Biology Taxonomy, Evolution, and Ecology: Key Concepts and Definitions

What is taxonomy?

The science of classifying and naming living organisms.

Who is Carl Linnaeus?

The father of modern taxonomy who created binomial nomenclature.

What is binomial nomenclature?

A two-part scientific naming system using Genus and species names.

What are the rules for binomial nomenclature?

Genus capitalized, species lowercase, both italicized.

What is the correct format for humans?

Homo sapiens

What does the taxonomy hierarchy mnemonic stand for?

Kingdom, Phylum, Class, Order, Family, Genus, Species.

What is a species?

A group of organisms that can breed and produce fertile offspring.

What is a dichotomous key?

A tool that identifies organisms using paired either/or descriptors.

What is an organism?

A single living individual.

What is a population?

All individuals of the same species in the same area.

What is a community?

All populations of different species living together.

What is an ecosystem?

Living and nonliving components interacting in an area.

What is the biosphere?

All ecosystems on Earth combined.

What are biotic factors?

Living components of an ecosystem.

What are abiotic factors?

Nonliving environmental factors like sunlight, water, and temperature.

What is a producer?

An organism that makes its own food through photosynthesis.

What is a consumer?

An organism that gets energy by eating other organisms.

What is a decomposer?

An organism that breaks down dead matter and recycles nutrients.

What does a food chain/web show?

The flow of energy between organisms.

Which direction do arrows point in a food chain?

In the direction energy travels (prey → predator).

What are trophic levels?

Feeding levels in an ecosystem.

What is the correct trophic order?

Producers → Primary consumers → Secondary consumers → Tertiary consumers.

What is the 10% Rule?

Only about 10% of energy transfers to the next trophic level.

Why is energy lost between trophic levels?

Most energy is lost as heat through metabolism.

Which organisms have the most energy in an energy pyramid?

Producers.

Which organisms have the least energy?

Top predators.

How is CO₂ removed from the atmosphere in the carbon cycle?

Through photosynthesis.

How is CO₂ returned to the atmosphere?

Cellular respiration, decomposition, and combustion.

What is nitrogen fixation?

Bacteria converting N₂ gas into usable nitrogen compounds.

Why is nitrogen fixation important?

Plants cannot use atmospheric nitrogen directly.

What is denitrification?

Bacteria converting nitrates back into N₂ gas.

Which organisms are key in the nitrogen cycle?

Bacteria.

What is natural selection?

Organisms with beneficial traits survive and reproduce more successfully.

What is an adaptation?

A heritable trait that improves fitness.

What is genetic variation?

Differences in DNA among individuals.

What is the main source of genetic variation?

Random mutations.

Why is genetic diversity important?

It increases survival chances during environmental change.

What is coevolution?

Two species influencing each other's evolution.

What is convergent evolution?

Unrelated species evolving similar traits.

What structures result from convergent evolution?

Analogous structures.

What is divergent evolution?

One ancestor splitting into multiple species.

What structures result from divergent evolution?

Homologous structures.

What are homologous structures?

Structures with similar anatomy but different functions.

What do homologous structures indicate?

Common ancestry.

What are analogous structures?

Structures with similar functions but different origins.

What are vestigial structures?

Reduced structures inherited from ancestors.

What does the fossil record show?

Transitional forms and species divergence over time.

What does molecular/DNA evidence show?

Closely related species share more DNA.

What is geographic isolation?

Physical barriers separating populations.

What type of speciation results from geographic isolation?

Allopatric speciation.

What is temporal isolation?

Species breeding at different times.

What is behavioral isolation?

Different mating behaviors preventing reproduction.

What is mechanical isolation?

Structural reproductive differences preventing mating.

What is a gene?

A segment of DNA coding for a protein.

What is an allele?

A different version of a gene.

What is genotype?

The allele combination an organism carries.

What is phenotype?

The observable trait.

What is a dominant allele?

An allele expressed whenever present.

What is a recessive allele?

An allele expressed only when two copies are present.

What does homozygous mean?

Having two identical alleles.

What does heterozygous mean?

Having two different alleles.

What is incomplete dominance?

A blended heterozygous phenotype.

What is codominance?

Both alleles fully expressed.

How do you set up a Punnett square?

One parent across the top, one down the side.

What is the genotypic ratio for Bb × Bb?

1 BB : 2 Bb : 1 bb

What is the phenotypic ratio for Bb × Bb?

3 dominant : 1 recessive

What is DNA?

Double-stranded molecule storing genetic information.

What bases are found in DNA?

A, T, G, C.

What is RNA?

Single-stranded molecule involved in protein synthesis.

What base replaces thymine in RNA?

Uracil (U).

According to Chargaff's rules, what pairs with A?

T in DNA, U in RNA.

What pairs with G?

C.

What is DNA replication?

Semi-conservative copying of DNA.

During replication, each new DNA molecule contains what?

One old strand and one new strand.

What is transcription?

DNA → mRNA.

Where does transcription occur?

In the nucleus.

What is translation?

mRNA → protein.

Where does translation occur?

At ribosomes in the cytoplasm.

What is a codon?

A 3-base mRNA sequence coding for an amino acid.

What is the start codon?

AUG.

What are the stop codons?

UAA, UAG, UGA.

What is a mutation?

A change in DNA sequence.

What is a point mutation?

A substitution of one nucleotide.

What is a silent mutation?

A mutation that does not change the amino acid.

What is a frameshift mutation?

An insertion or deletion that shifts the reading frame.

What is an insertion mutation?

Addition of nucleotides.

What is a deletion mutation?

Removal of nucleotides.

What is a somatic mutation?

A mutation in body cells that is not inherited.

What is a germline mutation?

A mutation in gametes that can be inherited.

What happens during interphase?

Cell growth, DNA replication, and preparation for division.

What is mitosis?

Division producing 2 identical diploid cells.

What is meiosis?

Division producing 4 unique haploid gametes.

What are somatic cells?

Body cells excluding gametes.

What are gametes?

Egg and sperm cells.

What does diploid mean?

Two sets of chromosomes (2n).

What does haploid mean?

One set of chromosomes (n).

What is the purpose of mitosis?

Growth and repair.

What is the purpose of meiosis?

Sexual reproduction.

Are daughter cells from mitosis identical or unique?

Identical.

Are daughter cells from meiosis identical or unique?

Unique.