Bio 120 Exam 3 Study Guide: Microbes, Evolution, and Plants

A set of flashcards covering essential vocabulary terms and concepts from the Bio 120 exam study guide on microbes, evolution, and plants.

Microbe

Any microscopic organism, including bacteria, archaea, viruses, protists, and some fungi.

Viruses

Non-living infectious agents that cannot reproduce on their own and require a host cell to replicate.

Binary fission

The process of bacterial replication where one cell divides into two identical daughter cells.

Pathogen

Any microorganism that causes disease, including certain bacteria, viruses, protists, and fungi.

Antibiotics

Medications that kill or inhibit bacteria but do not work on viruses.

Bacterial energy sources

Methods bacteria use to obtain energy, including photosynthesis, breaking down chemical compounds, and decomposing organic matter.

Natural selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Speciation

The process by which new species arise.

Allopatric speciation

Speciation that occurs when populations are geographically separated.

Sympatric speciation

Speciation occurring within the same geographic area, often due to polyploidy or behavioral isolation.

Xylem

The vascular tissue responsible for transporting water and minerals from roots to leaves.

Phloem

The vascular tissue responsible for transporting sugars throughout the plant.

Stomata

Tiny pores on plant leaves and stems that allow for gas exchange and regulate water loss.

Gametophyte

The haploid (n) generation in plants that produces gametes.

Sporophyte

The diploid (2n) generation in plants that produces spores through meiosis.

Fungi

Multicellular or unicellular organisms that absorb nutrients from their environment and have cell walls made of chitin.

Bryophytes

Nonvascular plants such as mosses that lack xylem and phloem and require moisture for reproduction.

Gymnosperms

Naked seed plants that produce seeds not enclosed in fruit, often found in cones.

Angiosperms

Flowering plants that produce seeds enclosed in fruit and are the most diverse plant group.

Mutations

Random changes in DNA that create new alleles and genetic variation in a population.

Disruptive selection

A type of natural selection that increases the frequency of extreme traits and decreases the frequency of intermediate traits.

Directional selection

A type of natural selection that favors individuals at one extreme of the trait spectrum.

Stabilizing selection

A type of natural selection that favors intermediate traits and reduces the extremes.

Reproductive isolating mechanisms

Mechanisms that prevent different species from interbreeding, including prezygotic and postzygotic barriers.

Gene Flow

The transfer of genetic material from one population to another.

Genetic Drift

Random changes in allele frequencies in a population due to chance, especially prominent in small populations.

Founder Effect

A type of genetic drift that occurs when a new population is established by a very small number of individuals from a larger population.

Bottleneck Effect

A sharp reduction in the size of a population due to environmental events, reducing the genetic diversity of the population.

Sexual Selection

A mode of natural selection where members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to mates.

Homologous Structures

Structures in different species that are similar because of common ancestry.

Cuticle

A protective waxy layer covering the epidermis of leaves and stems, preventing water loss.

Roots

Underground plant organs that anchor the plant and absorb water and dissolved nutrients.

Stems

The main body or stalk of a plant, typically rising above ground but occasionally subterranean, which bears leaves and flowers.

Leaves

The primary photosynthetic organs of most plants, typically broad, flattened, and green.

Alternation of Generations

The life cycle of plants, characterized by two alternating multicellular stages: a haploid gametophyte and a diploid sporophyte.

Meristematic Tissue

Plant tissue consisting of undifferentiated cells that can divide and differentiate into specialized plant tissues.

Analogous Structures

Structures that have similar functions in different species but evolved independently and do not share a common ancestry.

Vestigial Structures

Remnants of organs or structures that were functional in an early ancestor but are no longer useful to the organism.

Hardy-Weinberg Principle

A principle stating that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

Divergent Evolution

The process by which two or more species, sharing a common ancestor, become more and more dissimilar over time.

Convergent Evolution

The process by which unrelated organisms independently evolve similarities when adapting to similar environments.

Coevolution

The process by which two or more species evolve in response to changes in each other.

Pollination

The transfer of pollen from the anther to the stigma in flowering plants, or from the male cone to the female cone in gymnosperms.

Fertilization (Plants)

The fusion of male and female gametes to form a zygote, leading to seed development in plants.

Seed

A plant embryo enclosed in a protective outer covering, formed from the ovule after fertilization.

Fruit

The mature ovary of a flowering plant, enclosing the seed or seeds.

Tropism

A growth response of a plant towards or away from an environmental stimulus.

Phototropism

The growth of a plant in response to light, typically bending towards a light source.

Gravitropism (Geotropism)

The growth of a plant in response to gravity; roots typically show positive gravitropism (grow downwards), and shoots show negative gravitropism (grow upwards).

Thigmotropism

The growth of a plant in response to touch, often seen in climbing plants or tendrils wrapping around supports.

Photoperiodism

The physiological reaction of organisms to the length of day or night, particularly in terms of flowering and dormancy in plants.