Practice questions - with answers (Topic 8-16)

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Final exam practice questions (Topic 8-16). Multiple choice questions: 1. What is the role of the outer membrane in Gram negative bacteria? A. It is an adaptation to staining techniques that tend to damage the cell B. It prevents alcohol to penetrate inside the cell C. It protects the bacteria against antibiotics D. It allows the bacteria to move on its substrate E. It increases the rate of binary fission Answer: C Explanation: Staining techniques do not represent a selective force that leads to adaptation bacteria. The outer membrane is part of the cell wall of Gram-negative bacteria and is dissolved by alcohol. It has no role in the movement of bacteria (unlike the flagellum) and it does not increase the rate of binary fission. The outer membrane prevents antibiotic molecules to penetrate inside the cell. 2. What is one advantage of sexual reproduction? A. Sexual reproduction can eliminate favourable allelic combinations B. Sexual reproduction increases the rate of cell division C. Sexual reproduction leads to multicellularity D. Sexual reproduction can increase the rate of adaptation in a changing environment E. Sexual reproduction always constitutes a disadvantage Answer: D Explanation: Sexual reproduction can eliminate deleterious alleles and deleterious allelic combinations and does not increase the rate of cell division. Sexually reproducing organisms are not all multicellular. Finally, sexual reproduction represents an advantage for organisms by creating new allelic combinations, some being favored by natural selection upon a change in the environment. 3. Why do we consider that placoid scales of Chondrichthyes are teeth derivatives? A. They contain dentine B. They are homologous structures C. They are structurally similar to the teeth of other vertebrates D. They contain enamel E. All of the above Answer: E Explanation: Chondricthyes (e.g. sharks) have placoid scales that derive from teeth evolutionarily speaking since the contain both enamel and dentine, and are considered homologous to the teeth of other vertebrates.

4. Which of the following can lead to the exponential growth of a bacterial population? A. Competition for nutrients B. A population size N equal to the carrying capacity K C. A population size N higher than the carrying capacity K D. Unlimited resources E. An increasing death rate Answer: D Explanation: Competition for nutrients and an increase of death rate are typical of stationary and mortality phases. During the exponential growth of a bacteria population, N (population size) is blow K (carrying capacity) and resources are typically unlimited. 5. In what chronological order did the following traits evolve? A. First the mesoderm, second the notochord, third calcium phosphate bones and fourth the amnion B. First the notochord, second the mesoderm, third calcium phosphate bones and fourth the amnion C. First calcium phosphate bones, second the mesoderm, third the amnion and fourth the notochord D. First the mesoderm, second the notochord, third the amnion and fourth calcium phosphate bones E. First the amnion, second the mesoderm, third the notochord and fourth calcium phosphate bones Answer: A Explanation: The mesoderm evolved first (found in all triploblastic animals), followed by the notochord (chordata), then calcium phosphate bones (ostheicthyes) and finally the amnion (in tetrapods whose reproduction is independent from water). 6. Which of the following biological interactions can be considered interspecific mutualism? A. Two lions cooperating with each other while hunting B. Pollination from a hummingbird feeding on a flower C. A lamprey feeding on the blood of a lake trout D. A population of mussels that have their population size regulated via starfish predation E. A relationship between two individuals from different species and from which only one benefits Answer: B Explanation: Mutualism is a biological interaction between two individuals from different species and in which both individuals receive a benefit. The lamprey is a species that parasites other fish species. Starfish and mussels have a predator-prey relationship.

7. Which of the following is typically found at the lowest trophic levels? A. Chemoheterotrophs B. Photoautotrophs C. Primary consumers D. Carnivores E. Omnivores Answer: B Explanation: Examples of photoautotrophs include plants and algae and are typically found at the lowest trophic levels because they convert solar energy into chemical energy that is further transferred to higher trophic levels (which include chemoheterotrophs, primary consumers, carnivores, and omnivores). 8. Which of the following is not an advantage of the amniotic egg during the development of the embryo? A. Air insulation B. Mechanical protection C. Independence from water D. Gas exchange in a moist environment E. All of the above confer an advantage during the development of the embryo Answer: E Explanation: All options listed were made possible by the evolution of the amniotic egg and confer an advantage as tetrapods colonized land and became more independent from the aquatic environment. 9. Lichens are examples of… A. Predation B. Competition C. Commensalism D. Mutualism E. Parasitism Answer: D Explanation: Lichens are examples of mutualism because both individuals from two distinct species (one alga and one fungus) benefit from one another. The fungus benefits from the sugars produced by the alga through photosynthesis and the alga benefits from the water, minerals, protection provided by the fungus.

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10. What are cyclostomes? A. Vertebrates with jaws B. Invertebrates whose mouth is formed first during embryogenesis C. Tetrapods with lobed fins D. Vertebrates with a circular mouth E. Invertebrates that have an exoskeleton Answer: D Explanation: Cyclostomes are vertebrates without jaws and their mouth is circular. 11. Which of the following cannot explain the species richness found in the tropics? A. Lower extinction rates B. Increased resource partitioning C. More solar energy received D. Increased specialization E. Increased abundance of generalist species Answer: E Explanation: Tropical regions tend to have higher speciation rates and lower extinction rates, as well as increased resource partitioning, specialization and solar energy received. Temperate regions tend to have more generalists than tropical regions. Written answer questions: 1. Based on the following figure, explain the evolutionary importance of lobed-finned bony fish in the transition from water to land of vertebrates. ( 2 marks ). Answer: Evolutionarily speaking, lobed-finned fish are important in the transition of vertebrates from water to land because of the presence (in the fins) of an internal skeleton ( 0.5 mark ) to which muscles can attach ( 0.5 mark ). This allowed the first lobed-finned to craw/walk on substrate ( 0.5 mark ) and live in coastal lands ( 0.5 mark ).

2. Consider a vascular plant with the following life cycle. a) Which of the letters (A, B, C, D, or E) corresponds to the sporophyte? ( 0.5 mark ) b) Is “A” unicellular or multicellular? ( 0.5 mark ) c) Is this organism heterosporous or homosporous? ( 0.5 mark ) d) If “E” produces flagellated cells, which of the letters (A, B, C, D, or E) corresponds to the megasporangium? ( 0.5 mark ) Answer: a) A ( 0.5 mark ) b) Multicellular ( 0.5 mark ) c) Heterosporous ( 0.5 mark ) d) B corresponds to the megasporangium ( 0.5 mark ) 3. Two species of lizards (A and B) have different geographical distributions. The range of their geographical distributions differ in size and overlap slightly at lower latitudes (see Figure below). These two lizard species also exploit different food resources, with species A feeding on a single species of insect while species B feeds on multiple species of insect. a) Which species is likely a generalist? Justify your answer ( 2 marks ). b) Which species is likely to respond better to a long-term change in annual temperature? Justify your answer. ( 2 marks ). You can assume that these two species have the same dispersal abilities and that they are not limited by any geographical barrier. Answer: a) Species B is likely a generalist ( 1 mark ) since it feeds on multiple insect species ( 0.5 mark ) and its geographical distribution is larger (accepted: its natural habitat likely includes a large resource/temperature gradient). ( 0.5 mark ). b) Species B is likely to respond/adapt better to a long-term change in annual temperature ( 1 mark ) because it lives at different latitudes/temperatures and can shift its range more easily (accepted: its natural range is wider and not restricted by physiological factors or species A would be restricted to a limited number of habitats available/by physiological factors). ( 1 mark ).

4. A Type III survival curve corresponds to an r-strategy or K-strategy? Justify your answer based on survival rates and the investment into parental care. ( 3 marks ). Answer: An r-strategy corresponds to a Type III survivorship curve ( 1 mark ). This is because r-strategies are typical of species with … • a high juvenile death/mortality rate (low adult death/mortality rate) such as in the Type III survivorship curve (as seen in the rapid drop in the juveniles). ( 1 mark ). • a limited investment into parental care despite the production of many offspring ( 1 mark ). 5. Bighorn sheep and pronghorns are two mammal species that almost went extinct in the early 20 th century because of unregulated hunting. Demographic studies of two populations from Alberta (one of each species) indicate that both species are still declining locally and that more remains to be done to adequately protect them. The figure below represents the survivorship curves of each species (bighorn sheep: top curve in blue, pronghorn: bottom curve in red). a) What type of survivorship curve is depicted for each species? ( 1 mark ). b) Genetic data suggest that the pronghorn population has a low and rapidly decreasing genetic diversity and that individuals have low average fertility. Name and explain the biological phenomenon likely causing this. ( 1 mark ) c) Suggest a simple strategy that could help rescue the pronghorn population. ( 1 marks ). Answer: a) The pronghorn population shows a type II survivorship curve. ( 0.5 mark ) and the bighorn sheep population shows a type I survivorship curve. ( 0.5 mark ). b) This can be caused by an extinction vortex ( 0.5 mark ) where the small population size causes genetic diversity to be low OR increases genetic drift, which increases inbreeding depression, which lowers individual fitness OR fertility which reduces the population size even more. ( 0.5 mark ). c) The pronghorn population could be rescued by, any of the following for 1 mark: • the introduction of individuals from other another population to increase the genetic diversity • increase the population size somehow • manage their breeding to minimize mating between relatives • induce mutation • Note: Introducing individuals from a different species is not acceptable unless it specifically said that it’s a close relative that can mate and produce fertile offspring with the pronghorns. • Answers that introduce conservation strategies, but do not address to increase the genetic diversity of the population should be awarded 0.5 marks.

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6. Two students (A and B) independently perform a mark-recapture experiment to estimate the population size of the same bighorn sheep population in a natural reserve (Alberta, Canada). The population sizes that they estimate differ as follow: • Student A estimates the population size to be 254 • Student B estimates the population size to be 228 Explain two possible causes for this discrepancy. For each, provide an example of how this could occur. ( 4 marks ). Answer: 2 among the following ( 2 marks each): • Marked and unmarked individuals have a different probability of being sampled. ( 1 mark ). For example, if shy individuals are rarely/never caught (or bold are caught more often). ( 1 mark ). • The marking of individuals affected the probability of one individual to be re-sampled ( 1 mark ). More experienced individuals were sampled more often ( 1 mark ). • Marked individuals have not mixed completely back into the population ( 1 mark ). The marked individuals may have stayed near the sampling location ( 1 mark ). • Population demographics may have influenced the sampling during the re-sampling interval. ( 1 mark ). Some individuals were either born, have died, have immigrate or have emigrate ( 1 mark ). 7. Two plant species (A and B) that are endemic to Northern Ontario have been monitored since 2002. Each species consists of a single population with a very restricted geographical distribution. Each year, researchers measure the average distance between new seedlings of each species and the center of their respective population. Following the reintroduction in 2014 of the Franklin's ground squirrel ( Poliocitellus franklinii ), researchers were interested in its ecological effect on both plant species. Below is a graph that shows, for each plant species, the average distance of new seedlings from the center of their respective population before and after the reintroduction of ground squirrels. a) What effects did the squirrel reintroduction have on the geographical distribution of each species. Answer separately for species A and for species B. ( 1 mark ). b) Formulate two simple hypotheses (one for species A and one for species B) to explain why this may have occurred, focusing on the modes of dispersion for each plant species. For each of your two hypotheses, justify your answer by highlighting which data in the graph you are comparing. ( 2 marks )

Answer: • The Franklin’s ground squirrel increases the geographical distribution/range of species A ( 0.5 mark ) The Franklin’s ground squirrel does not increase the geographical distribution/range of species B ( 0.5 mark ) • The seed dispersal of species A is done through zoochory (accepted: animal-facilitated, transported by squirrels) ( 0.5 mark ) because in the presence of squirrels the dispersal distance is increased (red in 2015 compared to red in 2007, accepted: ~2km increase). ( 0.5 mark ) • The seed dispersal of species B is done through anemochory (accepted: wind-facilitated, transported by wind) ( 0.5 mark ) because it does not depend on the presence of the squirrel (similar distance in blue between 2007 and 2015, accepted: ~ a few hundred meters). ( 0.5 mark ). OR concept of preference for species A over B and provide an explanation for how this influences dispersal. 8. The Alder leaf beetle ( Agelastica alni ) is commonly found in Southern Ontario and mainly feeds (unsurprisingly) on alder leaves. In 1974, the Green tortoise beetle ( Cassida viridis ) was introduced to the same region by accident, and it is now considered an invasive species. The Green tortoise beetle feeds on low vegetation such as herbaceous plants, as well as higher vegetation such as the leaves of many trees, including alders. The diagram below depicts the preferred feeding habitat of each species. What consequences could the introduction of the Green tortoise beetle have on the ecological niche of the Alder leaf beetle. Justify your answer. ( 3 marks ). Answer: One of the two reasonings below. Reasoning 1 • Concept 1: The Green tortoise beetle competes for similar resources to the ones used by the Alder leaf beetle (or alder leaves) (accepted: its niche overlaps the Alder leaf beetle’s niche or it is a generalist or it uses a wide variety of resources). ( 1 mark ). • Concept 2: This competition may limit the growth/survival/fitness of the Alder leaf beetle ( 0.5 mark ) and cause it to occupy a smaller niche (accepted: it will occupy its realized niche). ( 0.5 mark ). • Concept 3: This could even lead to the local elimination (accepted: extinction or competitive exclusion) of the Alder leaf beetle. ( 1 mark ).

Reasoning 2 • Concept 1: The Green tortoise beetle is a generalist, some of its resources are similar to (accepted: overlap with) the ones used by the Alder leaf beetle, a specialist. ( 1 mark ). • Concept 2: The Green tortoise beetle can be outcompeted by (have a lower growth/fitness/survival than) the Alder leaf beetle for the higher vegetation (Alder leaves). ( 0.5 mark ) and may occupy the lower habitat (lower vegetation) ( 0.5 mark ). OR there will be resource partitioning between the species and differentiation of ecological niches ( 0.5 mark ) which will decrease competition which allows both species to coexist ( 0.5 mark ). • Concept 3: The Alder leaf beetle may remain in/occupy its fundamental niche (accepted: natural/original niche) ( 1 mark ).

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Practice questions - with answers (Topic 8-16)

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