What is biology?

The scientific study of life.

What are the characteristics of life?

Living organisms have organization, use energy, maintain homeostasis, reproduce, and evolve.

What is the functional unit of life?

The cell.

how do plants get energy

They convert solar energy into a chemical form.

What is homeostasis?

The process by which an organism maintains a constant internal environment.

What are the two types of reproduction?

Asexual and sexual reproduction.

What is evolution?

The process that leads to the diversity of life on Earth through changes in genetic information.

What is chemistry?

A scientific discipline that studies the properties and behavior of matter.

What is the smallest unit of matter?

The atom.

What are the three types of subatomic particles?

Protons, neutrons, and electrons.

What charge do protons have?

A positive electrical charge.

What charge do electrons have?

A negative electrical charge.

What is the atomic nucleus?

Protons and neutrons packed together tightly in a dense core.

What is the atomic number?

The number of protons in the nucleus of an element.

What is the mass number?

The total number of protons and neutrons in the nucleus of an atom.

What is an element?

A substance that cannot be broken down into other substances by chemical reactions.

What four elements make up 96% of all living matter?

Oxygen, carbon, hydrogen, and nitrogen.

What is a molecule?

A substance consisting of two or more elements linked with covalent bonds.

What is a neutron?

A subatomic particle that is electrically neutral.

What is a proton?

A subatomic particle with one unit of positive charge.

What is an electron?

A subatomic particle with one unit of negative charge.

What are isotopes?

Atoms of the same element that have different numbers of neutrons.

What is an example of a common carbon isotope?

12C, which has six protons and six neutrons.

What is a characteristic of unstable isotopes?

They can spontaneously transform protons into neutrons and vice versa.

What is an unstable isotope?

An unstable isotope has protons and neutrons that can spontaneously transform into each other, emitting radiation.

What is an example of carbon isotopes?

Carbon-12, Carbon-13, and Carbon-14 are isotopes of carbon.

What is a radioactive isotope?

A radioactive isotope has a nucleus that decays spontaneously, emitting particles and energy.

What happens when a radioactive carbon atom decays?

It transforms into an atom of nitrogen.

What is one medical application of radioactive isotopes?

Radioactive tracers are used as diagnostic tools in medical imaging.

What is a chemical bond?

A chemical bond is a strong attractive force connecting two atoms through the loss, gain, or sharing of electrons.

What are valence electrons?

Valence electrons are the electrons in the outermost shell that participate in chemical reactions.

What are the two types of bonding relevant to biology?

Ionic bonds and covalent bonds.

What is an ionic bond?

An ionic bond occurs when two charged ions stick together due to opposite charges.

What is a covalent bond?

A covalent bond is the sharing of a pair of valence electrons between two atoms.

What is electronegativity?

Electronegativity is the attraction of an atom for the electrons in a covalent bond.

What is the difference between nonpolar and polar covalent bonds?

Nonpolar bonds involve equal sharing of electrons, while polar bonds involve unequal sharing.

Why is water considered a polar molecule?

Water is polar because oxygen is more electronegative than hydrogen, causing unequal sharing of electrons.

What is an anion?

An anion is a negatively charged ion that has gained an electron.

What is a cation?

A cation is a positively charged ion that has lost an electron.

What is a hydrogen bond?

A hydrogen bond is a weak attraction between a hydrogen atom with a partial positive charge and an electronegative atom.

What is a hydrophilic molecule?

A hydrophilic molecule has an affinity for water and can interact with polar molecules.

What is a hydrophobic molecule?

A hydrophobic molecule has a fear of water and does not interact with polar molecules.

What is hydrogen bonding in water?

Hydrogen bonding in water occurs due to the attraction between the slight positive charge of hydrogen and the slight negative charge of oxygen.

What type of interaction is a hydrogen bond?

A hydrogen bond is an attraction between polar molecules due to slight opposite charges on hydrogen and oxygen atoms.

What atoms can hydrogen bonds form with?

Hydrogen bonds can form between hydrogen atoms and electron-greedy atoms such as oxygen, nitrogen, sulfur, and fluorine.

How strong are hydrogen bonds compared to covalent or ionic bonds?

Hydrogen bonds are relatively weak and form and break easily compared to covalent or ionic bonds.

What role do hydrogen bonds play in water molecules?

Hydrogen bonds form in large numbers among water molecules, contributing to water's unique properties.

What is cohesion in relation to water?

Cohesion is the phenomenon of collective hydrogen bonds holding water together, leading to surface tension.

How does cohesion affect water movement in plants?

Cohesion allows columns of liquid water to rise from roots to leaves in narrow pipelines in plants.

What is adhesion in relation to water?

Adhesion is the ability of water to stick to other surfaces, such as water beads on a flower petal.

How does adhesion affect water movement in a straw?

Adhesion causes water to climb up a straw when placed in a glass of water.

What is the significance of water's high specific heat?

Water's high specific heat allows it to absorb and store large amounts of heat with minimal temperature change.

How do hydrogen bonds contribute to water's high specific heat?

Hydrogen bonds absorb and release heat, causing a small temperature change when heat is added or removed.

What happens to water molecules when water freezes?

When water freezes, molecules lock together in a lattice structure, making ice less dense than liquid water.

Why does ice float on water?

Ice floats because it is about 10% less dense than liquid water due to the structure formed by hydrogen bonds.

What would happen if ice sank?

If ice sank, ponds and lakes would freeze solid, endangering aquatic life.

What is evaporation?

Evaporation is the process in which molecules escape from the surface of a liquid and become vapor.

How does hydrogen bonding affect evaporation?

Hydrogen bonding resists evaporation, requiring energy to overcome cohesion among water molecules.

What is the heat of vaporization?

The heat of vaporization is the amount of heat required to convert 1 g of a liquid into gas.

How does evaporation help regulate temperature in plants?

Evaporation from leaves helps keep plant tissues cool in sunlight.

How does sweating help regulate human body temperature?

Sweating cools the body by evaporating water from the skin, dissipating heat.

What is the role of ice in insulating water bodies?

Ice insulates the water below, preventing it from freezing solid and allowing life to exist beneath.

Why is 4°C a critical temperature for water?

At 4°C, water behaves like other liquids, but below this temperature, it begins to freeze.

What is a solvent?

A solvent is the dissolving agent in a solution.

What is a solution?

A solution is a homogenous mixture of two or more substances.

What is a solute?

A solute is the substance that is dissolved by the solvent.

What is an aqueous solution?

An aqueous solution is one in which water is the solvent.

In a sugar and coffee mixture, which is the solvent?

In coffee with added sugar, water is the solvent.

What keeps ice less dense than water?

Hydrogen bonds keep the molecules far enough apart.

In the coffee and sugar example, which is the solvent?

Coffee is the solvent.

In the coffee and sugar example, which is the solute?

Sugar is the solute.

Why is water considered a fine solvent?

Because of its polarity, it can dissolve ionic compounds and polar molecules.

What are hydrophilic substances?

Substances that have an affinity for water.

What are hydrophobic substances?

Substances that repel water and cannot form hydrogen bonds.

Give an example of a hydrophilic substance.

Cotton.

Give an example of a hydrophobic substance.

Vegetable oil.

Why does oil float on water?

Oil molecules cannot form hydrogen bonds with water.

What ions does water spontaneously break apart into?

Positively charged hydrogen ions (H+) and negatively charged hydroxide ions (OH-).

What is the pH of a neutral solution?

7.

What indicates an acidic solution?

More H+ ions than OH− ions, with a pH below 7.

What indicates a basic solution?

Fewer H+ ions and more OH− ions, with a pH above 7.

How does a buffer stabilize pH?

By accepting or donating hydrogen ions to minimize changes in concentration.

What are macromolecules?

Large molecules essential for life, including nucleic acids, carbohydrates, proteins, and lipids.

What is a monomer?

A single subunit of a polymer.

What is a polymer?

A chain of monomers.

What is dehydration synthesis?

The process of joining monomers together to form a polymer.

What is hydrolysis?

The process of breaking down a polymer into monomers using water.

What is a carbohydrate?

An organic compound consisting of carbon, hydrogen, and oxygen in a 1:2:1 ratio.

What are monosaccharides?

Single sugar molecules that are water-soluble.

What is a disaccharide?

A carbohydrate chain of two monomers.

What is an oligosaccharide?

A carbohydrate chain of approximately three to six monomers.

What is a polysaccharide?

A long chain containing hundreds or thousands of monomers.

What is cellulose?

The most abundant organic molecule on Earth, a structural polysaccharide made by plants.

What is starch?

A polysaccharide that stores energy in plants.

What is glycogen?

A polysaccharide that stores energy in animals.

Where is most glycogen stored in the body?

In muscle and liver cells.

What is glycogen primarily stored in?

Muscle and liver cells.

How many valence electrons does carbon have?

4

How many bonds can carbon form?

4

What type of bonds does carbon form with other elements?

Covalent bonds.

What are four ways that carbon skeletons can vary?

Length, branching, double bond position, and presence of rings.

What is a functional group?

A chemical group that affects molecular function by being directly involved in chemical reactions.

What is the property of the amino group?

Polar and hydrophilic.

What is the property of the carboxylic group?

Polar and hydrophilic.

What is the property of the hydroxyl group?

Polar and hydrophilic.

What is the property of the methyl group?

Nonpolar and hydrophobic.

What is the property of the phosphate group?

Polar and hydrophilic.

What is the property of the carbonyl group?

Polar and hydrophilic.

What is the property of the sulfhydryl group?

Polar and hydrophilic.

What are the four main classes of large molecules found in living things?

Carbohydrates, lipids, proteins, nucleic acids.

Define macromolecule.

Extremely large molecules, sometimes consisting of thousands of atoms.

What are macronutrients?

Carbohydrates, proteins, and lipids that provide energy.

What type of reaction connects monomers?

Dehydration reaction.

What occurs during hydrolysis?

A polymer is broken down with water added between the monomers.

What are the monomers of all carbohydrates?

Monosaccharides or simple sugars.

What is a glycosidic linkage?

A covalent bond formed between two monosaccharides by a dehydration reaction.

Name three common monosaccharides.

Glucose, fructose, and galactose.

What are the two categories of polysaccharides?

Storage (starch, glycogen) and structural (cellulose, chitin).

Why can humans not digest cellulose?

Human enzymes cannot hydrolyze the beta linkages of cellulose.

What is glucose?

A simple monosaccharide.

What is fructose?

A monosaccharide commonly called 'fruit sugar'.

What is lactose?

'Milk sugar'.

What is chitin?

A structural polysaccharide that gives cockroaches their crunch.

What is maltose?

Malt sugar used to brew beer.

What is a protein?

A molecule that contains amino acids linked together in a chain.

What is the monomer form of protein?

Amino acid.

What is a peptide bond?

A covalent bond in which two amino acids are joined by a dehydration reaction.

What is a dipeptide?

A polymer of two amino acids linked by a peptide bond.

What is a polypeptide?

A polymer of many amino acids linked by a peptide bond.

What is a disulfide bridge?

Links between the sulfhydryl groups of two cysteine amino acids.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary.

Why is hemoglobin said to have quaternary structure?

It consists of four polypeptide subunits.