
Q

What is atomic mass

A

Number of protons and neutrons

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25
Q

What is atomic number

A

number of protons and electrons

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26
Q

What is an isotope?

A

Has same number of protons (atomic #), but different number of neutrons (atomic mass)

  • All isotopes of carbon have same chemical properties, just different masses
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27
Q

What happens as you add neutrons?

A

Becomes less stable

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28
Q

What are radioisotopes?

A

They have an unstable nucleus and emit subatomic particles or energy as they decay into more stable atoms

29
Q

What are the radioactive emissions?

A
  • alpha particles
  • beta particles
  • gamma rays
30
Q

What are alpha particles?

A
  • a helium nucleus
31
Q

What can stop alpha particles?

A

Can be stopped by a sheet of paper

32
Q

What are beta particles?

A

High speed electrons

33
Q

What can stop beta particles?

A

Can be stopped by a sheet of lead

34
Q

What are gamma rays

A
  • energetic electromagnetic radiation
35
Q

How can gamma rays be stopped?

A

A brick of lead

36
Q

What are some uses of radioisotopes?

A
  • Trace movement of carbon through biological pathways like respiration and photosynthesis
  • Measures rate of bone formation
  • Used to date fossils
  • Taken up by thyroid gland gland can be imaged to detect abnormalities
  • Emits radiation that can destroy living cells used to treat cancer tumours
37
Q

What type of radioisotopes are preferred in medicine?

A
  • Short half-life times are preferred as longer exposure can be harmful to cells
38
Q

How are radioisotopes used in medicine?

A
  • Inject radioactive material into patient and track its movement in the body (see how brain works and bones)
  • Energy emitted from radioactive decay can be directed to a tumour
39
Q

What are the positive and negatives of radioisotopes in medicine?

A

Positive:
- Can track brain activity, bone activity if using the right molecules to latch on to radioisotopes, tumours with high-energy radioisotopes

Negative:
- Can damage healthy cells

40
Q

What are tracers?

A

They are a radioisotope placed in the body on a BIOLOGICALLY ACTIVE molecule (glucose, water or ammonia), they give off gamma rays as they decay and are easily detectable (biologically active gos to certain areas and picks up gamma rays shows on images)

41
Q

What are intramolecular bonds?

A

Within the molecule

42
Q

What are three types of intramolecular bonds

A

Ionic, covalent and polar covalent bonds

43
Q

What are ionic bonds?

A
  • Ionic bonds occurs when there is a transfer of one of more electrons from one atom to another (when they lose or gain electrons to form a stable octet)
  • The transfer leads to a formation of a cation and an anion
  • Resulting electrostatic attraction between these two oppositely charged ions forms an ionic bond
  • Ex. NaCl
44
Q

How do radioisotopes help with scientific research?

A
  • Geological and biological research because they study the steady rate of decay
  • Provides info about age of organic materials, rocks and fossils
45
Q

What are covalent bonds?

A

Not strong enough to take electrons so they share it between atoms to achieve a stable electron configuration (stable octet)
Ex. two hydrogen atoms combine to form a molecule of hydrogen gas (equal sharing of electrons so bond is pure covalent)

46
Q

What is the VSEPR Theory?

A

Electrons push each other away forming different molecular shapes

47
Q

What is a polar covalent bond?

A

Occurs when there is an unequal sharing of electrons within a molecule
For example, in water polar bonds are formed because O has a greater attraction for shared electrons (electronegativity) than H

48
Q

What is electronegativity?

A

Ability to pull on electrons

49
Q

The type of bond that forms is determined by the difference in electronegativites of the two atoms involved

A

If there is essentially no difference (<0.5) then the bond is covalent

If there is a different between 0.5 and 1.7, the bond is polar covalent

If the difference is equal to or greater than 1.7, the bond is ionic

50
Q

If a molecule contains polar bonds, does it make it a polar molecule?

A

NO!

51
Q

What is polar molecule?

A

Has a slight positive charge on one side and slightly negative charge on other (unequal distribution) of charge

52
Q

How does one determine is a molecule is polar or non-polar?

A
  1. Draw a Lewis Diagram for each atom
  2. Determine structural formula if molecule
  3. Does molecule have a positive end and a negative end?
  4. Look at symmetry
53
Q

Are polar molecules good solvents?

A

Yes, because they can disrupt ionic bonds with the slightly negative and positive ends

  • When salt and water are mixed, the negative end of water molecules are attracted to the Na+, while the positive end of water are attracted to Cl-
  • Water molecules form “spheres of hydration” around ions, causing the salt to dissolve
54
Q

What are intermolecular bonds?

A

Between compounds (hold two or more molecules together, forces of attraction)

55
Q

Which are stronger intramolecular or intermolecular forces?

A

Intramolecular

56
Q

What are types of intermolecular forces?

A
  • London forces
  • Dipole-dipole forces
  • Hydrogen bonds
57
Q

What are intermolecular bonds also known as

A

Van der Waals forces

58
Q

What are London Forces?

A
  • Cause bonds that are formed due to temporary unequal distribution of electrons in an atom
  • Very weal, occur between small NONPOLAR molecules
  • Cumulative effect of London forces become more significant in large non polar molecules
59
Q

What are dipole-dipole forces?

A
  • Occur between polar molecules like HCl
  • The slightly positive end of one polar molecule is attracted to slightly negative end of another polar molecule
  • Stronger than London Forces
60
Q

What are hydrogen bonds?

A
  • Very strong dipole-dipole
  • Form between electropositive H of one polar molecule and an electronegative N, O, or F of another
61
Q

What are similarities and differences between intramolecular and intermolecular

A

Intramolecular:
- Bonds within molecule
- Strong attraction between atoms
- Stronger than intermolecular
- Commonly called “bonds”
- Determines if electrons are transferred or shared

Intermolecular:
- Bonds within two or more molecules
- Weak attraction between molecules
- Direct implication on state
- Known as “Van der Waal” forces

62
Q

What are some unique properties of water?

A
  • Hydrogen bonding and the angular shape of a water molecule gives it its unique properties essential to existence of living things
  1. Water is an excellent solvent
  2. High heat capacity
  3. Water is both cohesive and adhesive
  4. Water has a high heat conductivity
  5. Water has a high boiling/freezing point
  6. Water is more dense as a liquid then as a solid
63
Q

In what ways do hydrogen bonds produce attractive forces between molecules?

A

By lining up partially positive charged hydrogen atoms with negative charged atoms of diff molecules

64
Q

How do hydrogen bonds influence the physical properties of water?

A

Hydrogen bonds give water a high heart capacity, high boiling/freezing points, high surface tension, cohesion and adhesion

65
Q

What are dehydration and hydrolysis?

A

Dehydration: removal of OH and H from 2 reactant molecules, which allows the reactant molecules to form a bond, as well as creating water

Hydrolysis: breaking of a bond between subunits and the addition of water in the form of OH and H to the subunits

66
Q

What is reduction and oxidation?

A

Redox reactions

Reduction: gains electrons (becomes more negative)
Oxidation: loses electrons

67
Q

Water is a polar molecule. Explain how the polarity of water accounts for its lattice structure

A
  • Helps the formation of hydrogen bonds among water molecules, hydrogen bonds create the lattice structure
68
Q

How does the structure of water account for its properties, such as its boiling point, surface tension and adhesion?

A

Water’s lattice stricture is stable which leads to a high specific heat of water. High specific heat gives water a high boiling point. Water has the ability to form H-bonds with other polar molecules, which gives water its adhesion properties

69
Q

How does polarity influence waters role as a solvent?

A
  • Polar water molecules can surround polar biological molecules or ions, thus dissolving them
  • Water is poor at dissolving non polar molecules

Biology-12 (8 decks)

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