BIO106: Exam 2 Review

Anther

produces pollen

Flower

Reproductive organ of angiosperms; produces seeds and facilitates fertilization.

Fruit

Ripened ovary that contains seeds, aids in seed dispersal.

Petal

Brightly coloured modified leaves. Attracts pollinators.

Carpel

Female reproductive organs of a plant.

Pollen

Dust like grains needed for reproduction; carries haploid to female ovule.

Stamen

Male reproductive organ, produces pollen grains; consists of filament (stalk) and anther.

Pollination

Sexual reproduction in flowering plants. The transfer of pollen grains to stigma (male to female structures).

Cotyledon

Stored food for a developing seedling. Monocot and dicot.

Embryo

Early developmental stage of a plant; from fertilization to seed maturity.

Three ways plants can be pollinated

Sexual reproduction (angiosperms and gymnosperms - pollination and seeds), Vegetative (asexual) reproduction (tubers: potatoes), Spore formation (bryophytes and seedless vascular - release haploid spores).

Ways seeds be be dispersed

Wind, water, animals (ingestion or attachment), gravity, ballistic (explosion).

Jean-Baptiste de Lamark

Suggested species evolve through inheritance of acquired characteristics. He proposed that organisms change in response to environmental needs, and traits developed during their lifetime are passed to offspring.

Charles Lyell

Argued that Earth was shaped by slow natural processes, Earth is millions of years old.

Thomas Malthus

Claimed that human population is increasing faster than food supplies.

Alfred Russell Wallace

Independently conceived the theory of natural selection.

Decent with modification

Species evolve over generations by passing traits to offspring; gradual evolution.

Natural selection

Favourable alleles increase in frequency, improving population survival.

Genetic drift

Random fluctuations in allele frequencies, especially in small populations.

Gene flow

Introduction of different alleles between populations, altering frequencies.

Mutation

Introduces new alleles into a population.

Bottleneck effect

Drastic shrinking of population, genes of majority make up most of new population.

Founder effect

Traits of small migrated group being passed down.

Intrasexual

Male competition

Intersexual

Female choice

Adaptive evolution

Phenotypic variation for individuals better suited to their environment. Disruptive, stabilizing, directional.

Directional adaptive evolution

Favours one extreme phenotype. Single allele is favoured due to environmental pressure

Disruptive adaptive evolution

Alleles for both extreme phenotypes are favoured. Can potentially form two groups, causing sympatric selection.

Stabilizing selection

Favours average phenotypes. Increased fitness for the average individual.

Non-random mating

If the animal chooses to mate with like-individuals.

Homozygous alleles

Pair of two of the same alleles for the same gene.

Heterozygous alleles

Pair of two different alleles for the same gene.

Ovule

Female reproductive organ, turns into the seed.

Central cell

Develops into endosperm, when 1n joins with central cell to form 3n.

Seed germination initiation

Imbibition (water uptake) causes seed expansion and ruptures the seed coat.

Gibberellins (GA)

Hormone responsible for elongation and germination.

Abscisic acid (ABA)

Promotes seed dormancy until conditions are optimal.

Charophytes

Algae: closest living relative to algal-like ancestors. unicellular,

How long ago did plants colonize land?

475 million years ago.

Bryophytes

Non-vascular land plants (includes mosses, liverworts, and hornworts). Lacks true roots, stems, and leaves. Dominant gametophyte (haploid), requires water for sperm to swim to eggs.

Seedless vascular plants

Vascular land plants (includes ferns, horsetails [monilophytes], club mosses [lycophytes]). Possess vascular tissue. Dominant sporophyte (diploid).

Gymnosperms

Produces ‘naked’ seeds typically in cones and not fruits. Include conifers, cycads, and ginkgo.

Angiosperm

Flowering/fruit-bearing plants that require pollination to reproduce.

How do Fungi get food?

Heterotrophs, they may secrete digestive enzymes. Decomposers, parasites, and/or symbionts.

What is the dominant life stage for fungi?

Haploid (1n). Dikaryotic (n+n) mycelium.

Lichens

Symbiotic relation between photosynthetic partner and fungus.

Monophyletic

Legitimate clade.

Common ancestor and all descendants.

Paraphyletic

Illegitimate clade.

Common ancestor but not all descendants.

Polyphyletic

Illegitimate clade.

Excludes ancestor with a combination of taxa.

List the classification order of organisms.

Domain, kingdom, phylum, class, order, family, genus, species.

Sister taxa

Closest relative in given tree.

Homologies

Similar physical structures inherited from common ancestor.

Convergent evolution

Similar features, but independent evolution due to ecological pressures.

Does evolution occur in an organism’s lifetime?

No. Evolution occurs over generations.

What is most important to the concept of “Species”?

Reproductive isolation.

Speciation

Ancestral species becomes subdivided by reproductive isolation.

Prezygotic reproductive barriers

Habitat isolation, temporal isolation, behavioural isolation, mechanical isolation, gametic isolation.

Postzygotic reproductive barriers

Reduces hybrid viability. reduced hybrid fertility, hybrid breakdown.

Habitat isolation

Different species inhabit different habitats in same area (eg. terrestrial vs. aquatic).

Prezygotic barrier.

Temporal isolation

Different species inhabit same area but breed at different times (eg. day vs. night).

Prezygotic barrier.

Behavioural isolation

Different species inhabit same area but have unique courtship rituals (eg. different dance styles in birds).

Prezygotic barrier.

Mechanical isolation

Morphological differences prevent successful mating (eg. sperm never reaches egg).

Prezygotic barrier.

Gametic isolation

Sperm of one species unable to fertilize eggs of another.

Prezygotic barrier.

Reduced Hybrid Viability

Hybrid offspring may be frail and underdeveloped.

Postzygotic barrier.

Reduced Hybrid Fertility

Hybrids may be sterile.

Postzygotic barrier.

Hybrid Breakdown

The first generation may reproduce, but the next generation is frail or sterile.

Postzygotic barrier.

Allopatric Speciation

Population is divided into multiple geographically isolated subpopulations and undergo different evolutionary change.

Sympatric Speciation

Reduced geneflow: habitat differentiation, sexual selection, polyploidy.

Polyploidy

More copies of chromosomes than parents. Errors during cell division.

Cannot reproduce with parents’ lineage.

Hybrid Zones

Zones where allopatric populations come into contact again and produce hybrid offspring.

Reinforcement outcome of Hybrid Zone

Reinforcement of reproductive barriers. Hybrids become more and more rare.

Fusion outcome of Hybrid Zone

Reproductive barriers are weak and populations fuse back into a single species.

Stability outcome of Hybrid Zone

Hybrid zone remains stable.

Double fertilization

2 sperm cells.

One fertilizes egg to make zygote.

One combines with polar nuclei to form 3n which turns into endosperm.

Artificial Selection

Humans direct what traits are favourable to create specific variations of organisms.