biol 171 lec 1

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Questions and Answers

What percentage of the weight of most cells is made up by the 'big four' elements?

70%

96% (correct)

80%

99%

Which of the following elements is NOT one of the 'big four' that makes up about 96% of the weight of most cells?

Oxygen

Hydrogen

Phosphorus (correct)

Carbon

What is the percentage of Carbon in the elements of life?

20.0%

65.0%

18.5% (correct)

9.5%

Which of the following elements is present in the highest percentage in the elements of life?

Oxygen Signup and view all the answers

What is the function of the control system in an organism?

To maintain homeostasis Signup and view all the answers

How many essential elements are required by organisms?

25 Signup and view all the answers

What determines how an atom will interact with other atoms?

The number of electrons in the outer electron shell Signup and view all the answers

What type of bond forms when two atoms share one or more electrons?

Covalent bond Signup and view all the answers

What is the definition of an ion?

An atom with an electrical charge due to gain or loss of electron(s) Signup and view all the answers

What is the result of an atom losing or gaining electrons to achieve a full outer electron shell?

Formation of an ion Signup and view all the answers

What is the strongest type of chemical bond?

Covalent bond Signup and view all the answers

What is the product of the reaction between sodium and chlorine?

Sodium chloride (NaCl) Signup and view all the answers

What is the characteristic of atoms that form ionic bonds?

They are oppositely charged Signup and view all the answers

What is the reason atoms form chemical bonds?

To achieve a full outer electron shell Signup and view all the answers

What is electronegativity?

An atom's ability to attract electrons Signup and view all the answers

What type of covalent bond is formed when electrons are shared equally?

Nonpolar covalent bond Signup and view all the answers

What is the polarity of the water molecule?

Polar Signup and view all the answers

What is the function of hydrogen bonds in water molecules?

To create weak electrical attractions between molecules Signup and view all the answers

What is the result of the unequal sharing of electrons in a covalent bond?

Partial charges Signup and view all the answers

What increases from left to right in a row in the periodic table?

Electronegativity Signup and view all the answers

What type of bond is formed between hydrogen atoms and the oxygen atom in a water molecule?

Polar covalent bond Signup and view all the answers

What is the term for the weak electrical attraction between neighboring water molecules?

Hydrogen bond Signup and view all the answers

What is the characteristic of carbon skeletons in macromolecules?

They may be unbranched or branched and have double bonds. Signup and view all the answers

What is the process by which monomers are linked together to form a polymer?

Dehydration reaction Signup and view all the answers

What is the term for the building blocks or subunits of macromolecules?

Monomers Signup and view all the answers

What is the characteristic of organic molecules?

They are based on carbon Signup and view all the answers

What is the term for the large molecules found in all living creatures?

Macromolecules Signup and view all the answers

What are the four main categories of macromolecules?

Carbohydrates, lipids, proteins, and nucleic acids Signup and view all the answers

What is the primary function of epithelial cells in the body?

To facilitate selective secretion and absorption of ions and organic molecules Signup and view all the answers

What is the main characteristic of simple epithelial cells?

Single cell layer thick Signup and view all the answers

What is the primary function of connective tissue cells in the body?

To provide structural support and anchor the body's structures Signup and view all the answers

What type of connective tissue is responsible for storing energy in the body?

Adipose Signup and view all the answers

What is the primary function of the extracellular matrix (ECM)?

To provide a scaffold for cellular attachments and transmit information to cells Signup and view all the answers

What is the basic structure of an organ?

Multiple types of tissue Signup and view all the answers

What is the relationship between organs and organ systems?

Organ systems are composed of multiple organs Signup and view all the answers

What is the term for the immediate environment that surrounds each individual cell in the body?

Extracellular fluid and extracellular matrix (ECM) Signup and view all the answers

Study Notes

Elements of Life

Carbon (C) makes up 18.5% of the weight of most cells
Oxygen (O) makes up 65.0% of the weight of most cells
Four elements (C, O, H, and Ca) make up about 96% of the weight of most cells
The remaining 25 essential elements are needed in smaller amounts
Trace elements make up less than 0.01% of the weight of most cells

Atomic Structure

Electrons are organized in electron shells
The outer electron shell is the most important
A full outer electron shell means a stable atom
The number of electrons in the outer electron shell determines how an atom will interact with other atoms

Chemical Bonds

Atoms lose, gain, or share electrons to fill their outermost electron shell
Atoms react with other atoms to form molecules
Ionic bonds: oppositely charged ions attract
Covalent bonds: two atoms share one or more electrons

Ionic Bonds

Ion: an atom with an electrical charge due to gain or loss of electron(s)
Sodium atom (Na) loses an electron to become a sodium ion (Na+)
Chlorine atom (Cl) gains an electron to become a chloride ion (Cl-)

Covalent Bonds

Covalent bonds: the strongest bond
Electrons are not always shared equally
Atoms joined into a molecule via covalent bonds
Electronegativity: an atom's ability to attract electrons
Electronegativity increases from left to right in a row in the periodic table

Water Molecule

Water molecule (H2O): a very important polar molecule
Hydrogen bonds: weak electrical attraction between neighboring water molecules
Hydrogen bonds give water unique properties

Origin of Life

Macromolecules: large molecules found in all living creatures
Organic molecules: carbon-based molecules
Carbon is the most important element for life
Carbon skeletons vary in length and may have double bonds or be arranged in rings

Molecules of Life

Macromolecules include: carbohydrates, lipids, proteins, and nucleic acid
Most macromolecules have a unique monomer
Monomers are linked together through covalent bonds to produce a polymer via dehydration reactions

Connective Tissue Cells

Connective tissue cells are specialized to connect, anchor, and support the structures of the body
Types of connective tissues include: loose connective, dense connective, blood, bone, cartilage, and adipose

Extracellular Matrix (ECM)

ECM consists of a mixture of proteins, polysaccharides, and in some cases, minerals
The matrix serves two general functions: provides a scaffold for cellular attachments and transmits information to the cells to help regulate their activity

Organs and Organ Systems

Organs are composed of multiple tissue types
Organ systems contain multiple organs that work together
There are 11 different organ systems in the human body

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Test your understanding of fundamental biology concepts, including the elements of life, homeostasis, and evolution.