BIO Chapter 2 Practice Questions
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Questions and Answers

In the term trace element, what does the adjective trace mean?

The element is required in very small amounts.

Compared with 31P, what does the radioactive isotope 32P have?

One more neutron.

What gives rise to the reactivity of an atom?

The existence of unpaired electrons in the valence shell.

True or False: All atoms that are anions have more electrons than protons.

<p>True</p> Signup and view all the answers

What does equilibrium in a chemical reaction mean?

<p>The rates of the forward and reverse reactions are equal.</p> Signup and view all the answers

Which notation represents the 18O isotope of oxygen?

<p>8p+, 10n0, 8e-</p> Signup and view all the answers

What is the molecular formula for hydrogen sulfide formed by sulfur combining with hydrogen?

<p>H2S</p> Signup and view all the answers

What coefficients must be placed in the following reaction: C6H12O6 S _____ C2H6O + _____ CO2?

<p>2; 2</p> Signup and view all the answers

What is true regarding essential elements and living organisms?

<p>Although all forms of life require iron, other elements are required only by certain species.</p> Signup and view all the answers

True or False: Concentrations of trace elements above what is required generally have no effect on organisms.

<p>False</p> Signup and view all the answers

True or False: Compounds containing oxygen are not greenhouse gases.

<p>False</p> Signup and view all the answers

There are __________ naturally occurring elements.

<p>92</p> Signup and view all the answers

What is a trace element?

<p>Copper</p> Signup and view all the answers

What are the four most abundant elements found in living systems?

<p>Hydrogen, oxygen, nitrogen, carbon</p> Signup and view all the answers

Which of the following has negligible mass?

<p>Electron</p> Signup and view all the answers

Which subatomic particle has appreciable mass and lacks a charge?

<p>Neutron</p> Signup and view all the answers

The number of protons in an uncharged atom __________.

<p>equals the number of electrons</p> Signup and view all the answers

An element has eight protons, nine neutrons, and eight electrons. Its atomic number and atomic mass, respectively, are __________.

<p>8 and 17</p> Signup and view all the answers

An uncharged atom of nitrogen (atomic number = 7) has __________.

<p>seven protons and seven electrons</p> Signup and view all the answers

In which of the following will isotopes of an element always differ?

<p>Atomic mass</p> Signup and view all the answers

A particular carbon isotope has an atomic number of 6 and an atomic mass of 14. The respective number of neutrons, protons, and electrons that this carbon isotope has is __________.

<p>8, 6, 6</p> Signup and view all the answers

Phosphorus-32 (radioactive) has __________ than phosphorus-35 (normal).

<p>3 fewer neutrons</p> Signup and view all the answers

What would be an isotope of calcium?

<p>An atom with 20 protons, 21 neutrons, and 20 electrons</p> Signup and view all the answers

Why are radioactive isotopes useful in scientific research?

<p>Because they can be used as tracers to follow particular atoms and molecules through metabolic pathways.</p> Signup and view all the answers

A neutral atom of chlorine has an atomic number of 17. It has __________ electrons in its third shell.

<p>7</p> Signup and view all the answers

The chemical characteristics or reactivity of an element depend mostly on the __________.

<p>number of electrons in its outermost shell</p> Signup and view all the answers

These similarities in chemical properties result when different elements have similar __________.

<p>numbers of outer-shell electrons</p> Signup and view all the answers

How many electrons would be present in the valence shell of a sulfur atom (atomic number 16, mass number 32)?

<p>6 electrons</p> Signup and view all the answers

For most atoms, when is a stable configuration of electrons attained?

<p>When the atom has eight electrons in its outermost shell.</p> Signup and view all the answers

An atom that normally has __________ in its outer shell would NOT tend to form chemical bonds with other atoms.

<p>8 electrons</p> Signup and view all the answers

Consider a hypothetical atom with an atomic number of 4 and a net charge of +1. How many neutrons does this ion have?

<p>The answer cannot be determined from the information provided.</p> Signup and view all the answers

When pairs of valence electrons are shared by two neutral atoms, what type of bond is formed?

<p>A covalent bond</p> Signup and view all the answers

A covalent bond is likely to be polar if __________.

<p>one of the atoms sharing electrons is much more electronegative than the other.</p> Signup and view all the answers

When the proton number and electron number are unequal, the atom or molecule __________.

<p>is an ion</p> Signup and view all the answers

What would result if an uncharged copper atom lost two electrons?

<p>The atomic number would remain 29, the mass number would remain 64, and the atom would be a cation with a +2 charge.</p> Signup and view all the answers

What charge would you expect on the sulfate ion after ionization of CaSO4?

<p>-2</p> Signup and view all the answers

Ionic bonds form as a result of __________.

<p>attraction between ions that have opposite charges</p> Signup and view all the answers

A hydrogen bond __________.

<p>is a weak chemical bond.</p> Signup and view all the answers

When do hydrogen bonds occur?

<p>When partial opposite charges on molecules come close enough to attract each other.</p> Signup and view all the answers

What is the role of van der Waals interactions in biological molecules?

<p>Although they are weak bonds, van der Waals interactions help to reinforce the three-dimensional shapes of large molecules.</p> Signup and view all the answers

Which molecule has the shape of a completed tetrahedron?

<p>Methane (CH4)</p> Signup and view all the answers

What chemical property of a molecule is most important for blocking receptor proteins?

<p>The molecule's shape</p> Signup and view all the answers

Which statement is true about chemical reactions?

<p>They involve the making and breaking of chemical bonds.</p> Signup and view all the answers

What characterizes a reversible reaction that has reached chemical equilibrium?

<p>The rate of the reverse reaction equals the rate of the forward reaction.</p> Signup and view all the answers

How many electrons are involved in a single covalent bond?

<p>2</p> Signup and view all the answers

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by _____.

<p>polar covalent bond</p> Signup and view all the answers

Why do Minneapolis and Portland have different climates despite being at the same latitude?

<p>The ocean near Portland moderates the temperature.</p> Signup and view all the answers

If you change the number of neutrons in an atom, what do you create?

<p>An isotope</p> Signup and view all the answers

Which of the following can be attributed to water's high specific heat?

<p>A lake heats up more slowly than the air around it.</p> Signup and view all the answers

Study Notes

Trace Elements and Isotopes

  • Trace elements are required by organisms in very small amounts.
  • The radioactive isotope 32P has one more neutron than 31P.
  • Isotopes of the same element differ in atomic mass and neutron count.

Atomic Structure and Behavior

  • Reactivity of an atom is due to unpaired electrons in its valence shell.
  • Anions have more electrons than protons, leading to a negative charge.
  • The atomic number indicates the number of protons, while atomic mass is the sum of protons and neutrons.

Chemical Reactions and Equilibrium

  • Chemical reactions at equilibrium have equal rates for forward and reverse reactions.
  • The law of conservation of mass dictates that all atoms are accounted for in chemical reactions.

Essential Elements in Biology

  • Essential elements vary across life forms, but all require elements like iron.
  • Naturally occurring elements total 92, with only a few being considered trace elements.

Electrons and Chemical Bonds

  • Electrons largely determine atomic reactivity and bonding behaviors.
  • For most atoms, a stable electron configuration is achieved with eight electrons in the outermost shell.
  • A covalent bond forms when pairs of valence electrons are shared between atoms.

Ionic and Hydrogen Bonds

  • Ionic bonds arise from the attraction of oppositely charged ions.
  • Hydrogen bonds are weak and occur due to partial charges.
  • Van der Waals interactions help stabilize biological molecule structures despite being weak.

Molecular Geometry and Properties

  • The molecular shape, such as a tetrahedron in methane (CH4), is pivotal in biological interactions.
  • Water’s high specific heat allows it to absorb heat without significant temperature changes, affecting local climates.

Isotopes and Radioactive Applications

  • Radioactive isotopes, like phosphorus-32, are used in research to trace metabolic pathways in organisms.
  • Changing the number of neutrons in an atom creates isotopes, which can have varied stability and utility in scientific contexts.

Key Biological Concepts

  • The number of protons in a neutral atom equals the number of electrons, maintaining charge balance.
  • Compounds can exhibit emergent properties, which may differ significantly from their elemental components.

Additional Facts

  • Electrons have negligible mass compared to protons and neutrons, which have appreciable mass.
  • Sulfur has six valence electrons, risking similar chemical behavior with elements that share similar outer-shell electron configurations.

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Test your knowledge with these practice questions from Biology Chapter 2. This quiz covers essential concepts including trace elements, isotopes, and atomic reactivity. Challenge yourself to see how well you understand the material!

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