BIOL 1111 > Chapter 2-3 > Flashcards

Chapter 2-3 Flashcards

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1
Q

What is matter?

A

Anything that has mass and occupies space

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2
Q

What are organisms composed of

A

Matter

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3
Q

What is a chemical element?

A

A substance consisting of only one type of atom.

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4
Q

How many naturally occurring elements exist?

A

92

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5
Q

About how many elements are essential to life?

A

About 25.

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6
Q

What are trace elements?

A

Elements required by organisms in very small amounts.

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7
Q

What is an atom?

A

The smallest unit of matter that retains the properties of an element.

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8
Q

What are the three subatomic particles?

A

Protons, neutrons, electrons.

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9
Q

What charge does a proton have?

A

Positive

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10
Q

What charge does a neutron have?

A

No charge.

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11
Q

What charge does an electron have?

A

Negative

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12
Q

What is the atomic number of an element?

A

The number of protons in the nucleus.

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13
Q

Why is the atomic number important?

A

It uniquely identifies the element.

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14
Q

What is the mass number of an atom?

A

The total number of protons and neutrons.

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15
Q

What are isotopes?

A

Atoms of the same element with different numbers of neutrons.

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16
Q

What is a radioactive isotope?

A

An isotope with an unstable nucleus that releases energy.

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17
Q

Why are radioactive isotopes dangerous?

A

They can damage DNA and cause mutations.

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18
Q

How are radioactive isotopes useful?

A

As tracers in medicine and biological research.

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19
Q

Changing which particle changes an atom into a different element?

A

Protons

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20
Q

What determines how an atom behaves chemically?

A

Its electrons.

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21
Q

What are electron shells?

A

Energy levels where electrons are found.

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22
Q

How many electrons fit in the first shell?

A

Two

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23
Q

How many electrons fit in the second shell?

A

Eight

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24
Q

What are valence electrons?

A

Electrons in the outermost shell.

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25
Why are valence electrons important?
They determine chemical reactivity.
26
What does it mean if an atom has a full valence shell?
It is chemically inert.
27
What is valence?
The number of electrons needed to fill the outer shell.
28
What is the octet rule?
Atoms tend to have eight electrons in their valence shell.
29
What is a chemical bond?
An attraction that holds atoms together.
30
What is a compound?
A substance made of two or more elements in a fixed ratio.
31
Why do compounds have different properties from elements?
Because atoms are arranged differently.
32
What is an ionic bond?
An attraction between oppositely charged ions.
33
How are ions formed?
By gaining or losing electrons.
34
Why do ionic compounds dissolve in water?
Water stabilizes ions due to polarity.
35
What is a covalent bond?
A bond formed by sharing electrons.
36
What is a molecule?
Two or more atoms held together by covalent bonds.
37
What is a double covalent bond?
Sharing of two pairs of electrons.
38
What is electronegativity?
An atom’s attraction for shared electrons.
39
Which atoms are more electronegative: O and N or C and H?
Oxygen and nitrogen.
40
What is a nonpolar covalent bond?
Equal sharing of electrons.
41
What is a polar covalent bond?
Unequal sharing of electrons.
42
Why is water essential for life?
Most biological reactions occur in water.
43
What is the chemical formula of water?
H₂O
44
Why is water a polar molecule?
Oxygen attracts electrons more strongly than hydrogen.
45
What is a hydrogen bond?
A weak attraction between polar molecules.
46
What property causes water molecules to stick together?
Cohesion
47
What is surface tension?
Resistance to breaking the surface of a liquid.
48
Why does water moderate temperature?
Hydrogen bonds absorb and release heat.
49
What is the difference between heat and temperature?
Heat is total energy; temperature is average energy.
50
Why does ice float?
Water expands upon freezing.
51
What is a solution?
A homogeneous mixture of substances.
52
What is a solvent?
The dissolving agent.
53
What is a solute?
The substance dissolved.
54
What does hydrophilic mean?
Water-loving.
55
What does hydrophobic mean?
Water-fearing.
56
What happens when water dissociates?
It forms H⁺ and OH⁻ ions.
57
What is an acid?
A substance that donates H⁺ ions.
58
What is a base?
A substance that accepts H⁺ ions.
59
What is the pH scale range?
0 to 14.
60
What pH is neutral?
7
61
Why are buffers important?
They resist changes in pH.
62
What is a macromolecule?
A large molecule made of many atoms.
63
What is a polymer?
A long molecule made of repeating subunits.
64
What is a monomer?
A building block of a polymer.
65
What reaction builds polymers?
Dehydration synthesis.
66
What reaction breaks polymers?
Hydrolysis.
67
What are carbohydrates?
Sugars and polymers of sugars.
68
What is a monosaccharide?
A single sugar molecule.
69
What is glucose used for?
Primary fuel for cells.
70
What is a disaccharide?
Two monosaccharides linked together.
71
What is a polysaccharide?
A polymer of many sugars.
72
What is starch?
Plant energy storage polysaccharide.
73
What is glycogen?
Animal energy storage polysaccharide.
74
What is cellulose?
Structural polysaccharide in plant cell walls.
75
Why are lipids hydrophobic?
They are mostly nonpolar.
76
What is the main function of fats?
Long-term energy storage.
77
What are saturated fats?
No double bonds; solid at room temperature.
78
What are unsaturated fats?
One or more double bonds; liquid at room temperature.
79
What are phospholipids?
Lipids that form cell membranes.
80
What does amphipathic mean?
Having both hydrophilic and hydrophobic regions.
81
What are steroids?
Lipids with four fused rings.
82
What are proteins made of?
Amino acids.
83
How many amino acids exist?
20.
84
What determines protein function?
Its three-dimensional shape.
85
What is an enzyme?
A protein that speeds up reactions.
86
What is denaturation?
Loss of protein structure and function.
87
What are nucleic acids?
Molecules that store genetic information.
88
What are the two types of nucleic acids?
DNA and RNA.
89
What are nucleotides made of?
Sugar, phosphate, nitrogenous base.
90
What bases are found in DNA?
A, T, C, G.
91
What bases pair together in DNA?
A–T and C–G.
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