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BIOLOGY 200 SAMPLE WORD
PROBLEMS 2025-2026. QUESTIONS
WITH CORRECT AND VERIFIED
ANSWERS. A+ GRADED.
Explain four features that can be used to distinguish members of the Domain Bacteria from the Domain Archaea
a) RNA sequence
b) Archaeal membrane lipid tails are branched and sometimes linked.
c) Some bacteria can photosynthesize
Bacterial cell walls contain some peptidoglycan, Archaea do not
Structure usually relates to function in living organisms. Illustrate this concept by providing and explaining three broad examples of structural advances in organisms discussed in class or in the text readings in the section of this course that were associated with new evolutionary functions
i) Flagellum in bacteria permits locomotion
ii) Multicellularity permits the capacity for specialization of tissues within an organism (e.g. plant roots and shoots)
iii) Membrane-bound organelles permit cellular organization and localizes specific metabolic processes (e.g. yeast cell of Phylum fungi)
Describe two distinct features of viruses that allow them to evolve extremely rapidly
Extremely rapid reproduction in host cell
Extremely large number of progeny per reproductive event
Nucleic acid reassortment can occur when two strains infect the same cell (antigenic shift).
Viruses have been detrimental to human societies in many different ways. Support this statement using three separate examples
i) Viruses cause many serious human diseases (e.g. COVID 19).
ii) In the history of human colonisation, virus transmission to societies that had not developed immunity resulted in major local population declines (e.g. Incans, Mexicans, North American Indigenous peoples)
iii) Viruses could be used a bioterrorism weapon (e.g. anthrax)
We now live, as Earth always has, in an Age of Bacteria. These simplest organisms will dominate our planet (if conditions remain hospitable for life at all) until the sun explodes." Stephen J Gould, 1998. This famous biologist considered Prokaryotes as relatively 'simple' organisms compared to Eukaryotes. Make two points in favour of (2 x 0.5 marks), and two points against this conclusion
Points in favour:
No nucleus
No/little membrane compartmentation
Unicellular (only)
No cytoskeleton
No sexual reproduction
The diverse and unique metabolic capabilities of prokaryotes is critical to the biogeochemical cycling of many growth-limiting nutrients (N, P, Ca, etc) and therefore to the ongoing availability of these nutrients to Eukaryotes, thereby providing the resources necessary for their growth and diversification
Provide two reasons to explain why prokaryotes are generally only metabolically active when their cells are in contact with external water
Prokaryotic cells are reliant on an external water film around them so that:
a. diffusion can supply nutrients and organic matter
b. diffusion will remove waste excretions
c. water is necessary as a metabolite
Explain what is meant by the term chemoautotroph to describe an organism's metabolism in terms of its acquisition of energy (1 marks) and carbon (1 marks), and briefly describe an example of a globally significant biogeochemical reaction that is mediated by a chemoautotroph
A chemoautotroph obtains its energy by chemical oxidation of a reduced compound such as Fe2+, NH4+, S, CH4, and its carbon by reducing CO2 (or HCO3) gas to an organic compound such as carbohydrates.
Chemoautotrophs have globally significant and critically important impacts on the biogeochemical cycling of:
i) iron oxidation (iron-oxidizing bacteria are responsible for some rusting and rock weathering)
Describe two lines of evidence supporting the hypothesis that life evolved in deep sea thermal vents
i) Thermophiles are particularly frequent at the base of the Tree of Life
ii) The reducing conditions in vents are consistent with the biochemical traits of early life forms (heterotrophic, and anaerobic)
Make four points in favour of the view that viruses are not living organisms
i) Require host cell to replicate.
ii) Do not grow either by size increase or by dividing.
iii) Cannot respond to external stimuli.
iv) Lack cellular structures.
Elucidating the fundamental biology of viruses has been beneficial to human societies in many different ways. Give an example to demonstrate this point ( mark), and clearly explain the societal benefit
i) Understanding smallpox and its relation to cowpox led to the development of vaccines as an immunization preventative medical procedure.
ii) Understanding that many viruses function as bacteriophages has resulted in the development of very important tools in molecular biology to conduct gene transfers and cloning.
Indicate where the processes of cytoplasmic fusion (plasmogamy) and nuclear fusion (karyogamy) occur in the above diagram using labelled arrows
In this fungus (within the Zygomycota), once mating begins, cytoplasmic fusion (plasmogamy) is immediately followed by nuclear fusion (karyogamy) during formation of the zygospore.
Briefly describe an ecological context that can promote the onset of sexual reproduction in these fungi
The fungus is likely to begin sexual reproduction producing the zygospore once either
a) the food resource is depleted
b) the environmental conditions become harsh
Fungi are more important than bacteria and archaea as decomposers of dead plant and animal organic matter in terrestrial ecosystems. Make three points to support this statement
· Fungi can have a hyphal growth form that allows them to grow toward and within their substrate
· Fungi can synthesize specialised wood decay enzymes
· Fungi may be better adapted than bacteria to dispersal on land because they can produce large fruiting bodies to release spores into the air and so disperse to other organic matter substrates
Compare and contrast fungal and vascular plant reproduction by describing three distinctive features of the genetics and lifecycles of the Kingdom Fungi
i) Sexual reproduction is by zygotic meiosis in most fungi whereas vascular plants have an alternation of generations life cycle.
ii) Zygotic (diploid) stage in fungi is unicellular and often represents the dormant highly protected stage of the life cycle that is favoured when environmental conditions are not favourable for growth.
i) Asexual reproduction is extremely common in most fungi, but in a much smaller proportion of vascular plants.
The Kingdom Fungi contains many distinctive biological features compared to the other eukaryotic Kingdoms. List four clearly separate and distinct biological characteristics of the Fungi to support this statement
- Individual fungi can extend across a very wide range of spatial scales (microns to kilometers)
- Fungi represent a very large number of the total species on Earth (Expected total number on Earth is second only to Insects )
- Fungi form a very diverse range of symbiotic partnerships1. Fungi have cell walls made of chitin
Dry rot' refers to decomposition of wood in a dry environment by certain fungi. Outline two distinctive features of these fungi that allow them to achieve this process?
i) Certain dry rot fungi can synthesize substantial liquid water as a byproduct of glycolysis
Illustrate this concept using four clearly separate and distinct examples that you have learnt about in this course
i) Diversity in plasmamembrane folding may have led to the evolution of the nuclear membrane within an ancestral eukaryotic cell and thus to enhanced levels of complexity and compartmentation, signaling and trafficking that ultimately contributed to the evolution of much more complex organisms (e.g. the possibility of post-transcriptional modification of mRNA in the cytosol contributes to enhanced genetic diversity).
i) Diversity in primitive roots (rhizoids) in certain green algae were a precursor to the evolution of much more advanced roots in the highly diverse vascular plants.
i) Diversity in bacterial metabolism permitted primary endosymbiosis because the process involved those particular bacteria that had evolved a capacity for aerobic respiration. This primary endosymbiosis ultimately gave rise to the first heterotrophic eukaryotes and so was a starting point for extraordinary subsequent diversification across the Eukarya.
ii) Diversity in the evolution of the photosynthetic bacteria resulted in some that produced oxygen (cyanobacteria) ultimate resulted via primary endosymbiosis in the first photosynthetic eukaryotes which went on to diversify greatly.
The diagram above illustrates a fundamental life cycle trend in the evolution of diversity across the Tree of Life since life first originated.
a) Describe the trend across the four life cycles using appropriate biological terminology (3 marks)
The first organisms were prokaryotes with single copies of their chromosomes and thus only capable of reproduction by fission resulting in two daughter cells that were almost genetically identical (except for mutation) in each life cycle.
The biological functioning of both aquatic and terrestrial ecosystems is primarily dependent on energy derived from photosynthesis.
Write out the 'equation of life' that includes both autotrophic and heterotrophic components and includes energy inputs and outputs
(HCHO)n+O2--> CO2+H20+ ENERGY
Why are most photosynthetic organisms in aquatic systems generally small and structurally undifferentiated compared to their counterparts on land (
The water medium in aquatic environments provides buoyancy to keep the photosynthesizing organism up close to the top surface where light availability is highest, and where there is ready diffusion of critical nutrients such as N, P, and dissolved CO2. Consequently, there is no selection pressure for complex structural tissues
Electricity generation facilities in many parts of the world today are dependent on diverse ancestral members of the Fern group (Pteridophytes). Explain this statement
The Pteridophytes include lycophytes, horsetails and ferns all of which grew in abundance in tree-like forms in the Carboniferous period about 360-290 mya ago. Growth conditions were ideal in terms of warm temperatures and lots of rainfall and so huge forests developed
specific features of seeds (2 x 0.25 marks), and in each case explain one evolutionary fitness benefit of that feature compared to spores (2 x 1.5 marks).
Protective outer seed coat allows dormancy for days to years, until conditions are favourable for germination
The seed's internal nutrient-storing cells are nutrient reserves that allow the germinating seed to fully establish itself without immediate reliance on its environment
The seed's embryo is deeply protected by both the external surface seed coat and the internal nutrient-rich enclosing tissue
Agriculture is in fact a brilliant if unconscious evolutionary strategy on the part of certain plants and animals to get humans to advance their interests" (Michael Pollan, Omnivores Dilemma, 2006). Write a series of logically ordered statements to explain the evolutionary biology underlying this statement using the example of maize (sweet corn; Zea mays) arising from its ancestral ancestor Teosinte (both pictured above) within the Grass family (6 marks).
· Maize evolved from an ancestral grass plant (Teosinte) that is native to C. America.
· Teosinte produces a small cob at the top of the plant and each kernel is covered by a hard coating.
Trade-offs are a very common feature in evaluating the fitness benefits and costs of particular evolutionary traits.
Evergreen needle-leaf and deciduous broad-leaf tree species tend to occupy distinctly different habitat-types. The former are generally slow-growing and more
abundant at relatively high latitudes and altitudes (e.g. boreal and alpine habitats where soil moisture can be scarce at some times of year), whereas deciduous broadleaf trees tend to be faster-growing but confined to lower latitude and altitude sites where soils are usually more moist.
Name representative species (common or scientific name) of an evergreen needle- leaf tree and of a deciduous broad-leaved tree that might be found growing on the Queen's campus
Pine, Cedar, Spruce, Fir.....(Note: strictly speaking Tamarack/Larch is needle- leaved but deciduous, and therefore not a correct answer - maybe give 0.5 mark to be generous);
Maple, Oak, Ash, Beech.....
By considering the trade-off associated with their differences in leaf surface area/volume ratio, explain why each of these tree groups is best adapted to the soil moisture characteristics of their particular habitat-type. In your answer, be sure to clearly specify both the benefit as well as the associated cost for why evergreen needle-leaved species tend to dominate on relatively dry soils (2 x 1 marks), and a specific benefit and a cost for why deciduous broad-leaved species tend to dominate on more moist soils
Evergreen needle-leaf trees have a relatively small leaf surface area relative to volume and the benefit of this trait is that it minimizes leaf water loss. Therefore, it allows these species to dominate in habitats where soil moisture is scarce (desiccation-resistant). The disadvantage of small leaf surface area relative to volume is that photosynthetic capacity is low, resulting in relatively slow growth rates
Phosphorus - ATP energy, Phospholipids in membranes, Nucleotide phospho- ribose backbone in DNA/RNA, phosphate sugars in metabolism, Bones in vertebrates - made of calcium phosphate, Phosphate for signalling...???
a) Name two other essential nutrients that vascular plants generally obtain from soil (2 x 0.75 marks)
Potassium
Calcium
Magnesium
Sulphur
Some plant species have evolved specialized traits to obtain significant components of their nutrition from animals or from other plants. Explain this statement by describing three distinct examples that were discussed in lecture or in the textbook readings of plant nutrient acquisition involving other organisms
Sundew plants trap flies with sticky glues on their leaves, and then slowly digest the trapped insects by exuding digestive enzymes.
Pitcher plants form funnel-like shoots that trap insects and even frogs... and the slippery coating on the inside coupled with a multitude of downward point hairs prevent escape.Digestive enzymes in the funnel's internal liquid pool at the base decompose the prey
a) Angiosperms contain enormous structural diversity. Give two distinct examples of conventional roots that have become modified by evolution into other structures (2 x 1 marks).
Evolution within the angiosperms has resulted in modification of conventional roots into storage roots (e.g beetroot), prop roots (e.g. maize), green roots (e.g. epiphytes such as orchids), cluster roots (e.g. Proteaceae of phosphorus- impoverished soils)...?
Some plants can have relatively low root:shoot biomass ratios. Explain the evolutionary selection pressure that would lead toward evolution of a low root:shoot biomass ratio, and describe the likely environmental properties of a habitat-type where such evolution would likely occur (
Shoots are critical to providing photosynthetic capacity....while roots provide access to soil nutrients and water.
A plant species is likely to evolve toward biomass allocation to organs that enhance uptake of the most growth-limiting resources.
Angiosperms contain enormous structural diversity. Give two distinct examples of leaves that have become modified by evolution into other structures
Evolution within the angiosperms has resulted in modification of leaves into tendrils, hairs, reproductive leaflets, spines, and storage leaves (such as in onion)....?
When a potato is stored in a cupboard or dark area for too long, the "eyes" of the potato will often produce new shoots. Based on this information, and the basic structural design of plants, explain how we know that a potato tuber is an example
