Biology Exam Review: Patterns of Evolution, Evolutionary Mechanisms, and Homeostasis

Flashcards reviewing key concepts of patterns of evolution, mechanisms of evolutionary change, and human homeostasis.

What is divergent evolution?

The evolutionary process in which one ancestral species gives rise to different species in response to different environments.

How do woolly mammoths and elephants illustrate divergent evolution?

Mammoths developed thick fur and small ears adapted for cold climates, whereas elephants developed large ears and little hair for warm environments.

How do the forelimbs of humans, bats, whales, and cats demonstrate divergent evolution?

They originated from a common ancestral limb structure but evolved for distinct functions such as grasping, flying, swimming, or running.

What is convergent evolution?

The evolutionary process in which unrelated species independently evolve similar traits due to similar environmental pressures.

How do sharks and dolphins demonstrate convergent evolution?

Sharks (fish) and dolphins (mammals) independently evolved streamlined body shapes and fins for swimming despite descending from very different ancestors.

Why did the thylacine evolve a similar appearance to the wolf?

Because both species evolved independently as predators under similar lifestyles and ecological pressures, illustrating convergent evolution.

What adaptations did hummingbirds and hawk moths independently evolve for feeding?

They both evolved long feeding structures to drink nectar while hovering near flowers.

What is adaptive radiation?

The process in which a single ancestor species rapidly diversifies into multiple new species to fill different ecological niches.

How many finch species evolved from a single ancestral bird in the Galápagos Islands?

Approximately $15\text{--}18$ finch species.

What key trait adapted among Hawaiian honeycreepers as they diversified into different ecological niches?

Beak shapes, which adapted for specialized feeding on nectar, insects, or seeds.

What is coevolution?

An evolutionary pattern where two or more species mutually influence each other's evolution.

Describe the coevolutionary relationship between the yucca moth and the yucca plant.

The yucca moth pollinates the yucca plant while laying its eggs inside the flower; its larvae feed on some seeds, while the plant successfully reproduces through the moth's pollination.

What are the six primary mechanisms of evolutionary change?

Natural selection, artificial selection, genetic drift, gene flow, mutation, and recombination.

What is natural selection?

The process where organisms with traits better suited to their environment survive and reproduce more successfully than others.

How did peppered moth populations in England change during the Industrial Revolution?

Dark-colored moths survived predation better than light-colored moths, causing the population to become predominantly dark-colored over time.

What is artificial selection?

The process where humans intentionally breed individuals with desired traits, also known as selective breeding.

Which ancestral wild plant species gave rise to cabbage, Brussels sprouts, kohlrabi, kale, broccoli, and cauliflower through artificial selection?

Brassica oleracea.

What wild grass was selectively bred by humans over generations to create modern corn?

Teosinte.

What is genetic drift?

A random change in allele frequencies in a population, which can lead to the loss or fixation of alleles over time.

What is the bottleneck effect?

A drastic reduction in population size due to a catastrophe, resulting in a surviving population with significantly reduced genetic variation.

Why do wild cheetah populations suffer from low genetic diversity and high disease susceptibility?

Because they went through a severe population bottleneck over $10{,}000$ years ago due to climate change and human pressures.

What is the founder effect?

An event occurring when a few individuals colonize a new habitat, forming a new population with allele frequencies different from the original population.

Why do Amish communities exhibit higher rates of rare genetic disorders like Ellis-van Creveld syndrome?

Because they were established by a small number of founding settlers with limited founding genes and practice isolated breeding.

What is gene flow?

The migration of individuals from one population to another followed by interbreeding, introducing new alleles into the host population.

What is a main limitation or side effect of high gene flow between two populations?

It reduces genetic differences between populations, making them more genetically similar and potentially preventing them from becoming distinct species.

What is a mutation in biological evolution?

A random change in DNA sequences, serving as the ultimate source of all genetic variation.

How did mutation lead to trichromatic color vision in primates?

A gene duplication followed by a mutation created a third light receptor sensitive to red light.

What is genetic recombination?

The shuffling of genes during sexual reproduction (such as crossing over during Prophase I) that creates new combinations of alleles in offspring.

What is homeostasis?

The process by which the human body maintains a stable internal environment despite constant external changes.

What is dynamic equilibrium in homeostatic regulation?

A state in which internal conditions continuously fluctuate within a narrow, safe range, but corrective mechanisms quickly restore balance.

How does negative feedback maintain homeostatic balance?

By detecting a change in conditions and producing responses that reverse that change to bring conditions back to normal.

What are the four major components involved in every homeostatic control mechanism?

Stimulus, Receptor, Control Center, and Effector.

What is the normal set point for human body temperature?

Approximately $37\,^\circ\text{C}$.

Which brain structure serves as the body's control center and thermostat for temperature regulation?

The hypothalamus.

What cooling responses does the body initiate when body temperature becomes too high?

Sweat glands produce sweat for evaporative cooling, and blood vessels near the skin widen through vasodilation to release heat.

What warming responses does the body initiate when exposed to cold environments?

Blood vessels near the skin narrow through vasoconstriction, muscles rapidly contract to cause shivering, and metabolism increases.

What condition can occur if body temperature rises above $40\,^\circ\text{C}$?

Heat stroke.

Which hormone is released by the pancreas when blood glucose levels increase after eating?

Insulin.

In what form is excess blood glucose stored in the liver and muscles?

Glycogen.

Which hormone is secreted by the pancreas when blood glucose drops hours after a meal?

Glucagon.

What is the key physiological difference between Type 1 and Type 2 diabetes mellitus?

In Type 1 diabetes, the pancreas produces little or no insulin; in Type 2 diabetes, body cells become less responsive to insulin.

What is considered a normal adult blood pressure reading?

Approximately $120/80\,\text{mmHg}$.

What do systolic and diastolic blood pressure numbers measure?

Systolic measures pressure during heart contraction, while diastolic measures pressure while the heart relaxes between beats.