PRELIMINARY STAGE 2024
Contest 28
St. John’s Grammar School: 38 points (Winner)
Accra High School: 32 points
St. Francis Girls’ SHS: 13 points
Contest 29
Kumasi Academy: 56 points (Winner)
Saviour SHS: 16 points
Battor SHS: 14 points
Contest 30
Ghana SHS, Koforidua: 49 points (Winner)
Sefwi Wiawso SHS: 15 points
Northern School of Business: 09 points
ROUND 4 - TRUE OR FALSE
FIRST SET OF QUESTIONS
1. Fossil dates provide important information about the age of fossils and the geological time scale.
ANSWER: TRUE
EXPLANATION:
Fossil dating allows scientists to place fossils within the geological time scale and understand the sequence of events in Earth's history.
2. Fossil dates are often not very precise because the dating methods used to determine their age have limitations and uncertainties.
ANSWER: TRUE
EXPLANATION:
Methods like radiometric dating and relative dating have inherent uncertainties, so fossil ages are often approximate rather than exact.
3. Fossil dates cannot provide valuable insights into the past, so they should be interpreted with caution and considered within the context of other geological and paleontological evidence.
ANSWER: FALSE
EXPLANATION:
Fossil dates are valuable for understanding Earth's history, but they must be interpreted alongside other evidence to form accurate conclusions.
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PRACTICE QUESTIONS
1. QUESTION: Radiometric dating gives an age in years, while relative dating only places fossils in order of age.
ANSWER: TRUE
EXPLANATION:
Radiometric (absolute) dating uses the known half-life of an isotope.
Relative dating only says which fossil or layer is older.
2. QUESTION: In undisturbed sedimentary rock layers, the deepest layers are usually the youngest.
ANSWER: FALSE
EXPLANATION:
By the law of superposition, lower layers were laid down first, so they are the oldest.
3. QUESTION: Index fossils are useful because they come from species that lived for a short time but over a wide area.
ANSWER: TRUE
EXPLANATION:
Such fossils mark a narrow time range, so rock layers containing them in different places can be matched.
4. QUESTION: Fossils in sedimentary rock are usually dated directly by radiometric dating of the sediment grains around them.
ANSWER: FALSE
EXPLANATION:
The grains came from older rocks, so their radiometric ages are not the age of the fossil.
Volcanic layers above and below the fossil are dated instead to bracket its age.
5. QUESTION: A fossil lying between two dated volcanic ash layers must be younger than the lower layer and older than the upper layer.
ANSWER: TRUE
EXPLANATION:
The lower ash was laid down before the fossil and the upper ash after it.
6. QUESTION: The geological time scale divides Earth's history into eons, eras, periods and epochs.
ANSWER: TRUE
EXPLANATION:
These are the standard divisions, from the longest to the shortest.
7. QUESTION: The half-life of an isotope used for dating changes as the rock gets older.
ANSWER: FALSE
EXPLANATION:
A half-life is a constant of the nuclide; it does not depend on the age or amount of the sample.
8. QUESTION: Uranium–lead dating is suitable for rocks that are billions of years old.
ANSWER: TRUE
EXPLANATION:
Uranium-238 has a half-life of about 4.5 billion years, comparable to the ages of the oldest rocks.
9. QUESTION: A radiometric age is usually quoted together with an uncertainty.
ANSWER: TRUE
EXPLANATION:
Measurement errors and assumptions about the sample limit the precision of the age.