Untitled Deck Flashcards
Why are many interactions between members of the same species agonistic?
Members of the same species share the same niche and compete vigorously for limiting shared resources.
What behaviours reduce the risk of injury and death during agonistic interactions?
Individuals posture: display strength/stylize combat without real fighting. This allows assessment of strength without risking injury.
How might such behaviours have evolved?
Encounters leading to injury or death carry considerable risk. Animals that assess relative strength without fighting will have greater fitness.
When attacked, aphids release an alarm pheromone. Why is this behaviour adaptive?
It increases fitness because the dying aphid’s kin (genetically identical sisters and offspring) are warned and can escape.
Define a species using the biological species concept.
A species is a group of actually or potentially interbreeding natural populations that are capable of producing viable and fertile offspring.
Would the moose population in Newfoundland be genetically distinct from the mainland? Why?
Yes, due to the founder effect and genetic drift. Small founding population and reproductive isolation likely led to genetic divergence.
Do you think it is likely that Newfoundland moose will become a different species?
Possible but unlikely without strong reproductive isolation and differential selection over a long time.
Could Homo sapiens speciate into two or more distinct species in the future?
This would require reproductive isolation of human populations over a long period with strong selective pressures or genetic drift.
Why is nitrogen a limiting nutrient despite being 78% of the atmosphere?
Nitrogen gas (N₂) has a strong triple covalent bond and most organisms cannot break it to use the nitrogen.
How would increased nitrogen fertilizers affect plants with nitrogen-fixing bacteria?
If nitrogen is no longer limiting, these plants lose their competitive advantage and may stop forming symbioses with the bacteria.
How do mutualistic interactions affect the introduction of plant species to new environments?
Plants may struggle if their mutualistic partners (e.g., nitrogen-fixing bacteria) are absent in the new environment.
Why do snails in dark woodlands have dark shells, while snails in grasslands have yellow shells?
Natural selection by song thrush predation favors camouflage; dark shells in forests, yellow shells in grasslands.
What is an adaptive trait?
A trait that increases an individual’s fitness compared to others without the trait.
Why might post-reproductive longevity be harmful from an evolutionary standpoint?
Long-lived individuals may compete with their offspring for resources without contributing genes to future generations.
Why might human menopause and longevity be adaptive?
Post-reproductive individuals may increase their inclusive fitness by helping care for offspring and grandchildren.
Describe two events that produce genetic variation in daughter cells during meiosis.
Crossing over – mixes alleles between maternal and paternal homologous chromosomes.
Independent assortment – random combination of maternal and paternal chromosomes in new cells.
Would dominant sex-linked traits be more common in males or females? Explain.
More common in females because they have two X chromosomes, increasing chances of inheriting a dominant sex-linked allele.
When would allele pairs violate Mendel’s Law of Segregation?
During nondisjunction in meiosis, when homologous chromosomes fail to separate properly.
Why is mutation rate higher in prokaryotes than eukaryotes?
Prokaryotes lack sexual reproduction; higher mutation rates increase genetic diversity.
Why are plants and fungi now placed in separate kingdoms?
Plants are photosynthetic with cellulose cell walls; fungi are absorptive heterotrophs with chitin cell walls. They evolved from different protist ancestors.
Give an example of a structural/reproductive character that limits plants to moist environments.
Bryophytes and ferns require water for flagellated sperm to swim to the egg.
Give an example of a character that allows plants to survive in dry environments.
Cuticle to prevent water loss, pollen (no need for water for fertilization), drought-resistant seeds.
Why do fungi have a transient diploid stage?
It allows sexual reproduction and increases genetic variability by mixing genes of two parents.
What evidence shows that atmospheric oxygen accumulated 2.5 billion years ago?
Banded iron formations and red beds indicate the presence of oxygen in oceans and atmosphere.
What biochemical pathway led to the accumulation of oxygen in the atmosphere?
Oxygenic photosynthesis evolved in cyanobacteria.
What type of fossil is a stromatolite?
A trace fossil formed by layers of sediment created by ancient cyanobacteria.
What are the advantages of aerobic respiration?
Yields ~18x more ATP per glucose than fermentation. Likely evolved by modifying photosynthetic electron transport chains.
