ONE-EIGHTH STAGE 2025
Ghana National College: 65 points
Tema Secondary School: 33 points
Effiduase SHCS: 28 points
Mankranso SHS: 43 points
St Paul's SHS, Denu: 23 points
Adonten SHS: 14 points
St. Thomas Aquinas SHS: 51 points
Tamale SHS: 37 points
O'Reilly SHS: 25 points
ROUND 5 - RIDDLE
RIDDLE
I am a phenomenon in evolutionary biology.
My name is derived from a Latin word which means a great great great grandfather or more generally an ancestor.
I have been observed in humans such as with infants born with vestigial tails.
I can also been seen in humans who possess large teeth like those of other primates.
I am a phenomenon in which a phenotypic trait reappears in an organism after disappearing for several generations.
Who am I?
ANSWER: Atavism
EXPLANATION:
Atavism (Latin atavus, ancestor) is the reappearance of an ancestral trait after it has been absent for several generations.
Examples include human babies born with a tail-like appendage and whales born with hind limbs; dormant ancestral genes are thought to be switched on again.
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PRACTICE QUESTIONS
1. RIDDLE:
I am a feature of living things.
I am present in every member of a species, not just a few.
I am reduced in size.
I have lost most or all of my original function.
I am a remnant of a working organ in the ancestors.
The human appendix and coccyx are examples of me.
Who am I?
ANSWER: VESTIGIAL STRUCTURE
EXPLANATION:
A vestigial structure is a permanent, reduced remnant, unlike an atavism, which reappears only now and then.
2. RIDDLE:
I am a phenomenon in populations.
I involve a single species.
In me, two or more distinct forms live together in one population.
I can be kept stable by natural selection.
Human ABO blood groups show me.
My name means "many forms".
Who am I?
ANSWER: POLYMORPHISM
EXPLANATION:
Polymorphism is the existence of two or more distinct forms in one population.
3. RIDDLE:
I am a mechanism of evolution.
I change allele frequencies.
I act by chance, not by selection.
I have the strongest effect in small populations.
I can lead to an allele being lost or fixed.
I am the random change of allele frequencies from one generation to the next.
Who am I?
ANSWER: GENETIC DRIFT
EXPLANATION:
Genetic drift is random change in allele frequencies, strongest in small populations.
4. RIDDLE:
I am a condition in humans.
I can be present from birth or appear later.
I affect the body's covering.
I can cover the face and body.
I am sometimes described as an atavism.
I am excessive hair growth, once called "werewolf syndrome".
Who am I?
ANSWER: HYPERTRICHOSIS
EXPLANATION:
Hypertrichosis is excessive hair growth, sometimes regarded as an atavism.
5. RIDDLE:
We are features of different species.
We share the same basic plan.
We develop from the same embryonic tissue.
We come from a common ancestor.
We may now do different jobs.
The human arm, the bat wing and the whale flipper are examples of us.
Who am I?
ANSWER: HOMOLOGOUS STRUCTURES
EXPLANATION:
Homologous structures share an origin but may differ in function.
6. RIDDLE:
We are features of different species.
We do the same job.
We look alike on the outside.
We have different basic plans and origins.
We arise by convergent evolution.
The wing of an insect and the wing of a bird are examples of us.
Who am I?
ANSWER: ANALOGOUS STRUCTURES
EXPLANATION:
Analogous structures have the same function but different origins.
7. RIDDLE:
I am a kind of genetic drift.
I follow a sudden, sharp fall in population size.
Disease, disaster or hunting can cause me.
I reduce genetic variation.
Cheetahs and northern elephant seals still carry my mark.
I am named after the narrow neck of a bottle.
Who am I?
ANSWER: BOTTLENECK EFFECT
EXPLANATION:
A bottleneck leaves a small, less varied population.
8. RIDDLE:
I am a kind of genetic drift.
I happen when a few individuals start a new population.
The new population carries only part of the original gene pool.
Rare alleles can become common because of me.
Isolated island and religious communities often show me.
I am named after the individuals who start the new population.
Who am I?
ANSWER: FOUNDER EFFECT
EXPLANATION:
In the founder effect, a new population starts from a few individuals.
9. RIDDLE:
I am a mechanism of evolution.
I act on variation in a population.
I favour individuals better suited to their environment.
The favoured individuals leave more offspring.
Charles Darwin and Alfred Russel Wallace proposed me.
I am known as "survival of the fittest".
Who am I?
ANSWER: NATURAL SELECTION
EXPLANATION:
Natural selection is the differential survival and reproduction of better-adapted individuals.