BIO105 Unit 3 Exam Study Guide Flashcards

Comprehensive vocabulary flashcards covering ecological concepts, microbial diversity, animal and plant evolution, and fungal relationships from the BIO105 Unit 3 Study Guide.

Organism

One individual living thing.

Population

Members of the same species living in one area.

Community

Populations of different species interacting in the same area.

Ecosystem

A community of organisms plus its nonliving environment.

Biosphere

All regions of Earth where life exists.

Population density

Number of individuals per unit of area or volume.

Carrying capacity ($K$)

Maximum population an environment can sustainably support.

Density-dependent factors

Factors that have stronger effects as population density increases, such as competition, disease, and predation.

Density-independent factors

Factors that affect populations regardless of population density, such as droughts, fires, and severe storms.

Niche

A species' role in its environment, including its resource use and interactions.

Resource partitioning

A strategy by which species reduce competition by using different resources, locations, or times.

Competitive exclusion

The principle that two species competing for the same limiting resources cannot indefinitely occupy exactly the same niche under the same conditions.

The $10\%$ Rule

The trophic principle that approximately $10\%$ of the energy at one trophic level transfers to the next level, while most is used in life processes or lost as heat.

Species richness

The number of different species present in an area.

Species evenness

How evenly individuals are distributed among species.

Endemic species

Species native to and restricted to a particular geographic area.

Biodiversity hotspot

An area with high concentrations of endemic species that faces substantial habitat loss.

Extinction vortex

A cycle in which a small population loses genetic diversity, experiences reduced reproduction and survival, and becomes even smaller, increasing its risk of extinction.

Microbe

A microscopic organism, often single-celled.

Plasmids

Small DNA molecules separate from the main bacterial chromosome that may carry useful genes.

Binary fission

Asexual reproduction in which a bacterial cell copies its DNA and divides into two cells.

Transformation

The uptake of free DNA from the environment by a bacterial cell.

Transduction

DNA transfer between bacteria mediated by a virus that infects bacteria.

Conjugation

DNA transfer between bacterial cells through direct cell-to-cell contact.

Methanogens

Archaea that produce methane and often live in oxygen-free environments.

Symbiosis

A close, long-term relationship between organisms of different species.

Nitrogen fixation

The process by which certain bacteria convert atmospheric nitrogen into ammonia or related usable forms.

Pathogen

An organism or agent that causes disease.

Adaptive radiation

Diversification of one ancestral lineage into multiple species adapted to different ecological niches.

Cephalization

Concentration of sensory organs and nervous tissue at the head.

Blastula

Early embryonic stage consisting of a ball or layer of cells surrounding a cavity.

Gastrulation

Process that forms the primary germ layers during embryonic development.

Acoelomate

An animal that lacks a fluid-filled body cavity between the digestive tract and body wall.

Pseudocoelomate

An animal having a body cavity that is not completely lined by mesoderm.

Coelomate

An animal that has a true coelom completely lined by mesoderm.

Protostomes

Animals in which the blastopore typically develops into the mouth.

Deuterostomes

Animals in which the blastopore typically develops into the anus.

Amniotic egg

An egg containing membranes that protect the embryo and support development on land, reducing dependence on external water for reproduction.

Sporophyte

The diploid ($2n$) plant stage that produces haploid spores through meiosis.

Gametophyte

The haploid ($n$) plant stage that produces gametes through mitosis.

Bryophytes

Nonvascular plants lacking true vascular tissue where the gametophyte is the dominant generation and sperm generally require water to reach the egg.

Xylem

Vascular tissue that transports water and minerals, primarily from roots upward, and provides structural support.

Phloem

Vascular tissue that transports sugars and other organic substances from sources to sinks.

Double fertilization

An angiosperm process where one sperm fertilizes the egg to form a diploid zygote and another fuses with the central cell to form the typically triploid endosperm.

Hyphae

Threadlike structures that make up the growing bodies of many fungi.

Mycelium

A network of fungal hyphae.

Mycorrhizae

Mutualistic relationships between fungi and plant roots where fungi help absorb water and minerals while plants provide sugars.

Lichens

Symbiotic partnerships between fungi and photosynthetic algae or cyanobacteria.

Homologous structures

Structures that show similarity due to shared evolutionary origin, even if their functions differ.

Analogous structures

Structures that have a similar function or appearance without sharing the same underlying evolutionary origin.

Phototrophs

Use light as an energy source

Chemotrophs

Obtain energy from chemical reactions

Cocci (bacterial shape)

Circle Shape

Bacilli (bacterial shape)

Rod-Shaped

Spirilla (bacterial shape)

Spiral-Shaped

Cell membrane

Controls the movement of substances into and out of cell

Cell Wall

Provies support and protection

Cytoplasm

Fluid environment where cellular reactions occur

Ribsomes

Make proteins

Plasmids

Small DNA molecules separate from the main chromosome; may carry useful genes

Flagella

Structures used for movement in many bacteria

Pili

Structures that help bacteria attach to surfaces or exchange DNA

What makes an animal?

Multicellular, Eukaryotic heterotrophs that lack cell walls

Ectoderm

One of 3 germ layers. Outer later that gives rise to the epidermis and nervous system.

Mesoderm

One of 3 germ layers. The middle layer that forms many muscles, connective tissues, and internal structures.

Endoderm

One of 3 germ layers. The inner layer that forms much of the lining od the digestive tract and associated organs.

Diploblastic

Animals with 2 primary germ layers; outer and inner

Triploblastic

Animals with 3 primary germ layers; all three layers

Invertebrate

No backbone

Porifera

Sponges; lack true tissues and conventional organs; mostly asymmetrical; have specialized cells.

Cnidaria

Jellyfish, Corals, and Hydras; radial symmetry; have two primary germ layers; have stinging cells called cnidoctyes.

Platyhelminthes

Flatworms; bilateral symmetry; triploblastic and acoelomate.

Annelida

Segmented worms; bilateral symmetry segmented bodies; includes earthworms and leeches.

Mollusca

Snails, Clams, and Octopuses; muscular foot, visceral mass, and mantel; may produce a shell.

Arthropoda

Insects, Spiders, and Crustaceans; jointed appendages; chitinous exoskeleton; grow by molting.

Echinodermata

Sea stars and Sea urchins; marine deuterostomes; adults typically have radial symmetry; larvae have bilateral symmetry.

Chordates

have the following features at some point in development: Notochord, Dorsal hollow nerve chord, Pharyngeal slits or pouches, and post-anal tail.

Gymnosperms

Vascular plants the produce seeds; not enclosed in fruits (“naked seeds”).

Angiosperms

Produce flowers and seeds enclosed within fruits.