biology (chapter 2-chemistry)

Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?

10 (atomic mass is equal to the number of protons plus the number of neutrons (199=10)

How many electrons would be expected in the outermost electron shell of an atom with atomic number 12?

2

How many electrons can the first shell hold?

2 electrons

What is the approximate atomic mass of an atom with 16 neutrons, 15 protons, and 15 electrons?

31

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many electrons does boron have?

5

An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?

5 (the atomic number is equal to the number of protons)

What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?

6

outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.

A covalent chemical bond is one in which

Solute

A dissolved substance.

ph

A measure of the concentration of H+ in a solution.

polar molecule

A molecule in which electrons are not shared equally between atoms, causing a partial negative charge at one end and a partial positive charge at the other. Water is a polar molecule.

polymer

A molecule made up of individual subunits, called monomers, linked together in a chain.

Electron

A negatively charged subatomic particle with negligible mass.

cell membrane

A phospholipid bilayer with embedded proteins that forms the boundary of all cells.

Proton

A positively charged subatomic particle in the nucleus of an atom.

proton

A positively charged subatomic particle in the nucleus of an atom.

prions

A protein-only infectious agent.

elements

A pure substance that cannot be chemically broken down; each element is made up of and defined by a single type of atom.

ionic bond

A strong electrical attraction between oppositely charged ions formed by the transfer of one or more electrons from one atom to another.

covalent bond

A strong interaction resulting from the sharing of a pair of electrons between two atoms.

solvent

A substance in which other substances can dissolve. Water is a good solvent.

acids

A substance that increases the hydrogen ion concentration of solutions, making them more acidic.

Bases

A substance that reduces the hydrogen ion concentration of solutions, making them more basic.

phospholipids

A type of lipid that forms the cell membrane.

hydrogen bonds

A weak electrical attraction between a partially positive hydrogen atom and an atom with a partial negative charge.

molecule

A(n)___ refers to two or more atoms held together by covalent bonds.

carbon, hydrogen, nitrogen, oxygen

About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter?

8 electrons

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

ions

An electrically charged atom, the charge resulting from the loss or gain of electrons.

Neutron

An electrically uncharged subatomic particle in the nucleus of an atom.

8 and 17

An element has 8 protons, 9 neutrons, and 8 electrons. Its atomic number and atomic mass, respectively, are _____.

Virus

An infectious agent made up of a protein shell that encloses genetic information.

Protein

An organic molecule made up of linked amino acid subunits.

protein

An organic molecule made up of linked amino acid subunits.

Carbohydrates

An organic molecule made up of one or more sugars.

matter

Anything that takes up space and has mass.

Molecule

Atoms linked by covalent bonds.

molecules

Atoms linked by covalent bonds.

20 protons

Calcium has an atomic number of 20 and an atomic mass of 40. Therefore, a calcium atom must have

Which of the following is a trace element?

Copper (accounts for less than 0.01% of living matter)

What is the difference between covalent bonds and ionic bonds?

Covalent bonds involve the sharing of electrons between atoms, and ionic bonds involve the electrical attraction between atoms.

organic

Describes a molecule with a carbon-based backbone and at least one C—H bond.

atomic number

Each element is unique and different from other elements because of the number of protons in the nuclei of its atoms. Which of the following indicates the number of protons in an atom's nucleus?

RNA is single-stranded, whereas DNA is double-stranded. Uracil is used in RNA, whereas thymine is used in DNA.

How do RNA and DNA molecules differ? Select the TWO answers that are correct. -RNA has one fatty acid chain, whereas DNA has two of them. -Adenine is used in RNA, whereas cytosine is used in DNA. -RNA contains sugars in its backbone, whereas DNA does not. -RNA is single-stranded, whereas DNA is double-stranded. -Uracil is used in RNA, whereas thymine is used in DNA.

Phospholipids have two fatty acid tails, whereas triglycerides have three.,Phospholipids have a hydrophilic phosphate group in place of one fatty acid tail.

How do triglycerides and phospholipids differ? Select the TWO answers that are correct. -Phospholipids have ribose in place of the deoxyribose used in triglycerides. -Phospholipids have two fatty acid tails, whereas triglycerides have three. -Phospholipids store energy, whereas triglycerides are cell membrane components. -Phospholipids are saturated with hydrogens, whereas triglycerides are unsaturated. -Phospholipids have a hydrophilic phosphate group in place of one fatty acid tail.

The oxygen has a partial negative charge and the hydrogens have a partial positive charge, yielding a weakly polar water molecule that can form hydrogen bonds.

How does the molecular structure of a water molecule affect its polarity? -The oxygen and hydrogen rapidly exchange electrons in their outermost energy shells, producing structures that can form hydrogen bonds. -The oxygen takes an electron from each hydrogen, yielding a negatively charged oxygen and two positively charged hydrogens that can form hydrogen bonds. -The oxygen has a partial negative charge and the hydrogens have a partial positive charge, yielding a weakly polar water molecule that can form hydrogen bonds. -The oxygen donates an electron to each hydrogen, yielding a positively charged oxygen and two negatively charged hydrogens that can form hydrogen bonds. -The oxygen has a partial positive charge and the hydrogens have a partial negative charge, yielding a weakly polar water molecule that can form hydrogen bonds.

Water is a polar molecule that disrupts ionic bonds between sodium and chloride.

How does water dissolve table salt? -Water is a nonpolar molecule that dissolves covalent bonds between sodium and chloride. -Water is a polar molecule that disrupts hydrogen bonds between sodium and chloride. -Water is a polar molecule that takes electrons from sodium chloride. -Water is a nonpolar molecule that breaks the ionic bonds between sodium and chloride. -Water is a polar molecule that disrupts ionic bonds between sodium and chloride.

ionic (sodium and chlorine ions are attracted to each other)

In salt, what is the nature of the bond between sodium and chlorine?

growth and reproduction

One argument explaining why viruses are not living is that viruses depend on the cells of other living creatures in order to multiply. Which characteristics of life does this argument use? Select the TWO answers that are correct. -reproduction -homeostasis -use energy -growth -respond to stimuli

monomers

One chemical subunit of a polymer.

nucleic acids

Organic molecules made up of linked nucleotide subunits; DNA and RNA are examples of nucleic acids.

lipids

Organic molecules that generally repel water.

8 protons

Oxygen has an atomic number of 8 and a mass number of 16. thus, the number of protons oxygen has is

Ice would sink rather than float, so there would be no ice sheets or ice bergs.

Polar bears rely on Arctic ice sheets and icebergs on the surface of water as a part of their habitat. How would the habitat of polar bears be affected if solid water was more dense than liquid water? -Permanent ice would form on the surface, creating more habitat for polar bears. -Ice would sink rather than float, so there would be no ice sheets or ice bergs. -Water would become polar, causing it to freeze more solidly and melt less easily. -Water would stay liquid over a wider temperature range, limiting ice formation. -Water would be unable to freeze at all, causing the total loss of polar bear habitat

Which of the following statements is false? -Atoms of the various elements differ in their number of subatomic particles -All atoms of a particular element have the same #of protons in their nuclei -The neutrons and protons present in the nucleus of an atom are almost identical in mass; each has a mass of about 1 dalton -An atom is the smallest unit of an element that still retains the properties of the element? -Protons and electrons are electrically charged particles. Protons have one unit of neg. charge, and electrons have one unit of pos. charge.

Protons and electrons are electrically charged particles. Protons have one unit of negative charge, and electrons have one unit of positive charge.

Energy

The ability to do work. Living organisms obtain energy either directly from sunlight (through photosynthesis) or from food they consume.

energy

The ability to do work. Living organisms obtain energy either directly from sunlight (through photosynthesis) or from food they consume.

adhesion

The attraction between molecules (or other particles) and a surface.

Cohesion

The attraction between molecules (or other particles).

cell

The basic structural unit of living organisms.

monosaccharides

The building block, or monomer, of a carbohydrate.

Nucleotide

The building block, or monomer, of a nucleic acid.

amino acids

The building block, or monomer, of a protein.

Nucleus

The dense core of an atom.

2

The innermost electron shell of an atom can hold up to ___ electrons

Homeostasis

The maintenance of a relatively constant internal environment.

protons and neutrons

The mass number of an element can be easily approximated by adding together the number of __________ in an atom of that element.

solution

The mixture of solute and solvent.

atomic number

The number of protons in an atom, which determines the atom's identity.

Atom

The smallest unit of an element that still retains the property of the element.

92

There are ___ naturally occurring elements

macromolecules

Very large organic molecules that make up living organisms; they include carbohydrates, proteins, and nucleic acids.

hydrophobic

Water-fearing"; these molecules will not dissolve in water.

hydrophilic

Water-loving"; these molecules dissolve easily in water.

a carbon backbone, a carbon-hydrogen bond

What characteristics make a particular molecule organic? Select the TWO answers that are correct. -a carbon-nitrogen bond -presence of carbon -a carbon backbone -a carbon-hydrogen bond -a carbon-oxygen bond

number of protons and number of neutrons in the nucleus, total number of electrons in orbitals

What determines the identity of a particular atom? Select the TWO answers that are correct. -number of electrons in the inner most energy shell -number of protons and number of neutrons in the nucleus -total number of neutrons in orbitals -number of protons in the outermost energy shell -total number of electrons in orbitals

Acids contain relatively few hydroxide ions, whereas bases contain excess hydroxide ions.

What is the relationship between acids, bases, and hydroxide ions? -Acids contain relatively few hydroxide ions, whereas bases contain excess hydroxide ions. -Acids contain only hydroxide ions, whereas bases contain no hydroxide ions. -Acids contain no hydroxide ions, whereas bases contain only hydroxide ions. -Acids strengthen and bases weaken as hydroxide concentration increases. -Acids contain excess hydroxide ions, whereas bases contain relatively few hydroxide ions.

Hydrogen bonds between water molecules expand when solid

What makes ice less dense than liquid water? -Ionic bonds between water molecules expand when solid. -Nuclear forces form expansive crystals as freezing occurs. -Covalent bonds within water molecules expand when solid. -Hydrogen donates electrons to oxygen as freezing occurs. -Hydrogen bonds between water molecules expand when solid.

covalent

What type of bond is joining the two hydrogen atoms? (electron pairs are shared also)

Protons and neutrons are located in the nucleus, and electrons are located in orbitals.

Where are the protons, neutrons, and electrons located in an atom? -Protons, electrons, and neutrons are located in the nucleus, and energy is located in orbitals. -Protons and electrons are located in the nucleus, and neutrons are located in orbitals. -Electrons and neutrons are located in orbitals, and protons are located in the nucleus. -Electrons and neutrons are located in the nucleus, and protons are located in orbitals. -Protons and neutrons are located in the nucleus, and electrons are located in orbitals.

electrons in the outermost energy shell

Which part of an atom forms covalent bonds with other atoms? -electrons in the innermost energy shell -protons in the innermost energy shell -neutrons in the outermost energy shell -protons in the outermost energy shell -electrons in the outermost energy shell

a weak bond between the slightly negative oxygen atom of one water molecule and the slightly positive hydrogen atoms of another water molecule

Which statement describes a hydrogen bond between two water molecules? -a weak bond in which the oxygen atom of one molecule donates an electron to the hydrogen atom of another water molecule -a weak bond between the slightly positive oxygen atom of one water molecule and the slightly negative hydrogen atoms of another water molecule -a weak bond between the slightly negative oxygen atom of one water molecule and the slightly positive hydrogen atoms of another water molecule -a weak bond in which the oxygen atom of one molecule takes an electron away from the hydrogen atom of another water molecule -a weak bond in which the oxygen atom of one molecule stably shares electrons with the hydrogen atom of another water molecule

drain cleaner, baking soda

Which substances have an alkaline pH? Select the TWO answers that are correct. -orange juice -battery acid -drain cleaner -baking soda -coffee

protect self from predators

Which trait is NOT a functional characteristic of all living things? -grow and reproduce -acquire and consume energy -protect self from predators -maintain homeostasis -sense and respond to stimuli

In the absence of water, sodium and chloride form ionic bonds and aggregate into crystals.

Why do salt crystals form in a pan of seawater from which the water has been evaporated? -In the absence of water, sodium and chloride form ionic bonds and aggregate into crystals. -In the absence of water, sodium and chloride share electrons in a stable bond that permits crystal formation. -In the absence of water, sodium and chloride form covalent bonds and aggregate into crystals. -In the absence of water, sodium and chloride form hydrogen bonds and aggregate into crystals. -In the absence of water, chloride donates electrons to sodium and the compounds aggregate into crystals.

The bilayer is a barrier to some, but not all, substances on either side of it

Why is the phospholipid bilayer considered semipermeable? -Small, nonpolar molecules do not pass through the phospholipid bilayer. -The hydrophobic tails act as a barrier to nonpolar molecules. -Large molecules can only pass through the layer of hydrophilic phospholipids. -The bilayer is completely nonpolar, which prevents some molecules from passing. -The bilayer is a barrier to some, but not all, substances on either side of it.

It separates the cellular environment from the external environment., It acts as a barrier for some, but not all, molecules on either side of it

Why is the phospholipid bilayer important to cell survival? Select the TWO answers that are correct. -It maintains homeostasis by forming an insulating layer around the cell. -It blocks small, nonpolar molecules from entering the cell and harming it. -It anchors nucleotides together as they form molecules of DNA. -It separates the cellular environment from the external environment. -It acts as a barrier for some, but not all, molecules on either side of it.

An ionic bond involves _____.

an attraction between ions of opposite charge

The ionic bond of sodium chloride is formed when

chlorine gains an electron from sodium

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates?

iodine

In salt, what is the nature of the bond between sodium and chlorine?

ionic

A(n)___ refers to two or more atoms held together by covalent bonds

molecule

What do atoms form when they share electron pairs?

molecules

In the term "trace element", the modifier "trace" means?

the element is required in very small amounts

hydrogen bond

what name is given to the bond between water molecules