BIO1022 On Campus Test 1 Practice Questions - Vocabulary Flashcards

Vocabulary flashcards covering core terms from Weeks 1–6 practice questions in BIO1022.

Natural selection

The process by which heritable variation that increases survival and reproduction becomes more common in a population over generations, driven by environmental pressures.

Heritable variation

Differences in traits among individuals that can be passed to offspring through genes.

Overproduction of offspring

Producing more offspring than can survive, leading to competition for resources.

Artificial selection

The deliberate breeding of organisms by humans to promote desired traits.

Biological species concept

A group of interbreeding populations that produce viable, fertile offspring and are reproductively isolated from other such groups.

Prezygotic reproductive isolation

Barriers that prevent mating or fertilization before a zygote forms (e.g., habitat, temporal, behavioral, mechanical, gametic isolation).

Postzygotic reproductive isolation

Barriers that occur after fertilization, resulting in nonviable or sterile offspring.

Habitat isolation

A prezygotic barrier where populations occupy different habitats and rarely meet to mate.

Hybrid inviability

A postzygotic barrier where hybrid offspring fail to develop or survive.

Reduced hybrid fertility

Hybrid offspring survive but are sterile or have reduced fertility.

Reproductive isolation

Any mechanism that prevents gene flow between populations, maintaining species boundaries.

Allopatric speciation

Speciation caused by geographic separation of populations.

Sympatric speciation

Speciation that occurs within the same geographic area, often via disruptive or sexual selection.

Sexual selection

A form of natural selection where traits that improve mating success are favored.

Speciation

The process by which one species splits into two or more distinct species.

Shared derived character (synapomorphy)

A trait that originated in a common ancestor and is shared by a subgroup, useful for determining relationships.

Shared ancestral character (plesiomorphy)

A trait inherited from an ancestor, found in other groups as well; not diagnostic for a specific clade.

Phylogenetic tree

A diagram showing hypothesized evolutionary relationships among species based on shared characteristics.

Fossils

Preserved remains or traces of organisms used as evidence for evolution and the history of life.

Phylogeny

The evolutionary history and relationships among organisms or groups.

Monophyletic group

A group (also known as a clade) that includes a common evolutionary ancestor and all of its descendants. These groups are considered natural evolutionary units and are used in phylogenetic classification to reflect true evolutionary relationships based on shared derived characters (synapomorphies).

paraphyletic group

A group that includes a common evolutionary ancestor but not all of its descendants. While it shares some common ancestry, it excludes one or more descendant clades, making it an incomplete representation of true evolutionary relationships. This is distinct from a monophyletic group, which includes the common ancestor and all of its descendants, and a polyphyletic group, which includes distant relatives but not their last common ancestor.

polyphyletic group

A group that includes organisms from multiple different evolutionary lineages and excludes their most recent common ancestor. This classification does not accurately represent the true evolutionary history, often leading to misinterpretations of relationships among the included taxa.

Phylogenetic species concept

A species defined by unique genetic/phenotypic traits tracing to a common ancestor.

Morphological species concept

Species defined by morphological similarity and differences.

Ecological (ecological) species concept

Species defined by ecological niche and role in the environment.

Homologous and analogous structures

Homologous Structures

• Definition: Structures in different species that are similar due to descent from a common evolutionary ancestor, but may have evolved to perform different functions.

• Evolutionary Implication: They are evidence of divergent evolution, where related species adapt to different environments over time.

• Examples:

  • The forelimbs of mammals, such as a human arm, a cat's leg, a whale's flipper, and a bat's wing. All share an underlying similar bone structure (humerus, radius, ulna, carpals, metacarpals, phalanges), despite their varied functions (grasping, walking, swimming, flying).

  • The presence of five digits ("pentadactyly") in the limbs of various tetrapods, inherited from a common ancestor.

Analogous Structures

• Definition: Structures in different species that perform similar functions but have evolved independently and do not share a common evolutionary origin.

• Evolutionary Implication: They are evidence of convergent evolution, where unrelated species develop similar traits due to similar environmental pressures or lifestyles.

• Examples:

  • The wings of insects, birds, and bats. All are used for flight, but their underlying structural designs and developmental origins are entirely different. Insect wings are chitinous extensions, bird wings are modified forelimbs with feathers, and bat wings are modified forelimbs with stretched

Amniote egg

An egg with membranes that allow terrestrial reproduction by supplying a protected aquatic environment for development.

synapomorphy

A shared derived trait that is used to determine evolutionary relationships among species.

convergent vs divergent

Convergent evolution refers to the process where unrelated species independently develop similar traits due to similar environmental pressures, while divergent evolution involves related species accumulating differences over time as they adapt to different environments.

Jawed Chordata

Chordates that possess jaws, enabling diverse feeding strategies and active predation.

Notochord

A flexible supportive rod found in chordates along the body axis.

multiregional hypothesis

The multiregional hypothesis is a model of human evolution suggesting that modern humans evolved simultaneously in different regions of the world from earlier hominins, with gene flow between populations.

out of Africa hypothesis

The out of Africa hypothesis is a model of human evolution proposing that modern humans originated in Africa and then migrated to other parts of the world, replacing local populations of earlier hominins.

mtDNA (Mitochondrial DNA)

Mitochondrial DNA (mtDNA) is a small, circular chromosome found in mitochondria, primarily inherited maternally (from mother to offspring). It lacks recombination and has a relatively high mutation rate, making it a valuable tool for tracing maternal lineages, studying human migration, and understanding evolutionary relationships.

Dorsal hollow nerve cord

A hollow nerve cord located dorsally, characteristic of chordates.

Pharyngeal slits

Opening(s) in the throat region used for feeding or gas exchange in chordates.

Post-anal tail

A tail extending beyond the anus at some life stage in chordates.

Coelom

A fluid-filled body cavity completely lined by mesoderm.

Bilaterians

Animals with bilateral symmetry, three germ layers, and typically a coelom.

1. Bilateral Symmetry: Their body plan can be divided into two mirror-image halves along a central axis. This allows for specialized anterior (head) and posterior (tail) ends, as well as distinct dorsal (back) and ventral (belly) surfaces. This body plan is often associated with active locomotion and cephalization (the development of a head region with sense organs).

Three germ layers

These are the primary tissue layers—endoderm, mesoderm, and ectoderm—that form during early embryonic development, specifically during a process called gastrulation. Each layer gives rise to specific tissues and organs:

• Ectoderm: The outermost layer, which develops into the epidermis (skin), nervous system (brain and spinal cord), neural crest cells, and sense organs.

• Mesoderm: The middle layer, forming muscles, bones, connective tissues, the circulatory system, kidneys, and parts of the reproductive system.

• Endoderm: The innermost layer, which gives rise to the lining of the digestive tract, respiratory system, and various glands such as the liver, pancreas, and thyroid.

BLASTULA

An early stage in embryonic development, consisting of a hollow ball of cells formed after fertilization and cleavage. It eventually develops into the gastrula.

Jaw

A hinged structure in vertebrates for biting and processing food; key evolutionary innovation.

Amniotes

Vertebrates with amniotic eggs, enabling terrestrial reproduction (reptiles, birds, mammals).

Tetrapods

Vertebrates that evolved to possess four limbs (or their modified descendants). This group includes amphibians, reptiles, mammals, and birds. Their four limbs are a key adaptation for terrestrial locomotion, originating from lobe-finned fish. Even species like snakes and whales, which lack obvious limbs, are considered tetrapods due to their ancestry.

cnidarians

Aquatic, mostly marine invertebrates (e.g., jellyfish, corals, sea anemones) characterized by:

1. Radial Symmetry: Body parts arranged around a central axis.

2. Diploblastic: Two germ layers (ectoderm and endoderm).

3. Cnidocytes: Specialized stinging cells

diploblastic

Definition: Diploblastic describes animals whose embryos have two primary germ layers: the ectoderm (outer layer) and the endoderm (inner layer). These two layers give rise to all the adult tissues and organs.

• Ectoderm: Develops into the outer covering of the animal and its nervous system.

• Endoderm: Forms the lining of the digestive tract and associated glands.

Between these two layers, diploblastic animals typically have a non-cellular, jelly-like layer called mesoglea, which provides structural support. They lack a true mesoderm, which is the third germ layer found in triploblastic animals (like bilaterians) that gives rise to muscles, bones, and the circulatory system.

Examples of diploblastic animals include Cnidarians (such as jellyfish, corals, and sea anemones) and Ctenophores (comb jellies). Their simpler body plans often exhibit radial symmetry.

triploblastic

Animals with three germ layers, including ectoderm, mesoderm, and endoderm, allowing for more complex structures than diploblastic organisms. Examples include most bilaterians.

Chordata

Phylum that includes animals characterized by four key features present at some stage of their development:

1. Notochord: A flexible, rod-like structure that provides skeletal support, typically found ventral to the neural tube. In vertebrates, it is replaced by the vertebral column during development.

2. Dorsal hollow nerve cord: A unique feature to chordates, this tubular structure develops into the brain and spinal cord in vertebrates.

3. Pharyngeal slits: Openings in the pharynx (throat) that can filter food particles in invertebrate chordates or develop into gills or

Gills

Respiratory organs for gas exchange in aquatic environments.

Lungs

Primary gas-exchange organs in terrestrial vertebrates; exchange air with the bloodstream.

Diffusion

Passive movement of molecules down a concentration gradient; used for simple gas exchange in some animals.

gastrula and gastrulation

The gastrula is a developmental stage in embryogenesis, formed after the blastula, where the process of gastrulation takes place, leading to the formation of germ layers that will develop into various tissues and organs.

Hydrostatic skeleton

A flexible skeletal system found in many invertebrates (like worms, jellyfish, and sea anemones) that provides support and facilitates movement. It is formed by fluid-filled compartments within the body under pressure. Muscle contractions act against this incompressible fluid, changing the shape of the body segments and generating movement, such as peristalsis in worms or jet propulsion in some cephalopods.

Endoskeleton

An endoskeleton is an internal framework of hard, mineralized tissues, primarily composed of bone and/or cartilage, that provides structural support and protection to an organism from within its body. Its key functions include:

1. Support: Provides rigidity, holding the body's shape and counteracting gravity.

2. Protection: Encapsulates and safeguards vital internal organs (e.g., skull protecting the brain, rib cage protecting the heart and lungs).

3. Movement: Serves as attachment points for muscles, allowing for a wide range of locomotion.

4. Blood Cell Production: In many vertebrates, the bone marrow within the endoskeleton is the site of hematopoiesis (the production of blood cells).

5. Mineral Storage: Acts as a reservoir for essential minerals, particularly calcium and phosphorus.

Organisms with endoskeletons, such as vertebrates (fish, amphibians, reptiles, birds, mammals) and some invertebrates (like echinoderms), can grow continuously without needing to shed their outer layer, unlike those with exoskeletons.

Exoskeleton

An exoskeleton is an external, rigid covering that encloses and protects the body of certain invertebrates. It is primarily composed of chitin, a tough polysaccharide, and in some cases, it can be further hardened by minerals like calcium carbonate (e.g., in crustaceans). Key functions include:

1. Protection: Acts as a physical barrier against predators, mechanical damage, and desiccation (water loss).

2. Support: Provides structural support, allowing for terrestrial life and muscle attachment.

3. Locomotion: Serves as an anchor point for muscles, facilitating movement through a system of levers.

4. Sensory Reception: May contain specialized sensory structures (e.g., hairs, antennae) that detect environmental stimuli.

Organisms with exoskeletons, such as arthrop

flow through lung

A flow-through lung is a highly efficient respiratory system found in birds, characterized by a unidirectional airflow. Unlike the tidal breathing in mammals (where air moves in and out of the same pathways), air in a flow-through lung moves continuously in one direction. This is achieved through a complex system of air sacs that act as bellows to push air through the parabronchi, the primary sites of gas exchange.

Key characteristics:

1. Unidirectional Airflow: Air enters through the trachea, passes through the posterior air sacs, moves forward into the lungs (where gas exchange occurs in the parabronchi), and then exits via the anterior air sacs and trachea.

2. Continuous Gas Exchange: Fresh, oxygen-rich air is always moving across the respiratory surfaces (parabronchi), even during exhalation, allowing for more constant and efficient oxygen uptake compared to tidal breathing.

3. High Efficiency: This system ensures that there is always a steep oxygen gradient between the air and the blood, maximizing the amount of oxygen that

Open circulatory system

Circulatory arrangement where blood (hemolymph) bathes organs in body cavities, not always in vessels.

Closed circulatory system

Blood is confined to vessels and pumped by a heart; more efficient transport.

single circulation

A type of circulatory system where blood passes through the heart only once during each complete circuit, typically found in fish. In single circulation, blood travels from the heart to the gills for oxygenation and then to the rest of the body before returning to the heart.

Peristalsis

Wave-like muscle contractions that move contents through the digestive tract.

different chambered hearts

The number of chambers in an animal's heart is a key evolutionary adaptation that reflects its circulatory needs and metabolic demands, particularly related to oxygen transport. The evolution of more complex hearts allows for more efficient separation of oxygenated and deoxygenated blood, supporting higher metabolic rates.

1. Two-Chambered Heart (Fish)

• Structure: Consists of one atrium and one ventricle.

• Circulation: Exhibits single circulation, where blood passes through the heart only once per complete circuit.

• Process: Deoxygenated blood enters the atrium, moves to the ventricle, is pumped to the gills for oxygenation, and then travels directly to the rest of the body before returning to the heart. There is no separation between the systemic and pulmonary circuits.

• Efficiency: Less efficient in delivering oxygen to tissues due to pressure drop in the gills.

2. Three-Chambered Heart (Amphibians and Most Reptiles)

• Structure: Typically has two atria and one ventricle.

• Circulation: Characterized by incomplete double circulation.

• Process:

  • Deoxygenated blood from the body enters the right atrium.

  • Oxygenated blood from the lungs/skin (amphibians) or lungs (reptiles) enters the left atrium.

  • Both atria empty into a single ventricle, leading to some mixing of oxygenated and deoxygenated blood.

  • The ventricle pumps blood to both the lungs (pulmonary circuit) and the body (systemic circuit).

• Adaptation: This partial separation allows for higher blood pressure to systemic tissues than in single circulation, but the mixing in the ventricle reduces the oxygen-carrying capacity of the blood delivered to the body.

3. Four-Chambered Heart (Birds and Mammals)

• Structure: Composed of two atria and two ventricles, completely separated by septa.

• Circulation: Features complete double circulation, with full separation of oxygenated and deoxygenated blood.

• Process:

  • Deoxygenated blood from the body enters the right atrium, then flows to the right ventricle, which pumps it to the lungs (pulmonary circuit).

  • Oxygenated blood from the lungs enters the left atrium, then flows to the left ventricle, which pumps it to the rest of the body (systemic circuit).

• Efficiency: Highly efficient, allowing for high blood pressure to the systemic tissues and ensuring that only oxygenated blood is delivered to the body. This supports the high metabolic rates required for endothermy (warm-bloodedness) and active lifestyles.

Absorption

Uptake of nutrients across the intestinal lining into the bloodstream.

Mechanical digestion

Physical breakdown of food into smaller pieces to increase surface area for enzymes.

Chemical digestion

Enzymatic breakdown of macromolecules into smaller components.

Cecum

The cecum is a blind-ended, pouch-like structure located at the junction of the small and large intestines. Its primary function varies significantly across species:

• In Herbivores: It is often well-developed and plays a crucial role in the digestion of plant material, particularly cellulose. It houses a diverse community of symbiotic bacteria (and other microorganisms) that ferment indigestible carbohydrates (like cellulose) into volatile fatty acids and other nutrients that the host animal can absorb and utilize. Examples include horses, rabbits, and koalas.

• In Omnivores and Carnivores: The cecum is generally smaller and may have a limited or vestigial role in digestion. In humans, for instance, it is a small pouch from which the appendix extends, and its direct digestive function is minimal

Symbiotic bacteria

Bacteria in the digestive system that aid digestion, especially cellulose breakdown.

Monogastric

Animals with a single-chambered stomach (simple stomach).

Ruminant

Herbivores with a multi-chambered stomach for efficient cellulose digestion.

Hormones

Chemical messengers that regulate growth, development, and reproduction.

Environmental sex determination

Sex determined by environmental factors (e.g., temperature) rather than genetics.

Internal fertilization

Fertilization that occurs inside the female body.

External fertilization

Fertilization that occurs outside the body, often in water.

• Common in: Many aquatic invertebrates (e.g., corals, sea urchins), most fish species, and amphibians.

• Advantages:

  • Can result in the production of a large number of offspring.

  • Less parental care is generally required for the actual fertilization process.

• Disadvantages:

  • High predation risk for gametes and developing embryos.

  • Significant waste of gametes due to dispersal and failure to meet.

  • Susceptibility to environmental fluctuations (e.g., water currents, temperature changes, pollution) that can reduce fertilization success.

  • Requires high population density to ensure gamete encounters.

Hermaphrodite

An organism possessing both male and female reproductive organs.

• Self-fertilization: Some hermaphrodites can fertilize their own eggs with their own sperm, though this is often a last resort or occurs in isolated individuals, as it reduces genetic diversity.

• Genetic Diversity: While self-fertilization is possible, cross-fertilization still allows for the benefits of sexual reproduction and genetic recombination.

Sexual reproduction

Reproduction involving fusion of gametes, producing genetically diverse offspring.

Asexual reproduction

Reproduction without gamete fusion, producing genetically identical offspring.

Genetic diversity

Variation in the genetic makeup of individuals within a population.

Satiety

Feeling of fullness after eating; influenced by energy content and fiber.

Fiber (dietary fiber)

Indigestible plant material that adds bulk and promotes fullness and gut health.

Nutritional composition

The makeup of carbohydrates, proteins, fats, vitamins, and minerals in food.