BIO 181: Properties of Water and pH Scale

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Questions and Answers

What is the smallest unit of biological organization that retains the characteristics of life?

Atom

Molecule

Cell (correct)

Organism

What forms the basic hierarchical organization of living organisms?

Non-living building blocks (correct)

Multicellular structures

Complex tissues

Single-celled organisms

What are the highly-organized assemblies of non-living molecules that make up cells?

Chemicals (correct)

Tissues

Genes

Cells

In the context of biological organization, which level is immediately lower than that of a cell?

Biomolecule Signup and view all the answers

What aspect makes the composition of life unique compared to non-living matter?

Complex organization of molecules Signup and view all the answers

Which of the following atoms would you find in a significant component of living organisms?

Oxygen Signup and view all the answers

What percentage of the composition of the human body is attributed to carbon?

18% Signup and view all the answers

The composition of life is primarily made up of which type of elements?

Non-living molecules Signup and view all the answers

What happens to an excited-state electron after it becomes unstable?

It returns to its ground state by releasing a photon of light. Signup and view all the answers

What is the significance of the electron configuration in an atom?

It dictates the chemical properties and interactions with other atoms. Signup and view all the answers

Why can't the exact position of an electron be determined at a given moment?

The complexities of the speed of light complicate measurements. Signup and view all the answers

What are the types of chemical bonds primarily discussed as forming molecules?

Ionic and covalent bonds. Signup and view all the answers

What occurs when two atoms form a chemical bond?

They fill their valence shells to achieve stability. Signup and view all the answers

What does the pH scale primarily reflect?

The concentration of hydrogen ions in an aqueous solution Signup and view all the answers

In an ionic bond, what charge does the atom that donates an electron acquire?

It becomes positively charged. Signup and view all the answers

What type of atoms typically participate in ionic bonding?

Metals and nonmetals. Signup and view all the answers

What do acids do to biological molecules?

They add hydrogen ions to biological molecules. Signup and view all the answers

Why is carbon such an essential element for life?

It can form four covalent bonds due to its valence shell. Signup and view all the answers

What role do subshells play in an atom's structure?

They create the overall shape of the atom. Signup and view all the answers

What characterizes organic molecules in relation to carbon?

They incorporate regular patterns of functional groups bonded to carbon. Signup and view all the answers

What impact do strong acids and bases have on biological molecules?

They alter the structure of biological molecules. Signup and view all the answers

What is the significance of the four bonding positions of a carbon atom?

They allow for structural diversity in organic macromolecules. Signup and view all the answers

What is the main role of functional groups in organic molecules?

They determine the molecule's reactivity and properties. Signup and view all the answers

What distinguishes macromolecules from smaller organic molecules?

Macromolecules have high variability in structure due to long chains of carbon. Signup and view all the answers

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

Protons and neutrons Signup and view all the answers

Which of the following accurately describes isotopes?

Atoms of an element with different numbers of neutrons Signup and view all the answers

How do electrons fill the electron shells in an atom?

In order of increasing energy, from lowest to highest Signup and view all the answers

What is the purpose of unstable isotopes in geology and archaeology?

Dating materials radiometrically Signup and view all the answers

Which statement about the model of the atom developed by Niels Bohr is incorrect?

All shells have the same energy level Signup and view all the answers

What happens to an electron when it absorbs a photon of light energy?

It is boosted to a higher energy shell Signup and view all the answers

What primarily defines the nature of a polar covalent bond?

Unequal sharing of electrons due to differences in electronegativity Signup and view all the answers

Which statement about water's properties is NOT true?

Ice floats because it is denser than liquid water. Signup and view all the answers

Why are some isotopes considered unstable?

They decay at a relatively constant rate Signup and view all the answers

How do covalent bonds contribute to a molecule's shape?

The arrangement and type of covalent bonds influence the overall geometry of the molecule. Signup and view all the answers

Which of the following elements would typically have six protons and seven neutrons?

Carbon-14 Signup and view all the answers

What occurs when table salt (NaCl) dissolves in water?

The Na+ and Cl- ions dissociate and become solutes in the aqueous solution. Signup and view all the answers

Which of the following best explains why water has strong surface tension?

Cohesion between water molecules leads to strong interactions at the surface. Signup and view all the answers

Which characteristic of water contributes to its role as a solvent for polar molecules?

Water's polar nature and ability to form hydrogen bonds Signup and view all the answers

Why is the unique property of ice being less dense than liquid water crucial for life?

It allows ice to form habitats for various organisms. Signup and view all the answers

Which factor best describes electronegativity in the context of covalent bonds?

The attraction that an atom's nucleus has for shared electrons Signup and view all the answers

Study Notes

Properties of Water and the pH Scale

pH scale measures hydrogen ion (H+) concentration in solutions.
Acids possess high H+ ion concentrations, affecting biological molecules like proteins and lipids.
Bases have low H+ concentrations and can remove H+ ions from biological molecules.
Alteration of biological molecules occurs when exposed to strong acids/bases.

Importance of Carbon in Organic Chemistry

Carbon is the second most abundant element in living organisms, crucial for life's molecular structure.
A carbon atom needs four valence electrons, leading to the formation of four covalent bonds.
Organic molecules consist of carbon chains and various functional groups influencing their functions.

Structure of Macromolecules

Long carbon chains form diverse organic macromolecules contributing to structural and functional versatility.
Recognizing functional groups aids in understanding molecular behavior and properties.

Biological Organization

Living organisms exhibit a hierarchical structure starting from non-living components.
Cells are the fundamental units of biological organization, capable of sustaining life's characteristics.

Composition of Life

Cells comprise organized assemblies of non-living molecules containing various atoms (e.g., C, O, N, H).
Differences in elemental composition exist between living organisms and non-living matter.

Atomic Structure Overview

Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells.
Isotopes vary in neutron numbers, affecting stability and allowing for applications in dating and energy generation.

Chemical Bonds

Atoms form molecules through chemical bonds that stabilize their valence shells.
Ionic bonds arise from electron transfer between metals and nonmetals, creating cations and anions.
Covalent bonds occur through the sharing of electron pairs, helping achieve stable configurations.

Electronegativity and Molecular Polarity

Electronegativity refers to an atom’s affinity for shared electrons; larger atoms are generally more electronegative.
The molecular structure determines polarity; polar molecules interact better with other polar substances.

Properties of Water

Water is less dense in its solid state (ice) compared to liquid, vital for aquatic ecosystems.
Serves as an excellent solvent for polar molecules and ions, facilitating biochemical reactions.
Cohesion contributes to high surface tension, while adhesion aids in capillary action, promoting nutrient transport in plants.
Water has a high specific heat, stabilizing environmental temperatures essential for life.

Solutions and Dissolution

Dissolution involves solute particles dispersing in a solvent; e.g., NaCl dissociates into Na+ and Cl- in water.
Solubility patterns differ; polar solutes like sugar dissolve differently than ionic compounds due to their distinct interactions with water molecules.

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Description

This quiz focuses on the properties of water and the pH scale, highlighting the concentration of hydrogen ions in solutions. It explores the roles of acids and bases in biological systems, specifically how they interact with biological molecules like proteins and lipids. Test your understanding of these fundamental concepts in general biology!