NECO Senior School Certificate Examination · Biology and General Science

Genetics, Heredity, Evolution and Ecology

35 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 35 questions

  1. In a cross between two heterozygous tall pea plants (Tt × Tt), what is the expected phenotypic ratio among the offspring according to Mendel's law of segregation?
  2. In a dihybrid cross between two plants heterozygous for seed shape and seed color (RrYy × RrYy), what phenotypic ratio is predicted by the law of independent assortment?
  3. When pure-breeding red four o'clock flowers (Mirabilis jalapa) are crossed with pure-breeding white flowers, all F1 offspring bear pink flowers. What genetic phenomenon does this illustrate?
  4. A man with blood group AB marries a woman with blood group O. What are the possible blood groups of their biological children?
  5. In humans, sickle cell hemoglobin (HbS) is inherited as a codominant allele. If two carrier parents with sickle cell trait (HbA HbS × HbA HbS) have a child, what is the probability that the child will…
  6. Why is sex-linked red-green color blindness substantially more prevalent among human males than among females?
  7. Under what parental combination can Rhesus incompatibility disease (erythroblastosis fetalis / hemolytic disease of the newborn) occur in a second or subsequent pregnancy?
  8. Which of the following human traits is an example of continuous phenotypic variation governed by polygenic inheritance?
  9. What specific molecular point mutation in the beta-globin gene causes normal hemoglobin (HbA) to be converted into sickle cell hemoglobin (HbS)?
  10. What chromosomal abnormality causes Down syndrome (mongolism) in humans?
  11. During the Industrial Revolution in England, why did dark-colored melanic peppered moths (Biston betularia) become predominant over light speckled moths in polluted industrial regions?
  12. Which anatomical structure provides compelling comparative anatomical evidence of divergent evolution from a common ancestral vertebrate lineage?
  13. Which of the following structures in the human body is considered a vestigial evolutionary remnant of little or no current functional significance?
  14. Which ecological biome covers the northernmost belt of Nigeria and is characterized by sparse thorny acacia trees, drought-resistant grasses, and very low annual rainfall?
  15. What ecological term describes the symbiotic relationship between leguminous plants (such as cowpeas) and Rhizobium bacteria inhabiting their root nodules?
  16. In an ecological food chain: Grass -> Grasshopper -> Toad -> Organism X -> Hawk. If Organism X feeds directly on toads and is preyed upon by hawks, identify Organism X:
  17. Why does only approximately 10% of energy transfer from one trophic level to the next consecutive level in an ecological pyramid of energy?
  18. Why is an ecological pyramid of energy always upright and can never be inverted in any natural biological ecosystem?
  19. In the global biogeochemical carbon cycle, which natural process directly extracts carbon dioxide from the atmosphere to store carbon in organic compounds?
  20. Which genus of soil bacteria converts toxic nitrites (NO₂⁻) into plant-absorbable nitrates (NO₃⁻) during biological nitrification in agricultural soil?
  21. What ecological term describes the symbiotic relationship between epiphytic orchids growing on the high branches of tall rainforest trees?
  22. What type of ecological succession occurs when an abandoned slash-and-burn cassava farmland is left fallow to regrow natural vegetation?
  23. What is the stable, self-perpetuating final ecological plant community that develops at the end of a long ecological succession called?
  24. What ecological instrument is used in field studies to measure physical relative humidity in a forest understory?
  25. What ecological sampling tool is commonly used to estimate the population density of small herbaceous weeds or snails in an open savanna grassland?
  26. Why is the tropical rainforest biome characterized by multiple distinct vertical strata (canopy layers) of vegetation?
  27. What morphological adaptation enables xerophytic plants like cacti and Euphorbia to survive in arid desert environments?
  28. What anatomical adaptation enables hydrophytic plants like water lettuce (Pistia) and water hyacinth to float buoyantly on water surfaces?
  29. In population ecology, what term describes the maximum population size of a biological species that a particular environment can sustainably support?
  30. What type of population growth curve is characterized by an initial lag phase, rapid exponential acceleration, and deceleration as the population approaches carrying capacity?
  31. Which mechanism of reproductive isolation prevents interbreeding between two sympatric species because they breed at different times of the year?
  32. What evolutionary term describes the independent development of similar hydrodynamic body forms in unrelated organisms like dolphins (mammals) and sharks (cartilaginous fish)?
  33. Which cellular organelle possesses its own circular DNA and 70S ribosomes, providing strong evidence for the endosymbiotic theory of eukaryotic cell origin?
  34. What term describes the natural variation in allele frequencies that occurs purely by chance in small, isolated biological populations?
  35. What is the primary conservation objective of establishing National Parks like Yankari Game Reserve in Bauchi State, Nigeria?

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