Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The Fossil Record: Fossils provide a chronological sequence of organisms throughout history. This sequence matches the complexity expected from evolution, with simpler organisms like appearing before . Transitional fossils, such as , show the link between fish and amphibians.
Selective Breeding: Artificial selection provides evidence that significant phenotypic changes can occur within a species over relatively short periods. By breeding individuals with desired traits, humans have drastically altered the morphology of domesticated animals and crops.
Homologous Structures: These are anatomical features that are similar in structure but may perform different functions. The pentadactyl limb (found in mammals, birds, amphibians, and reptiles) is a classic example. This indicates a common ancestry and the process of adaptive radiation.
Speciation and Clines: Populations of a species can gradually diverge into separate species by evolution. Continuous variation across a geographical range (clines) supports the idea that species are not fixed and can undergo gradual divergence.
Industrial Melanism: Observable evolution occurs in response to environmental changes. The peppered moth () shifted from a light-colored population to a dark-colored (melanic) population due to soot-covered trees during the Industrial Revolution, demonstrating natural selection.
Vestigial Structures: Some organisms possess reduced or non-functional structures (e.g., the pelvic bone in whales) that were functional in their ancestors, providing evidence of evolutionary history.
📐Formulae
💡Examples
Problem 1:
Calculate the approximate age of a fossil if the remaining amount of is of its original value. Assume the half-life () of is years.
Solution:
is equivalent to of the original sample. This represents three half-lives (). Total Age .
Explanation:
Radioactive dating uses the decay of isotopes to estimate the age of organic matter in the fossil record. By measuring the ratio of stable isotopes to unstable isotopes like , scientists can determine when an organism died.
Problem 2:
Describe how the pentadactyl limb provides evidence for evolution.
Solution:
The pentadactyl limb consists of a single proximal bone (humerus/femur), two distal bones (radius/ulna or tibia/fibula), a group of wrist/ankle bones (carpals/tarsals), and five digits (metacarpals/phalanges). Despite having different functions like flying (bats), swimming (whales), or running (horses), the fundamental bone structure is the same.
Explanation:
This structure is a 'homologous structure'. The similarity in anatomy suggests that these diverse organisms evolved from a common ancestor through 'adaptive radiation', where the basic structure was modified to suit different environmental niches.