Principles of Life and Biological Chemistry

Flashcards covering the fundamental principles of living systems, biological history, scientific methodology, and the chemical basis of life, including atomic structure and macromolecules.

According to the transcript, approximately how long ago did the common ancestor of all life on Earth live?

Almost $4$ billion years ago.

What specific green pigment in plant leaves captures solar energy for use in photosynthesis?

Chlorophyll.

What are the three primary domains into which all living organisms are classified?

Archaea, Bacteria, and Eukarya.

In biological nomenclature, such as for the species ‘Homo sapiens,’ what do the first and second words represent?

The first word identifies the genus and the second word indicates the species.

What specific process is hypothesized to have led to the origin of mitochondria and chloroplasts in eukaryotic cells?

Endosymbiosis, which involves larger cells ingesting smaller ones without breaking them down.

What is the term for structural, physiological, or behavioral traits that enhance an organism's survival and reproduction in its environment?

Adaptations.

In the context of scientific methodology, what is the difference between an independent variable and a dependent variable?

The independent variable is the factor being manipulated by the investigator, while the dependent variable is the response that is measured.

What is a ‘null hypothesis’ in statistical testing?

The premise that any observed differences in an experiment are simply the result of random chance.

Which six elements compose approximately $98$ percent of the mass of every living organism?

Carbon ($C$), Oxygen ($O$), Hydrogen ($H$), Phosphorus ($P$), Nitrogen ($N$), and Sulfur ($S$).

What is the standard unit of measure for the mass of an atom, roughly equal to the mass of a single proton or neutron?

The dalton ($Da$).

What are variants of an element that have the same number of protons but different numbers of neutrons called?

Isotopes.

What is the ‘octet rule’ regarding atomic stability for elements with atomic numbers between $6$ and $20$?

An atom will lose, gain, or share electrons to achieve a stable configuration of $8$ electrons in its outermost shell.

What type of chemical bond is characterized by the sharing of one or more pairs of electrons between atoms?

Covalent bond.

What is the term for the attractive force an atomic nucleus exerts on electrons within a covalent bond?

Electronegativity.

What property of water refers to its capacity to resist coming apart when placed under tension?

Cohesion.

What is the difference between hydrophilic and hydrophobic molecules?

Hydrophilic molecules are polar and interact/dissolve in water, while hydrophobic molecules are nonpolar and aggregate together to avoid water.

Which type of reaction links monomers together to form a polymer by removing a water molecule?

Condensation.

What is the primary energy storage compound in plants versus the primary energy storage molecule in mammals?

Plants primarily store energy as starch, while mammals primarily store energy as glycogen.

How do saturated fatty acids differ from unsaturated fatty acids in terms of chemical structure and physical state at room temperature?

Saturated fatty acids have no double bonds in their hydrocarbon chains, allowing them to pack tightly and remain solid; unsaturated fatty acids contain double bonds that create kinks, preventing tight packing and making them liquid.

What does the second law of thermodynamics state about energy transformations?

In any energy transformation, some energy becomes unavailable for work (entropy) and the total free energy decreases.