Chemistry of Life Chapter 3

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Questions and Answers

What does a pH value of 7 indicate about a solution?

The solution is highly acidic.

The solution releases more hydroxide ions than hydrogen ions.

The solution is strongly basic.

The solution contains equal concentrations of hydrogen and hydroxide ions. (correct)

How can a substance be classified as an acid?

It does not affect the ion concentration in water.

It increases the concentration of hydroxide ions in a solution.

It releases hydrogen ions in a solution. (correct)

It has a pH value greater than 7.

What happens to the pH of a solution when more hydroxide ions are introduced?

The pH increases, becoming more basic. (correct)

The pH stays the same, remaining neutral.

The pH becomes extremely alkaline.

The pH decreases, becoming more acidic.

Which of the following correctly describes the pH scale?

A lower pH value corresponds to a stronger acid. Signup and view all the answers

Which characteristic is true of a basic solution?

It has more hydroxide ions than hydrogen ions. Signup and view all the answers

What is the primary measurement unit for mass?

Grams Signup and view all the answers

How does gravity affect weight compared to mass?

Weight changes with gravity, but mass remains constant. Signup and view all the answers

Which of the following correctly describes solids?

They have a definite shape and volume. Signup and view all the answers

What happens to your weight on the Moon compared to Earth?

It is one-sixth of your weight on Earth. Signup and view all the answers

What is the smallest unit of an element that retains its properties?

An atom Signup and view all the answers

What is the core of an atom called?

Nucleus Signup and view all the answers

Which subatomic particles are found in the nucleus of an atom?

Protons and neutrons Signup and view all the answers

What defines isotopes of an element?

They have different numbers of neutrons. Signup and view all the answers

What is the primary role of proteins within cells?

They provide structure, transport molecules, and catalyze reactions. Signup and view all the answers

How are amino acids linked together in proteins?

By dehydration synthesis. Signup and view all the answers

What determines the unique properties of each amino acid?

The side-chain group at R. Signup and view all the answers

What is formed when one or more polypeptide chains come together?

Functional proteins. Signup and view all the answers

Which of the following actions describes the process of dehydration synthesis in protein formation?

Linking amino acids together while releasing water. Signup and view all the answers

Which of the following statements about polypeptide chains is true?

They consist of a specific sequence based on genetic instructions. Signup and view all the answers

What is the basic building block of proteins?

Amino acids. Signup and view all the answers

Which function is NOT associated with proteins?

Storing genetic information. Signup and view all the answers

What is the primary function of hydrolysis in sugar metabolism?

To break down larger sugar molecules into monosaccharides Signup and view all the answers

Which sugar does sucrose break down into during hydrolysis?

Glucose and fructose Signup and view all the answers

What is the primary storage form of glucose in animals?

Glycogen Signup and view all the answers

Why can most animals not digest cellulose?

The type of bonds between glucose molecules are indigestible Signup and view all the answers

How do plants store glucose produced during photosynthesis?

As starch in various parts of the plant Signup and view all the answers

What role does cellulose play in plant cells?

Providing rigidity to plant cells Signup and view all the answers

During digestion, carbohydrates are primarily broken down into what?

Monosaccharides Signup and view all the answers

Which food group is least likely to contain carbohydrates?

Meat Signup and view all the answers

What does the atomic number of an element signify?

The number of protons in the nucleus of an atom Signup and view all the answers

How does the periodic law relate to elements and their atomic numbers?

It indicates that the properties of elements are a periodic function of their atomic numbers. Signup and view all the answers

Which of the following elements is NOT one of the four most common in living organisms?

Iron Signup and view all the answers

What is true about isotopes of a given element?

They have the same number of protons but different numbers of neutrons. Signup and view all the answers

In what form do sodium and other elements circulate in the body?

As ions Signup and view all the answers

What can be concluded about carbon-12 and carbon-14?

They are isotopes of carbon with different neutron counts. Signup and view all the answers

What is the mass number of an atom determined by?

The sum of the number of protons and neutrons Signup and view all the answers

Which statement about electrons in an atom is correct?

Electrons counterbalance the charge of protons in a neutral atom. Signup and view all the answers

What mainly differentiates fats from oils at room temperature?

The types of bonds between carbon atoms Signup and view all the answers

What structural feature of triglycerides influences whether they are classified as fats or oils?

The type of bonds between the carbon atoms Signup and view all the answers

How does the presence of saturated bonds in fats affect their physical state at room temperature?

They remain solid Signup and view all the answers

What is the main storage form of fat in the body?

Adipose tissue Signup and view all the answers

How do unsaturated bonds in oils affect their physical state at room temperature?

They remain liquid Signup and view all the answers

Why do triglycerides float in the bloodstream?

They are less dense than water Signup and view all the answers

What causes adipose tissue to increase in size?

Addition of more fat molecules Signup and view all the answers

What elements compose both sugars and fats?

Carbon, hydrogen, oxygen Signup and view all the answers

What happens to triglycerides when they are stored in adipose tissue?

They undergo a chemical rearrangement Signup and view all the answers

Which statement correctly describes the effect of bonding types in fats and oils?

Fats are solid due to tight packing of saturated bonds. Signup and view all the answers

Study Notes

Chapter 3: The Chemistry of Life

Everything with mass and takes up space is matter
Matter is composed of atoms
Atoms form molecules, which compose living things
Important molecules include carbohydrates, proteins, nucleic acids, and lipids
Living things need matter to grow and build structures
Matter is recycled throughout the environment
Matter existed since the Earth was formed

Exploring Why Matter Matters

Matter is the substance of life
Living things require matter to build new structures
Matter is recycled after living things die
All matter on Earth has existed since the planet's formation
Matter from all living organisms can be found in a single object

Invisible Matter

Air, though seemingly nothing, is actually matter, composed of gases
Plants take in carbon dioxide, an invisible component of air, to create food
Invisible matter like carbon dioxide can become part of a living thing, having mass

Atoms, Elements, and Isotopes

All matter is composed of elements
Elements are composed of atoms
Atoms consist of smaller subatomic particles (protons, neutrons, electrons)
Isotopes are atoms with a different number of neutrons
Carbon-12 and carbon-14 are two isotopes of carbon

Bohr's Model of Atoms

An atom is the smallest piece of an element
Atoms have a nucleus comprised of protons and neutrons
Electrons orbit the nucleus
Protons have a positive charge
Neutrons have no charge
Electrons have a negative charge
Atoms become ions when they lose or gain electrons (positive or negative charge)

Elements of Elements

An element is composed of atoms with the same number of protons
The periodic table arranges elements by their atomic number
Atomic number represents the number of protons in an atom
Elements have similar properties when arranged according to their atomic number

Atoms and Ions

Atoms combine to have oppositely charged ions, joining together with ionic bonds
Sodium and chloride ions (atoms) forming table salt (NaCl) is an example of ionic bonds

Covalent Bonds

Atoms share electrons to form covalent bonds
Oxygen atoms sharing electrons to form oxygen gas (O2) is an example of covalent bonds

Acids and Bases

Acids release hydrogen ions in water (H+)
Bases release hydroxide ions in water (OH-)
Acid-base reactions can affect chemical bonds in living organisms

pH Scale

The pH scale measures hydrogen ion concentration in a solution
Solutions with more hydrogen ions than hydroxide ions are acidic (lower than 7)
Solutions with more hydroxide ions than hydrogen ions are basic (higher than 7)
A pH of 7 is neutral, like pure water
Buffers are substances that help keep solutions stable by neutralizing excess hydrogen or hydroxide ions

Carbon-Based Molecules (The Basis for All Life)

Living organisms use many types of molecules, including hydrocarbons
Carbohydrates are made of carbon, hydrogen, and oxygen
Carbohydrates are frequently used as a quick energy source
Carbohydrates include monosaccharides, disaccharides, oligosaccharides, and polysaccharides
Monosaccharides are simple sugars such as glucose
Disaccharides are double sugars, such as sucrose
Oligosaccharides are short chains of simple sugars
Polysaccharides are long chains of simple sugars

Making Life Possible: Proteins

Proteins are polymers of amino acids
Proteins have many functions, including structure, transport, and enzymes

Drawing the Cellular Road Map: Nucleic Acids

Nucleic acids carry genetic information
Nucleic acids, like DNA, are composed of nucleotides
Nucleotides have three parts (nitrogenous base, sugar, phosphate group)
DNA is a double-stranded molecule, while RNA is single-stranded
DNA contains the nitrogenous bases adenine, guanine, cytosine, and thymine
RNA contains the nitrogenous bases adenine, guanine, cytosine, and uracil

Deoxyribonucleic Acid (DNA)

DNA is a critical component for passing down genetic information to the next generation
DNA is composed of paired nitrogenous bases (adenine with thymine, and guanine with cytosine) along a sugar-phosphate backbone
The order of nitrogenous bases form a gene, which contains genetic information

Ribonucleic Acid (RNA)

RNA is another vital component of carrying out genetic information
RNA has a structure different from DNA
RNA uses uracil instead of thymine
RNA is single-stranded, holding genetic information

Supplying Structure, Energy, and More: Lipids

Lipids are molecules that don't mix with water
Lipids are a source of energy
Lipids include phospholipids, steroids, and triglycerides
Phospholipids form cell membranes
Steroids are often hormones
Triglycerides are mostly a source of storage of energy for the organism

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Description

This quiz covers Chapter 3: The Chemistry of Life, focusing on the fundamentals of matter and its importance in living organisms. It delves into the composition of matter, the role of atoms and molecules, and how matter is recycled within ecosystems. Test your understanding of key concepts including invisible matter and the various molecules necessary for life.