Grade 11 Study Notes - Cycle Test Preparation

Flashcards to aid in reviewing key concepts and definitions from the study notes for the Grade 11 cycle test.

What is continental drift?

The movement of large masses of land over millions of years.

Who is a palaeontologist?

A scientist who studies ancient life forms through fossils.

What are stromatolites?

Masses of fossilized bacteria.

Define Pangaea.

A super-continent that united almost all of the Earth's continental crust into one landmass surrounded by the Panthalassa ocean.

What is relative dating?

A method that gives an approximate age of a fossil by estimating its age in relation to other rocks and fossils.

Explain radiometric dating.

A direct dating method used if a fossil is found in an area surrounded by radioactive elements to calculate the fossil's age.

What are tree rings used for in dendrochronology?

To compare patterns of wide and narrow tree rings to determine age.

What major event occurred during the Cambrian period?

The Cambrian explosion, resulting in an increase in biodiversity as evidenced in the fossil record.

What was the End-Permian mass extinction?

The worst mass extinction where most marine species were lost, likely caused by volcanic eruptions leading to global warming and ocean acidification.

Describe the fossilization process.

The process where an organism becomes trapped between layers of sand and preserved through sedimentation.

What are the two types of fossils?

Body fossils and trace fossils.

What are coelacanths known for?

Being the oldest living vertebrate known as 'living fossils' that have persisted with little evolutionary change.

What is the evidence for evolution gathered from comparative anatomy?

Homologous structures indicate a common ancestor, while analogous structures provide evidence of convergent evolution.

What is the significance of the fossil evidence for marine fossils compared to terrestrial fossils?

Marine fossils are more complete due to rapid burial, low oxygen conditions, continuous sedimentation, hard parts being common, and less physical disturbance.

What is continental drift?

The movement of large masses of land over millions of years.

Who is a palaeontologist?

A scientist who studies ancient life forms through fossils.

What are stromatolites?

Masses of fossilized bacteria.

Define Pangaea.

A super-continent that united almost all of the Earth's continental crust into one landmass surrounded by the Panthalassa ocean.

What is relative dating?

A method that gives an approximate age of a fossil by estimating its age in relation to other rocks and fossils.

Explain radiometric dating.

A direct dating method used if a fossil is found in an area surrounded by radioactive elements to calculate the fossil's age.

What are tree rings used for in dendrochronology?

To compare patterns of wide and narrow tree rings to determine age.

What major event occurred during the Cambrian period?

The Cambrian explosion, resulting in an increase in biodiversity as evidenced in the fossil record.

What was the End-Permian mass extinction?

The worst mass extinction where most marine species were lost, likely caused by volcanic eruptions leading to global warming and ocean acidification.

Describe the fossilization process.

The process where an organism becomes trapped between layers of sand and preserved through sedimentation.

What are the two types of fossils?

Body fossils and trace fossils.

What are coelacanths known for?

Being the oldest living vertebrate known as 'living fossils' that have persisted with little evolutionary change.

What is the evidence for evolution gathered from comparative anatomy?

Homologous structures indicate a common ancestor, while analogous structures provide evidence of convergent evolution.

What is the significance of the fossil evidence for marine fossils compared to terrestrial fossils?

Marine fossils are more complete due to rapid burial, low oxygen conditions, continuous sedimentation, hard parts being common, and less physical disturbance.

What are Gondwana and Laurasia?

The two smaller super-continents that Pangaea broke into; Gondwana was the southern landmass and Laurasia was the northern landmass.

Define the Law of Superposition.

A principle of relative dating stating that in an undisturbed sequence of rocks, the oldest layers are at the bottom.

What are index fossils?

Fossils of organisms that lived for a short period of time but were widely distributed, used to identify or date the rock layer in which they are found.

What is a half-life?

The time taken for 50\% of the radioactive isotopes in a sample to decay into a stable form.

Define vestigial structures.

Anatomical features that no longer seem to have a purpose in the current form of an organism but were functional in its ancestors.

What is biogeography?

The study of the geographic distribution of plants and animals, which provides evidence for how continental drift influenced evolution.

What are homologous structures?

Organs or skeletal elements of animals and organisms that, by virtue of their similarity, suggest their connection to a common ancestor.

What are analogous structures?

Features in different species that have similar functions but internal structures that are different because they evolved independently, usually as adaptations to similar environments.

Define convergent evolution.

The independent evolution of similar features in species of different lineages, resulting in analogous structures.

What are trace fossils?

Fossils that provide evidence of the activities of ancient organisms, such as footprints, burrows, and coprolites (fossilized droppings).

Why are hard parts (like bones or shells) significant in fossilization?

They are more likely to be preserved than soft tissues because they decay much slower and are more resistant to physical damage.

What is the Panthalassa ocean?

The vast global ancestral ocean that surrounded the super-continent Pangaea during the late Paleozoic and early Mesozoic eras.

What is a mass extinction?

A widespread and rapid decrease in the biodiversity on Earth, where a large percentage of species go extinct in a relatively short geological time frame.

What are transitional fossils?

Fossils that show an intermediate state between an ancestral form and its descendants, providing evidence for evolutionary transitions.

How does biogeography support the theory of evolution?

It shows that species in different regions evolved from common ancestors while landmasses were joined and then diverged as they became isolated by continental drift.

What is the difference between relative and absolute dating?

Relative dating

What is the difference between relative and absolute dating?

Relative dating determines the chronological order of events or fossils (older vs. younger) based on their position in rock layers, whereas absolute dating provides a specific numerical age in years using techniques like radiometric dating.

What is the significance of sedimentary rock in palaeontology?

It is the primary rock type where fossils are preserved because it forms at temperatures and pressures that are low enough to protect organic remains from being destroyed.

How does the fossil record provide evidence for evolution?

It documents the progression of life from simple to complex organisms over time and includes transitional fossils that show the intermediate stages between different species.

What specific environmental changes caused the End-Permian mass extinction?

Massive volcanic eruptions released large amounts of CO_{2}, leading to intense global warming, ocean acidification, and a lack of oxygen (hypoxia) in marine environments.

What are coprolites and what do they reveal?

Coprolites are fossilized animal droppings (a type of trace fossil) that provide scientists with direct evidence of the diet and digestive processes of ancient life forms.

Why is the Law of Superposition essential for relative dating?

It establishes that in any undisturbed sequence of rocks, each layer is older than the one above it, allowing researchers to determine the relative sequence of fossilized organisms.

Which modern landmasses originated from the super-continent Gondwana?

Gondwana eventually broke apart to form South America, Africa, Antarctica, India, and Australia.

Define the term 'living fossil'.

An informal term used for extant species that appear very similar to their fossilized ancestors and have undergone minimal evolutionary change over millions of years (e.g., the coelacanth).

What are the requirements for an organism to become an index fossil?

The organism must have been geographically widespread, easy to identify, and must have existed for a relatively short period of geological time.

Explain the role of radioactive isotopes in dating.

Radioactive isotopes are unstable atoms that decay into stable forms at a constant, known rate; by measuring the ratio of parent to daughter isotopes, scientists can calculate the absolute age of a sample.