Classification, Evolution, Speciation, and Cladistics TEST

Question 1

Outline the different characteristics of the 3 domains of life.

Answer 1

Archaea - Prokaryotic, single-celled, proteins associated with DNA, cell walls NOT made of peptidoglycan, lives in extreme environments.

Eubacteria - Prokaryotic, single-celled, naked DNA (no proteins), cell walls made of peptidoglycan, bacteria.

Eukarya/Eukaryote - Eukaryotic, single-celled and multicellular, membrane-bound organelles, DNA associated with histone proteins.

Question 2

Know the order of the taxa (in increasing and decreasing size)

Answer 2

(largest to smallest)

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

(King Phillip Came Over For Good Spaghetti)

Question 3

Outline the different characteristics of the 4 plant phyla (and be able to identify plants as belonging to each phylum).

Answer 3

Bryophyta (ex: liverwort and mosses) - 
No vascularization (lacks xylem/phloem), small, reproduces via spores released by stacks, lacking "true" stems, leaves, and roots. 

Filicophyta (ex: ferns) -
Vascularization (has xylem/phloem), reproduces via spores in sporangia.

Coniferophyta (ex: conifers) -
Vascularization (has xylem/phloem), reproduces via naked seeds in cones, narrow leaves with thick, waxy cuticles.

Angiospermophyta (ex: flowering plants) -
Vascularization (has xylem/phloem), reproduce via seeds in fruit, have flowers as reproductive organs.

Question 4

Outline the different characteristics of the 6 phyla of invertebrate animals (and be able to identify invertebrates belonging to each phylum).

Answer 4

Porifera (ex: sponges) - Asymmetrical body plan, no mouth or anus (have pores), may have spicules for structural support.

Annelida (ex: earthworms and leeches) - Bilateral symmetry, separate mouth and anus, body composed of ringed segments.

Cnidaria (ex: jellyfish and anemones) - Radial symmetry, mouth but not anus (single opening), tentacles and stinging cells (cnidocytes).

Mollusca (ex: squids, slugs, snails, bivalves) - Bilateral symmetry, separate mouth and anus, non-visible segments (shell)

Platyhelmintha (ex: flatworms, tapeworms) - Bilateral symmetry, mouth but no anus (single opening), flattened body (increased SA:V ratio).

Arthropoda (ex: insects, spiders, crustaceans) - Bilateral symmetry, separate mouth and anus, have jointed appendages and exoskeleton.

Question 5

Outline the different characteristics of the 5 classes of vertebrate animals (and be able to identify vertebrates belonging to each class).

Answer 5

Reptiles - Covered in scales made of keratin, internal fertilization (lays soft eggs), breathe via lungs, ectothermic.

Fish - Covered in scales (bony plates of skin), reproduce via external fertilization, breathe through gills, ectothermic.

Birds - Covered in feathers made of keratin, internal fertilization (lays hard eggs), breathe via lungs, endothermic.

Amphibians - Moist skin (permeable to gasses), reproduce via external fertilization, breathe through skin, ectothermic.

Mammals - Covered in skin (and keratin hair follicles), have internal fertilization (and lactation), breathe via lungs, endothermic.

Question 6

Be able to define evolution.

Answer 6

The process of cumulative change by means of natural selection over a period of generations.

Question 7

Explain how evolution happens (natural selection).

Answer 7

Evolution happens by means of natural selection. The theory of natural selection, which was proposed by Darwin and Wallace in the mid-1800s, states that there is genetic (inheritable) variation within a population. This variation, in turn, is caused by mutations, meiosis, and sexual reproduction. However, populations of organisms tend to produce more offspring than the environment can support, creating a struggle for survival. Environmental selection pressures give rise to differential rates of reproduction. Individuals with beneficial traits are likely to survive and reproduce, while those less adapted produce less offspring. Over generations, these beneficial traits become more common.

Question 8

Outline the evidence for evolution provided by fossils, selective breeding/ artificial selection, and homologous structures (the pentadactyl limb).

Answer 8

Fossil Record

• The fossil record shows that changes have occurred in organisms and these changes have occurred in a consistent sequence of development (the law of fossil succession) (ex: Ferns always appear before flowering plants).
• Transitional Fossils: Transitional fossils represent intermediary forms within the evolution of a genus and demonstrate species connections (ex: The archaeopteryx links the evolution of birds (wings and feathers) to dinosaurs (jaws and claws)).

Selective Breeding

• Selective breeding involves the mating of animals with the intention of producing desired characteristics for the offspring.
• As human intervention drives selection, changes will occur over fewer generations as phenotypes extremes are promoted.

Homologous Structures:

• The rapid diversification of an anatomical feature is a result of adaptive radiation. Closely related species demonstrate greater homology.
• Ex: The pentadactyl limb is a prime example of a homologous structure, as there are different appendages, yet the bone structure is the same.

Question 9

Compare analogous (convergent evolution) and homologous structures (divergent evolution/ adaptive radiation).

Answer 9

Homologous structures are similar in structure (as they are built with the same basic parts). But they are used for different functions or are used in different ways. Homologous structures develop by adaptive radiation/divergent evolution, in which several new species “rapidly” diversify from a common ancestor in order to fill new niches.

Analogous structures are similar because they serve a common function. But they are different in structure because they derived from different evolutionary paths. These different paths arose from convergent evolutions, which was the need to perform the same function in an environment - exposure to the same selective pressures in the environment leads to the development of similar features with similar functions. But these features came from different lineages.

Question 10

Outline the sources of variation within a population.

Answer 10

Mutation - Factors such as excess radiation creates changes to the gene sequence.

Sexual reproduction - Any one of the gametes from one individual can fertilize anyone of the gametes of another individual.

Gene flow - immigration and emigration.

Question 11

Outline the characteristics that define members of a species.

Answer 11

• They can breed
• Produces fertile offspring
• Similar numbers of chromosomes
• Similar structures

Question 12

Define speciation.

Answer 12

Formation of new species (no longer able to interbreed).