Comprehensive Life Sciences & Microbiology Study Guide for Students

What are the 8 characteristics of life?

1. Made of Cells, 2. Display Organization, 3. Growth and Development, 4. Reproduction, 5. Respond to Stimuli, 6. Require Energy (Metabolism), 7. Maintain Homeostasis, 8. Evolve and Adapt.

What is the basic structural unit of life?

Cells

What is the difference between unicellular and multicellular organisms?

Unicellular organisms consist of a single cell, while multicellular organisms are made up of multiple cells.

What does 'Display Organization' refer to in living organisms?

It refers to the hierarchical arrangement of structures, from cells to tissues to organs to organ systems.

What is the difference between growth and development in organisms?

Growth is an increase in mass/size, while development involves changes in shape, structure, or function over an organism's life cycle.

What are the two types of reproduction?

Sexual reproduction (involving two parents and genetic variation) and asexual reproduction (involving one parent and clonal copies).

How do organisms respond to stimuli?

Organisms react to external or internal environmental changes, such as a plant bending toward light.

What is metabolism?

The sum of all chemical reactions in an organism that convert nutrients into energy.

What is homeostasis?

The ability of an organism to maintain a stable internal environment despite changes in external conditions.

What does it mean for a population to evolve and adapt?

Over generations, populations develop adaptations that enhance survival in changing environments.

What are the levels of biological organization?

Molecular Level → Cellular Level → Tissue Level → Organ Level → Organ System Level → Organism Level.

What defines prokaryotic cells?

Prokaryotic cells are simpler, lack a nucleus, and are typically smaller than eukaryotic cells.

What defines eukaryotic cells?

Eukaryotic cells have a true nucleus and membrane-bound organelles.

What is the size range of prokaryotic cells?

Typically 0.1-5.0 micrometers.

What is the size range of eukaryotic cells?

Typically 10-100 micrometers.

How is DNA organized in prokaryotic cells?

DNA is concentrated in a nucleoid region and is typically a single, circular chromosome.

How is DNA organized in eukaryotic cells?

DNA is organized into multiple, linear chromosomes wrapped around histone proteins.

What is the function of ribosomes in cells?

Ribosomes are the site of protein synthesis.

What is the role of the Golgi apparatus?

It modifies, sorts, and packages proteins and lipids for transport.

What is the function of mitochondria?

Mitochondria are responsible for cellular respiration and ATP production.

What is the function of chloroplasts?

Chloroplasts conduct photosynthesis, converting solar energy into chemical energy.

What is the difference between plant and animal cells regarding cell wall?

Plant cells have a rigid cell wall made of cellulose; animal cells do not.

What is the function of lysosomes?

Lysosomes are involved in intracellular digestion and breaking down worn-out organelles.

What is the secretory pathway in cells?

It is the process where proteins are synthesized in the rough ER, modified in the Golgi apparatus, and secreted from the cell.

What is photosynthesis?

The process by which autotrophs convert solar energy, carbon dioxide, and water into glucose, releasing oxygen.

What is cellular respiration?

The process by which cells break down glucose in the presence of oxygen to produce ATP, carbon dioxide, and water.

What are the inputs and outputs of photosynthesis?

Inputs: 6CO2 + 6H2O + Light Energy; Outputs: C6H12O6 + 6O2.

What are the inputs and outputs of cellular respiration?

Inputs: C6H12O6 + 6O2; Outputs: 6CO2 + 6H2O + ATP Energy.

What are biotic factors in an ecosystem?

The living or once-living parts of an ecosystem that influence organisms, such as prey, predators, and competitors.

What are abiotic factors?

The non-living, physical and chemical components of an environment (e.g., temperature, sunlight, water availability).

Define species.

A group of structurally similar organisms capable of interbreeding in nature to produce viable, fertile offspring.

What characterizes a biome?

A vast geographic area characterized by distinct regional climates, soil types, and climax communities of plants and animals.

What is biodiversity?

The total variety of all life forms, genetic variations, and ecosystem complexities within a given habitat or across the entire biosphere.

Define habitat.

The distinct, physical environment or geographical area where an organism naturally lives and grows.

What is a niche?

An organism's total functional role, resource requirements, and behavioral space within its habitat.

Describe predator/prey relationships.

An ecological interaction where one organism (the predator) hunts, kills, and consumes another organism (the prey).

What is carrying capacity ($K$)?

The maximum population size of a species that a specific ecosystem can sustainably support long-term.

What is a keystone species?

A species that exerts strong control on the structure and biodiversity of an entire community relative to its abundance.

List the trophic levels in an ecosystem.

Producers, Primary Consumers, Secondary Consumers, Tertiary Consumers.

What are producers?

Organisms that make their own food from inorganic materials using solar or chemical energy.

Define consumers.

Organisms that cannot manufacture their own food and must acquire energy by ingesting other living things.

What are primary consumers?

Herbivores that eat producers directly (e.g., rabbits, deer).

What are secondary consumers?

Carnivores or omnivores that eat primary consumers (e.g., frogs, snakes).

What are tertiary consumers?

Apex predators that consume secondary consumers (e.g., hawks, killer whales).

What is a food chain?

A single, linear pathway tracing the direct transfer of food energy from producers up through successive consumers.

Define food web.

A complex network of multiple food chains that maps out all realistic feeding pathways within an ecosystem.

What does the 10% Law of Energy Transfer state?

Only about 10% of energy is stored as biomass when transferred to the next trophic level; the rest is lost as heat or waste.

What is exponential growth?

Rapid population growth that occurs under idealized conditions with unlimited resources and no competition.

Define logistic growth.

Realistic growth that begins exponentially but slows as resources become depleted and competition intensifies.

What are density-dependent factors?

Limiting factors whose impact depends on the population density, intensifying as population numbers climb.

What are density-independent factors?

Limiting factors that affect a population regardless of its size or density (e.g., natural disasters).

What is ecological succession?

The predictable process of structural change and species replacement in a community over time following a disturbance.

What is primary succession?

The colonization of a barren area where no pre-existing soil exists, such as after a volcanic eruption.

Define pioneer species.

The first organisms to colonize barren landscapes, typically lichens and mosses.

What is secondary succession?

The re-colonization of an ecosystem following a disturbance that leaves the soil intact.

What is a climax community?

The final, stable ecological community that marks the end point of succession.

Define symbiosis.

A close, prolonged physical interaction between individuals of two different species.

What is mutualism?

An obligatory or elective relationship where both species benefit significantly from the interaction.

Provide an example of mutualism.

Bees gathering nectar while cross-pollinating flowers.

What is commensalism?

A relationship where one species benefits while the other is neither helped nor harmed.

Give an example of commensalism.

Barnacles cementing themselves to a whale's skin for transport.

Define parasitism.

A destructive relationship where one organism benefits at the expense of another, the host.

Provide an example of parasitism.

Tapeworms in a mammal's digestive tract.

What is bioaccumulation?

The gradual buildup of a non-biodegradable, fat-soluble toxin in an individual organism's tissues.

What is biomagnification?

The cumulative increase in toxin concentration as it passes up through successive trophic levels of a food chain.

What is taxonomy?

The science of naming, defining, and organizing groups of biological organisms based on shared characteristics.

What is the significance of phylogenetics in taxonomy?

It groups organisms based on how recently they shared a common ancestor using molecular DNA sequencing.

Differentiate between homologous and analogous structures.

Homologous structures share a similar evolutionary origin but have different functions; analogous structures perform similar functions but have different evolutionary origins.

What are homologous structures?

Anatomical features found in different organisms that share a similar skeletal template and evolutionary origin.

What are analogous structures?

Structural features across different species that perform a similar function but have completely different internal structures.

What is the Linnaean Taxonomic Hierarchy?

A system that classifies organisms into eight progressively specific taxonomic ranks: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

What is binomial nomenclature?

A system that assigns every species a unique two-part scientific name using Latin roots.

What are the rules for writing binomial names?

The genus name is capitalized, the species descriptor is lowercase, and the entire name must be italicized or underlined.

What is a cladogram?

An evolutionary branching diagram that maps out how species are related based on shared, derived characteristics.

What do nodes in a cladogram represent?

Speciation events where a single ancestral lineage splits into distinct new species.

What is a dichotomous key?

A practical identification key used to discover the identity of an unknown organism through a series of paired choices.

What is DNA?

Deoxyribonucleic Acid, the molecule that stores the heritable genetic blueprints of life.

Describe the structure of DNA.

DNA consists of two long strands of nucleotide monomers twisted into a double helix.

What are the nitrogenous bases in DNA?

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

What is the role of mutations in evolution?

Mutations introduce new alleles into a population, creating variations that natural selection acts upon.

What is Lamarckism?

The theory that individuals can acquire traits during their lifetime and pass them to offspring, which is incorrect.

What is Darwinian natural selection?

The theory that evolution occurs at the population level over generations, with individuals possessing advantageous traits surviving and reproducing.

What are the five agents of evolutionary change?

Mutation, Genetic Drift, Founder Effect, Bottleneck Effect, Gene Flow, Non-Random Mating, and Natural Selection.

What is mutation in the context of evolution?

Spontaneous, random changes in the DNA sequence; the only source of entirely new alleles.

How does genetic drift affect small populations?

It causes random changes in allele frequencies, which can lead to the loss of rare alleles.

What is the Founder Effect?

Occurs when a small group breaks away from a large population to colonize a new area, carrying a random sample of the original gene pool.

What is the Bottleneck Effect?

A severe environmental event drastically reduces a population, leading to a narrow gene pool and low genetic diversity.

What is gene flow?

The movement of alleles into or out of a population due to migration of fertile individuals.

What is non-random mating?

When individuals select mates based on specific traits rather than randomly, influencing evolutionary adaptations.

What is natural selection?

The differential survival and reproduction of individuals due to phenotypic differences, leading to adaptation.

What is stabilizing selection?

Favors intermediate phenotypes and selects against extreme variations, narrowing the population curve.

What is directional selection?

Favors phenotypes at one extreme, shifting the population curve in that direction over time.

What is disruptive selection?

Favors extreme phenotypes at both ends and selects against intermediate phenotypes, splitting the population curve.

What is microevolution?

Small-scale changes in allele frequencies within a single population over a short period.

What is macroevolution?

Large-scale evolutionary changes resulting in the origin of new species or higher taxonomic groups over long periods.

What is speciation?

The formation of a new species from a pre-existing ancestral lineage due to reproductive isolation.

What is allopatric speciation?

Speciation that occurs when a population is physically separated by a geographic barrier.

What is sympatric speciation?

The emergence of a new species within the same geographic area without physical barriers.

What are pre-zygotic barriers?

Barriers that prevent fertilization from occurring, such as behavioral, temporal, and mechanical isolation.

What are post-zygotic barriers?

Barriers that occur after fertilization, preventing viable offspring, such as hybrid inviability and hybrid sterility.