Biology II Exam 1

List and define the biological levels of organization

Atoms, molecules, macromolecules, organelles, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, biosphere.

Atoms

Basic units of matter, consisting of protons, neutrons, and electrons.

Molecules

Chemical structures formed by two or more atoms bonded together.

Macromolecules

Large molecules made up of smaller subunits, including proteins, nucleic acids, carbohydrates, and lipids.

Organelles

Specialized structures within cells that perform distinct functions, such as mitochondria and ribosomes.

Cells

The basic structural and functional units of living organisms, capable of performing all life processes. Smallest unit of life

Tissues

Groups of similar cells that work together to perform a specific function in an organism.

Organ

A group of tissues that work together to perform a specific function in an organism. Such as the brain or heart.

Organ system

A group of organs that work together to perform complex functions necessary for the survival of an organism. Such as the nervous system.

Organism

A living entity made up of one or more cells that can carry out life processes. Such as a human being.

Population

A group of individuals of the same species living in a specific area, interacting with each other and their environment. Such as the population of students at Clarkson

Community

A group of different species that live together in a specific area and interact with each other. Such as a group of plants, deer, and bears.

Ecosystem

A biological community of interacting organisms and their physical environment, such as a pond or a forest consisting of animals and plants and rocks and water.

Biosphere

The global sum of all ecosystems, encompassing all living beings and their relationships with the environment. Such as the earth.

List and define the characteristics of life

DNA, Has cells, Energy, Responds to stimuli, Homeostasis, Reproduction, Evolution

DNA

Blueprint for life’s organization, development, and function

Has cells

Is composed of cells; cells are smallest units of life

Energy

The capacity to do work and sustain biological processes, necessary for growth, reproduction, and maintenance of homeostasis.

Responds to stimuli

Organisms react to changes in their environment, demonstrating adaptability and survival.

Reproduction

Organisms Pass genetic information to the next generation

Evolution

Over time, populations evolve and adapt

Biological evolution

A heritable change in one or more characteristics in a population of organisms from one generation to the next.

How does biological evolution explain both the unity and diversity of life?

Through the mechanisms of common descent and natural selection

Common descent

Idea that all living things are descended from a single ancestor

Natural selection

Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success

Evidence for life on Earth as far back as?

4.5 billion years ago

What are changes in the sequence of bases in a DNA molecule known as?

Mutations

Vertical evolution

Mutations passed from parent(s) to offspring via a lineage

Why do mutations accumulate?

Beneficial or deleterious mutations impact survivorship and reproduction via natural selection

Horizontal evolution

Mutations not passed from parent(s) to offspring

Tree of life

Vertical gene transfer only

Web of life

Vertical and horizontal gene transfer

Classification

Grouping living things based on certain criteria

Taxonomy

Provides hierarchical relationships between items. Every species has a scientific name and also have common names. “Genus species“

e.g. Ursus americanus: American black bear

• Genus capitalized and species name is not

• Entire name is italicized

Systematics

Study of the diversity and evolutionary relationships between species

Domains

Highest level of classification for organisms

What are the 3 domains?

Bacteria, Archaea, Eukarya

Bacteria

Unicellular, prokaryotic cell type

Archaea

Also unicellular, prokaryotic cell type

Eukarya

Unicellular, colonial, or multicellular, with eukaryotic cell type

3 lowest levels of organization

• Atoms

• Molecules

• Macromolecules

3 subatomic particles that make up atoms

• Protons - nucleus, positive charge

• Neutrons - nucleus, neutral charge

• Electrons - orbitals, negative charge

Protons

Located in the nucleus, positive charge

Neutrons

Located in the nucleus, neutral charge

Electrons

orbits around the nucleus, negative charge

What happens when the number of protons is equal to the number of electrons?

The atom is electrically neutral

What happens when the number of protons is not equal to the number of electrons?

Forms an ion with a charge

Cations are positive

Anions are negative

Elements

Specific atoms with a specific number of protons

The number of protons in an element is known as?

Atomic number

Atomic mass

Number of protons and neutrons combined

Isotopes

when atoms have an different amount of protons and neutrons

Orbitals

The positions surrounding an atom's nucleus where the electrons are most likely to be at any given moment

Orbitals contain up to two electrons and are nested within electron shells

difference between electron shells and orbitals

Shells represent specific energy levels or electron clouds surrounding the atomic nucleus, while orbitals describe the most likely paths or regions where electrons can be found within a given shell.

Explain how electrons are organized into orbitals and how orbitals are organized into energy levels (or electron shells)

Electrons are organized into orbitals, which are specific regions of space within an atom where an electron is most likely to be found, and these orbitals are grouped together into energy levels (electron shells) based on their relative energy, with lower energy levels closer to the nucleus and higher energy levels further away; each shell contains one or more subshells, which are made up of specific types of orbitals (s, p, d, f) with distinct shapes and orientations. 

Chemical bonding

Process by which atoms or ions are joined together to form molecules

What are valence electrons? How are they involved chemical bonding?

Those in the outermost shell that participate in forming chemical bonds

Octet rule

Most atoms found in living systems have a full outer shell with 8 electrons, except hydrogen (H) which is full with 2 electrons

Which four elements are most common in living systems?

Carbon, hydrogen, oxygen, and nitrogen

Make up 95% of atoms in living organisms

Ionic bond

Transfer of electrons between atoms - cation and anion

Covalent bond

Sharing electrons between atoms - single, double, etc.

Hydrogen bond

Hydrogen interacting with oxygen, nitrogen, or fluorine

Polar

Unequal sharing of electrons

Non-polar

Equal sharing of electrons

Why does polarity matter?

It determines how molecules interact with each other, influencing their solubility, ability to mix with other substances, and overall chemical behavior

Electronegativity

Chemical property of atoms - tendency to attract electrons

Non-polar covalent bonds

Atoms of equal electronegativities, share electrons equally

Polar covalent bonds

Atoms of different electronegativities, more electronegative atom attracts electrons towards its nucleus

Subscripts

Small numbers written below an element symbol within a chemical formula, indicating the number of atoms of that element in a molecule

coefficients

Numbers written in front of a chemical formula, showing how many molecules of that substance are involved in the reaction

Reactants

Starting materials that undergo a chemical change, appearing on the left side of a chemical equation

Products

New substances formed in the reaction, appearing on the right side of the equation

Empirical formula

Simplest whole number ratio (e.g. C2H5)

Molecular formula

Number and type of atoms (C4H10)

Condensed formula

Order and formula of functional groups

Structural formula

Graphic representation of structure

How do chemical reactions occur?

When molecules of different substances collide with enough energy to break their existing bonds, allowing the atoms to rearrange and form new bonds

Metabolism

The sum of all chemical reactions occurring in a cell and/or organism

Why is water the universal biochemical medium?

Because of its unique properties, particularly its polarity and ability to dissolve a wide range of substances, making it crucial for biological processes and evolution. Life formed in aqueous solutions.

How much of a human is water?

65%

How much of a plant is water?

95%

What kind of bond is a water molecule?

Polar covalent bond - oxygen is more electronegative than hydrogen, attracts electrons towards its nucleus. Due to its polarity, water readily forms hydrogen bonds.

3 properties of matter

Solid, liquid, gas

Hydrophilic molecules

Molecules that can interact with water

Hydrophobic molecules

Nonpolar substances that repel water and do not dissolve in it

Amphipathic molecules

A compound comprising a hydrophilic head and a hydrophobic tail

Explain the pH scale

Measures how acidic or basic a substance is, ranging from 0 (very acidic) to 14 (very basic), with a neutral point at 7 (water)

Describe the relationship between water and pH

pH is a measure of how acidic or basic water is, with a value of 7 indicating neutral water, while a pH below 7 is acidic and above 7 is basic; essentially, the pH of water reflects the balance between hydrogen ions (H+) and hydroxide ions (OH-) present in the water, with more H+ ions creating an acidic solution and more OH- ions creating a basic solution. 

How do acids behave in a solution?

By releasing hydrogen ions (H+) into the solution

How do bases behave in a solution?

Dissociate to produce hydroxide ions (OH-) which can react with hydrogen ions (H+) from acids to form water

Compare how acids and bases behave in solution

Acids release hydrogen ions (H+) into the solution, increasing its acidity, while bases release hydroxide ions (OH-) which decrease the acidity (or increase the alkalinity) of the solution

Why is pH important in living systems?

It significantly impacts the function of enzymes and other proteins, which are essential for most biological processes

Buffer

A solution that can resist pH change upon the addition of an acidic or basic components

What role do buffers play in living systems?

By maintaining a stable pH level by readily absorbing excess hydrogen or hydroxide ions

How many valence electrons does a carbon atom have?

4

Why is carbon an ideal atom to use as a backbone for building large, complex biological molecules?

It has four valence electrons, allowing it to form stable covalent bonds with up to four other atoms simultaneously

Organic molecules

Molecules that are made of carbon and hydrogen, and can include other elements

Hydrocarbon skeletons

Composed entirely of carbon atoms linked together, forming a chain or ring structure, which serves as the backbone for the molecule with hydrogen atoms attached to the carbon atoms at available bonding sites

Functional groups

Specific groupings of atoms within molecules that have their own characteristic properties, regardless of the other atoms present in a molecule

Monomers

Atoms or small molecules that bond together to form more complex structures such as polymers

Polymers

Any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, which are multiples of simpler chemical units called monomers