Comprehensive Biology Review: Chemical Context, Evolution, Themes, and Cell Structure

Flashcards covering chemical foundations of life, evolutionary theory, core biological themes, and cell structure from Campbell Biology.

Which four chemical elements make up approximately $96\%$ of living matter in organisms?

Carbon ($C$), hydrogen ($H$), oxygen ($O$), and nitrogen ($N$).

What is the difference between an element's atomic number and its mass number?

An element's atomic number is the number of protons in its nucleus, whereas its mass number is the sum of protons plus neutrons in the nucleus.

What chemical concept is illustrated by the reaction shown where elemental sodium ($Na$) and chlorine gas ($Cl$) combine to form table salt ($NaCl$)?

Emergent properties, which occur when a compound possesses distinct physical and chemical characteristics different from those of its constituent elements.

What defines a polar covalent bond?

A covalent bond where one atom is more electronegative than the other, resulting in an unequal sharing of electrons and creating a partial negative charge ($\delta-$) on the electronegative atom and a partial positive charge ($\delta+$) on the other.

How does a hydrogen bond form between water ($H_2O$) and ammonia ($NH_3$) as depicted in this figure?

The partial positive charge ($\delta+$) on a hydrogen atom covalently bonded to oxygen in water is attracted to the partial negative charge ($\delta-$) on the electronegative nitrogen atom in ammonia.

When is chemical equilibrium reached in a reversible chemical reaction?

When the forward and reverse reactions occur at the exact same rate, causing the relative concentrations of reactants and products to remain constant.

What contribution did Carolus Linnaeus make to the field of evolutionary biology and taxonomy?

Carolus Linnaeus founded taxonomy—the branch of biology concerned with naming and classifying organisms—and developed the two-part, or binomial, format for naming species.

What mechanism did Jean-Baptiste de Lamarck propose for evolution, and how does modern science view it?

Lamarck hypothesized that species evolve through the use and disuse of body parts and the inheritance of acquired characteristics; this proposed mechanism is unsupported by scientific evidence.

What evolutionary process is demonstrated by the derivation of cabbage, broccoli, kale, brussels sprouts, and kohlrabi from wild mustard?

Artificial selection, in which humans modify species over generations by selectively breeding individuals that possess desired traits.

What are Charles Darwin's two main inferences regarding natural selection?

1) Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring. 2) The unequal ability of individuals to survive and reproduce leads to the gradual accumulation of favorable traits in a population over generations.

What evolutionary relationship is represented by the structural similarities in the forelimbs of humans, cats, whales, and bats?

Homology, specifically homologous structures that represent anatomical variations on a structural theme present in a common ancestor.

How did soapberry bug beak lengths change in central Florida following the introduction of the goldenrain tree?

Beak lengths evolved to become shorter in less than $35$ years to match the smaller seed depth within the fruits of the introduced goldenrain tree.

What is convergent evolution?

The independent evolution of similar, or analogous, features in distantly related lineages as an adaptation to similar environments, rather than through shared ancestry.

What are the five unifying themes of biology outlined in Chapter 1?

Organization, Information, Energy and Matter, Interactions, and Evolution.

How do energy flow and chemical cycling differ within an ecosystem according to this model?

Energy flows through an ecosystem in one direction (entering as light and exiting as heat), whereas chemical nutrients cycle within an ecosystem and are continuously recycled.

How does negative feedback regulate blood glucose levels as shown in this diagram?

High blood glucose stimulates the pancreas to secrete insulin, which causes body and liver cells to store glucose; as blood glucose levels drop, stimulus for insulin secretion diminishes.

What is the primary structural difference between eukaryotic and prokaryotic cells?

Eukaryotic cells contain membrane-enclosed organelles including a membrane-bounded nucleus, whereas prokaryotic cells lack a nucleus (DNA is in an unbound nucleoid region) and membrane-bound organelles.

What is the function of a control group in a controlled scientific experiment?

A control group serves as an unmanipulated baseline to compare against the experimental group, ensuring that changes in the dependent variable are due strictly to the manipulation of the independent variable.

What geometric principle governs the relationship between cell size, surface area, and total volume?

As a cell increases in size, its volume grows proportionally faster ($r^3$) than its surface area ($r^2$), resulting in a decreased surface-to-volume ratio that limits metabolic transport.

What are the primary metabolic functions of the Smooth Endoplasmic Reticulum (Smooth ER)?

Synthesizing lipids, metabolizing carbohydrates, detoxifying drugs and poisons, and storing calcium ions.

What is the functional difference between the cis face and trans face of the Golgi apparatus?

The cis face acts as the receiving side for transport vesicles arriving from the ER, whereas the trans face acts as the shipping side that dispatches vesicles to other destinations.

What process describes a lysosome fusing with a food vacuole to break down engulfed cellular material?

Phagocytosis.

What evolutionary process is illustrated by this diagram regarding the origins of mitochondria and chloroplasts?

The Endosymbiont Theory, which posits that early ancestors of eukaryotic cells engulfed nonphotosynthetic and photosynthetic prokaryotes that evolved into mitochondria and chloroplasts.

What are the three main structural components of the eukaryotic cytoskeleton, ordered from smallest to largest in diameter?

Microfilaments (actin filaments, $\approx 7\,nm$), Intermediate filaments ($8\text{--}12\,nm$), and Microtubules (tubulin polymers, $\approx 25\,nm$).

What motor protein powers the bending movement of motile cilia and flagella?

Dynein.

Which three types of cell junctions are commonly found connecting neighboring epithelial cells in animal tissues?

Tight junctions (prevent fluid leakage across cell layers), Desmosomes (anchor cells together into strong sheets), and Gap junctions (provide cytoplasmic channels between adjacent cells).