Midterm 2 Practice Questions

1. What are the most basic taxonomic divisions of life?

   1. Eukarya, Archaea, and Bacteria.

   2. Bacteria and Eukarya.

   3. Animalia and Bacteria.

   4. Bacteria, Archaea, and Animalia.

   5. Archaea and Eukarya.

2. Approximately how far back in time does the fossil record extend?

   1. 3.5 million years.

   2. 5.0 million years.

   3. 3.5 billion years.

   4. 5.0 billion years.

3. Scientists identified a layer of fossils that represents a major decline in biodiversity followed by a period of low diversity. Which explanation best fits this pattern?

   1. Fossilization only occurred in one region, skewing biodiversity data.

   2. An adaptive radiation event led to a burst of new species.

   3. A mass extinction event caused a loss of biodiversity, followed by gradual recovery.

   4. Organisms evolved larger sizes over time, limiting biodiversity in the record.

   5. Fossils in this layer only represent a single type of organism, suggesting no biodiversity changes.

4. Following a volcanic eruption that creates isolated habitats, a group of small mammals is found to diversify into several species, each with unique adaptations to the island's niches. What process best explains this diversification?

   1. Coevolution with local flora

   2. Adaptive radiation due to new ecological opportunities

   3. Convergent evolution with unrelated species

   4. Environmental resistance to genetic drift

   5. Gradual replacement of previous mammals through gene flow

5. The Great Oxygenation Event from 2.7 to 2.3 billion years ago __________________.

   1. Increased prokaryote diversity.

   2. Was caused by phototrophic eukaryotes.

   3. Was caused by ancient colonial prokaryotes known as stromatolites.

   4. Was attributable to cyanobacteria.

   5. Was advantageous for early prokaryotes.

6. The Miller-Urey experiment demonstrated the synthesis of amino acids under conditions similar to early Earth. What important concept did this experiment support in the context of life's origins?

   1. The first cells formed directly from amino acid clusters.

   2. Early Earth conditions favoured complex molecules rather than simple ones.

   3. Life began with DNA formation under simple environmental conditions.

   4. Organic molecules could form abiotically, providing building blocks for life.

   5. Amino acids only form under controlled laboratory conditions.

7. Match the numbered terms to the description that follows. Choose all the appropriate terms. Description: a prokaryote that obtains both energy and carbon as it decomposes dead organisms.
   1. Autotroph; 2. Heterotroph; 3. Phototroph; 4. Chemotroph

   1. 1, 3, and 4

   2. 1 only

   3. 4 only

   4. 2 and 4

   5. 1 and 3

8. A bacterial strain isolated from an industrial waste site is capable of breaking down complex organic compounds and exhibits a thick layer of peptidoglycan in its cell wall, which stains purple in a Gram test. To which group of bacteria does this strain likely belong?

   1. Proteobacteria

   2. Cyanobacteria

   3. Gram-positive bacteria

   4. Archaea

   5. Spirochetes

9. Bacterial transduction is ________________.

   1. Transfer of genetic material between prokaryotic cells via a pilus.

   2. Incorporation of foreign DNA from the surrounding environment.

   3. Transfer of genetic material between prokaryotic cells via bacteriophage.

   4. A mode of unidirectional horizontal gene transfer that can lead to the rapid spread of antibiotic resistance.

   5. Genetic recombination during sexual reproduction between two bacteria.

10. Which of the following nutritional modes are only found in prokaryotes?

    1. Photoautotrophs.

    2. Photoheterotrophs.

    3. Chemoautotrophs.

    4. Chemoheterotrophs.

    5. Two of the above are correct.

11. Which of the following groups is known for living in extreme environments, such as salt lakes and hot springs?

    1. Cyanobacteria

    2. Gram-positive bacteria

    3. Archaea

    4. Proteobacteria

    5. Spirochetes

12. Given the wide range of habitats inhabited by prokaryotes, how does their diversity in nutritional modes contribute to their ecological success?

    1. Their ability to use various energy sources and carbon substrates allows them to thrive in many environments, including extreme ones.

    2. They rely solely on photosynthesis for energy, dominating well-lit environments.

    3. They have specialized nutritional modes that limit them to specific niches.

    4. They rely on animal hosts for nutrition, limiting their ecological success to symbiotic relationships.

    5. They only utilize organic compounds for energy and carbon, restricting them to nutrient-rich environments.

13. Rhizobium species are ___________________.

    1. Common pathogens in soils.

    2. Chemoheterotrophic decomposers in soils.

    3. Phototrophic mutualists of lichens.

    4. Endosymbiotic mutualists of leguminous plant roots.

    5. Phototrophic, nitrogen-fixing soil bacteria.

14. Which of the following is characteristic of the Chlamydias clade of bacteria?

    1. Free-living, heterotrophs.

    2. Peptidoglycan is absent from the cell wall.

    3. Mutualists in the intestines of many mammals.

    4. Chemoheterotrophic decomposers.

    5. Gram-positive cell walls.

15. Which term describes an interaction where one organism benefits at the expense of another?

    1. Commensalism

    2. Mutualusm

    3. Competition

    4. Symbiosis

    5. Parasitism

16. How does horizontal gene transfer between prokaryotes challenge the traditional view of a "tree of life" based on vertical descent from common ancestors?

    1. It demonstrates that mutations are the sole contributors to genetic diversity.

    2. It suggests that species evolve in isolation, without exchanging genes.

    3. It implies that genetic material can be shared between unrelated species, resulting in a more "network-like" evolution.

    4. It shows that prokaryotes evolve slower than previously thought.

    5. It proves that only plasmids, not chromosomal DNA, are exchanged during reproduction.

17. Scientists studying a population of soil bacteria found that these bacteria are highly genetically diverse, despite reproducing through binary fission. Upon further investigation, they discovered that bacteria in this environment frequently exchange DNA with other bacteria in the soil. What is the most likely explanation for this high genetic diversity?

    1. The bacteria form endospores when conditions are unfavorable.

    2. The bacteria mutate rapidly during binary fission.

    3. The bacteria reproduce at an unusually high rate.

    4. The bacteria undergo high rates of conjugation and transformation.

    5. The bacteria use transduction to prevent gene exchange.

18. Which of the following statements best distinguishes eukaryotic cells from prokaryotic cells?

    1. Eukaryotes contain membrane-bound organelles, including a nucleus, while prokaryotes do not.

    2. Eukaryotic cells are exclusively multicellular, whereas prokaryotic cells are always unicellular.

    3. Eukaryotes have circular DNA stored in the nucleus, whereas prokaryotes have linear DNA in the cytoplasm.

    4. Eukaryotic cells lack ribosomes, while prokaryotic cells possess ribosomes for protein synthesis.

    5. Eukaryotic cells perform photosynthesis, while prokaryotic cells do not.

19. Green algae differ from plants in that many green algae ___________________.

    1. Are heterotrophs.

    2. Have plastids.

    3. Are unicellular.

    4. Have cell walls containing cellulose.

    5. Have alternation of generations.

20. Three key reproductive adaptations of seed plant evolution include ___________________.

    1. Sporophylls, strobili, ovules.

    2. Homospory, spores, dominant sporophyte.

    3. Dominant sporophyte, spores, ovules.

    4. Dominant gametophyte, cones, seeds.

    5. Dependent gametophyte, seeds, pollen.

21. The evolution of plants is marked by decreasing dependence on water for dispersal and fertilization. In which of the following taxon pairs are dispersal and fertilization, respectively, independent of water?

    1. Non-vascular plants and charophytes.

    2. Gymnosperms and non-vascular plants.

    3. Bryophyta and Coniferophyta.

    4. Anthophyta and Lycophyta.

    5. Seedless vascular plants and Monilophyta.

22. Angiosperms' success and adaptability can be attributed to their unique reproductive adaptations, primarily:

    1. Reliance on photosynthesis over other forms of nutrient acquisition.

    2. The development of complex root systems that prevent soil erosion.

    3. Strong preference for shaded, moist environments.

    4. Their limited genetic diversity, which stabilizes populations.

    5. The evolution of flowers and fruit, enabling specialized pollination and seed dispersal strategies.

23. The structural arrangement of flowers in angiosperms supports a highly specialized reproduction system. What feature of flowers most directly contributes to their efficiency in attracting specific pollinators?

    1. Large, flat leaves surround the flower

    2. Brightly coloured petals and specific scents

    3. Increased photosynthetic tissue within the petals

    4. Presence of a hardened fruit surrounding the flower

    5. Self-pollination mechanisms

24. Which of the following statements about Angiosperms is incorrect?

    1. Gametophytes produce gametes by mitosis.

    2. The ovary always develops into fruit, even if no ovules are fertilized.

    3. The pollen tube discharges two sperm cells into the embryo sac.

    4. The endosperm develops only after double fertilization.

    5. Megasporangium produces four megaspores by meiosis.

25. How does double fertilization benefit angiosperms in resource allocation during seed development?

    1. It reduces the amount of energy expended in producing seeds.

    2. It results in only a single fertilization event, conserving resources.

    3. It allows the formation of endosperm only when fertilization has occurred, ensuring nutrient investment only in viable embryos.

    4. It eliminates the need for pollen.

    5. It produces an additional seedling for each ovule.

26. Which of the following features is typical of most fungi?

    1. Cell walls are composed of cellulose

    2. Photosynthetic cells

    3. Hyphal structures form a mycelium

    4. Chloroplasts for energy production

    5. Multicellular bodies with chlorophyll

27. Which of the following statements best describes how the characteristics of fungi reflect their role in ecosystems?

    1. The presence of chloroplasts enables fungi to act as primary producers

    2. The absorptive mode of nutrition enables fungi to decompose complex organic matter

    3. Fungi's multicellularity allows them to compete with plants for sunlight

    4. The absence of chloroplasts restricts fungi to aquatic habitats

    5. Fungi lack cell walls, allowing flexibility in nutrient absorption

28. Fungal hyphae and mycelia are often highly branched and thin. What is the primary advantage of these structures for fungi in nutrient-limited environments?

    1. They allow rapid movement to new locations

    2. They maximize surface area for nutrient absorption

    3. They limit fungal growth to small, confined spaces

    4. They reduce the rate of water loss in dry conditions

    5. They enable efficient spore dispersal

29. In asexual reproduction, fungi produce spores through which process?

    1. Binary fission

    2. Photosynthesis

    3. Fertilization

    4. Mitosis

    5. Meiosis

30. Which feature of fungal structure and function contributes most directly to their efficiency as decomposers?

    1. Thick, multi-layered cell walls for structural support

    2. A high concentration of chlorophyll captures light energy

    3. Enzyme secretion that breaks down complex molecules outside the cell

    4. The ability to produce specialized reproductive structures

    5. Rigid hyphal walls to protect against physical damage

31. Which of the following is a characteristic of hyphate fungi (fungi featuring hyphae)?

    1. They acquire nutrients by phagocytosis.

    2. They are adapted for rapid directional growth to new food sources.

    3. Their body plan is a unicellular sphere.

    4. Their cell walls consist mainly of cellulose microfibrils.

    5. They reproduce asexually by a process known as budding.

32. What are the sporangia of the bread mould Rhizopus?

    1. Asexual structures that produce haploid spores.

    2. Asexual structures that produce diploid spores.

    3. Sexual structures that produce haploid spores.

    4. Sexual structures that produce diploid spores.

33. In most fungi, karyogamy does not immediately follow plasmogamy, which consequently ____________________.

    1. Means that sexual reproduction only occurs in specialized above-ground structures.

    2. Results in multiple diploid nuclei per cell.

    3. Allows fungi to reproduce asexually most of the time.

    4. Results in heterokaryotic or dikaryotic cells.

    5. Is strong support for the claim that fungi are not truly eukaryotic.

34. How does mycorrhizal association benefit both the fungi and the plant in nutrient-poor soils?

    1. The fungi supply organic nutrients to the plant, which the plant cannot synthesize on its own.

    2. The plant provides carbohydrates to the fungi, while the fungi enhance the plant's nutrient absorption, particularly phosphorus and other minerals.

    3. The fungi protect the plant from harmful pathogens in the soil, while the plant provides nitrogen to the fungi.

    4. The association helps the plant by reducing its water uptake, allowing it to conserve energy in nutrient-poor conditions.

    5. The plant absorbs carbon dioxide released by the fungi, which enhances photosynthesis in low-nutrient soils.

35. What event marked the end of the Archean Eon and resulted in the extinction of many prokaryotic groups?

    1. The Permian mass extinction

    2. The formation of stromatolites

    3. The Cambrian explosion

    4. The Great Oxygenation Event

    5. The Cretaceous mass extinction

36. Which statement best describes the process of serial endosymbiosis in the evolution of eukaryotic cells?

    1. Plastids evolved before mitochondria through endosymbiosis with aerobic prokaryotes.

    2. Ancestral prokaryotes gradually developed endomembranes that evolved to become mitochondria and plastids.

    3. The sequential incorporation of prokaryotic endosymbiont cells led to the formation of mitochondria and plastids.

    4. Mitochondria evolved from plastids through a series of endosymbiotic events.

    5. Cyanobacteria evolved from archaeal ancestors through endosymbiosis with eukaryotic cells.

37. Which of the following correctly describes the difference between primary and secondary endosymbiosis?

    1. Primary endosymbiosis involved the engulfment of a prokaryote, while secondary endosymbiosis involved an early eukaryote engulfing another eukaryote that had already undergone endosymbiosis.

    2. Primary endosymbiosis leads to three membranes around the engulfed organelle, whereas secondary endosymbiosis results in two membranes.

    3. Primary endosymbiosis occurred in plants, while secondary endosymbiosis occurred in animals only.

    4. Secondary endosymbiosis led to the evolution of mitochondria, while primary endosymbiosis led to chloroplasts.

    5. Secondary endosymbiosis happens exclusively in prokaryotic cells.

38. The role of secondary (2°) endosymbiosis in the diversification of protists involves:

    1. Prokaryotic cells engulfing eukaryotic cells

    2. Eukaryotic cells engulfing prokaryotic cells

    3. Eukaryotic cells engulfing other eukaryotic cells

    4. Prokaryotic cells dividing by binary fission

    5. Eukaryotic cells undergoing mitosis

39. Which of the following scenarios best explains how secondary endosymbiosis has affected protist diversity?

    1. Protists that have undergone secondary endosymbiosis are less metabolically flexible, limiting their ability to adapt to changing environments.

    2. Secondary endosymbiosis allowed for the acquisition of plastids, enabling protists to adapt to both autotrophic and heterotrophic lifestyles.

    3. Secondary endosymbiosis prevents protists from obtaining energy independently, limiting diversity.

    4. Secondary endosymbiosis forced all protists to rely solely on photosynthesis.

    5. Secondary endosymbiosis only allowed protists to thrive in nutrient-poor environments.

40. How many of the following protist groups include amoebas, protists that move and feed by pseudopodia?
    1. Rhizarians; 2. Apicomplexans; 3. Tubulinids; 4. Slime moulds; 5. Euglenozoans.

    1. 2

    2. 3

    3. 1

    4. 5

    5. 4

41. Which of the following accurately reflects the ecological and functional diversity within the SAR clade?

    1. Contains only photosynthetic organisms that contribute to marine phytoplankton.

    2. Primarily includes organisms with threadlike pseudopodia, like Radiolarians.

    3. Consists exclusively of parasitic protists that affect marine life.

    4. Contains organisms that evolved directly from plants.

    5. Includes protists with both photosynthetic and heterotrophic lifestyles, such as diatoms, brown algae, and ciliates.

42. Which of the following best describes the evolutionary relationship between charophytes and plants?

    1. Plants evolved directly from charophytes.

    2. Charophytes evolved directly from plants.

    3. Charophytes and plants share a common ancestor.

    4. Charophytes and plants evolved independently.

    5. Plants evolved from marine algae.

43. The evolution of vascular tissue in plants was a critical adaptation for terrestrial life. How did this adaptation help plants colonize land?

    1. It increased water absorption from the soil

    2. It enabled plants to grow taller and transport nutrients and water against gravity

    3. It allowed plants to conduct photosynthesis more efficiently

    4. It protected plants from herbivory on land

    5. It allowed for more efficient reproduction in terrestrial environments

44. What is the main function of sporopollenin in plants?

    1. Nutrient absorption

    2. Gas exchange

    3. Water transport

    4. Protection from desiccation and physical stresses

    5. Structural support

45. Why is the bryophyte life cycle considered unique compared to other plants, particularly in the way the sporophyte and gametophyte stages interact?

    1. The gametophyte grows on the sporophyte and provides it with nutrients

    2. The sporophyte is the dominant and independent generation in bryophytes

    3. The sporophyte remains permanently attached to the gametophyte for its entire life

    4. Bryophyte gametophytes produce seeds rather than spores

    5. Bryophytes have eliminated the need for a sporophyte stage altogether

46. How does the requirement for water during fertilization in both charophytes and bryophytes limit their reproductive success compared to seed plants?

    1. It restricts their habitat to areas where water is abundant

    2. It allows them to reproduce only in specific seasons

    3. It forces them to develop aquatic adaptations

    4. It limits their ability to disperse gametes via wind

    5. It reduces their efficiency in nutrient absorption

47. Which of the following best differentiates the life cycle of non-vascular plants from that of seedless vascular plants?

    1. Non-vascular plants disperse via spores.

    2. Non-vascular plants have a dominant gametophyte generation.

    3. Non-vascular plants have independent gametophyte and sporophyte generations.

    4. Non-vascular plants have dominant sporophyte generations, while seedless vascular plants have dominant gametophyte generations.

    5. The life cycle of non-vascular plants involves alternation of generations between a dominant sporophyte and a reduced gametophyte.

48. Which of the following statements is true regarding the life cycle of seedless vascular plants?

    1. Sporophytes rely continuously on gametophytes.

    2. Sporophytes are tiny, independent plants.

    3. Gametophytes are dominant and long-living.

    4. Sporophytes lack true roots and leaves.

    5. Gametophytes produce flagellated sperm.

49. If a fern gametophyte has both male and female gametangia on the same plant, then it ____________________.

    1. No longer has a functional sporophyte generation.

    2. Must be diploid.

    3. Has antheridia and archegonia combined into a single sex organ.

    4. Belongs to a species that is homosporous.

    5. Is not a fern, because fern gametophytes are always either male or female.

50. Ferns reproduce through the production of spores in specialized structures called sporangia, typically found on the underside of their fronds. How does the location of sporangia contribute to the success of spore dispersal in ferns?

    1. Sporangia produce seeds that are dispersed by animals

    2. The elevated position of sporangia on fronds allows spores to be released and carried by wind

    3. Sporangia absorb water from the surrounding environment to help spores develop

    4. Sporangia protect spores from desiccation during dry periods

    5. Sporangia aid in nutrient absorption for spore growth

51. In seed plants, the gametophytes are:

    1. Larger than the sporophyte

    2. Independent of the sporophyte

    3. Microscopic and dependent on the sporophyte

    4. The primary stage of the life cycle

    5. Non-existent

52. How does pollen facilitate fertilization in seed plants?

    1. By forming an outer coat of sporopollenin

    2. By releasing sperm into the environment

    3. By providing nutrients to the female gametophyte

    4. By protecting the male gametophyte during dispersal

    5. By producing seeds after pollination

53. One evolutionary benefit of seed dispersal over spore dispersal is:

    1. Seeds are smaller and travel further

    2. Seeds contain a food supply for the embryo

    3. Seeds require water for dispersal

    4. Spores contain more genetic material than seeds

    5. Spores offer better protection to the embryo

54. During the conifer life cycle, what critical role does the pollen tube play in reproduction?

    1. Allows the male gametophyte to reach the female gametophyte for fertilization without requiring water

    2. Facilitates the dispersal of male gametes by water

    3. Acts as a transport mechanism for female gametes

    4. Ensures the seeds are dispersed by wind

    5. Protects the developing embryo after fertilization

55. Among legume plants (peas, beans, etc.), the seeds are contained in a fruit that is commonly known as a pod. Upon opening these pods, it is common to observe that some ovules have become mature seeds, whereas other ovules have not. Thus, which of the following statements is (are) true?
    1. The flowers that gave rise to such pods were not pollinated
    2. Pollen tubes did not enter all of the ovules in such pods
    3. There was not enough endosperm to distribute to all of the ovules in such pods
    4. The ovules that failed to develop into seeds were derived from sterile floral parts
    5. Fruit can develop, even if all ovules within have not been fertilized

    1. 1 and 5

    2. 1 only

    3. 2 and 5

    4. 2 and 4

    5. 3 and 5

56. What is the primary significance of dikaryotic stages in the fungal life cycle, particularly for Ascomycota and Basidiomycota?

    1. The dikaryotic stage enables the fungi to undergo asexual reproduction within the fruiting body, enhancing spore production efficiency.

    2. The dikaryotic phase delays karyogamy, allowing fungi to develop complex fruiting bodies where numerous karyogamy and meiosis events can occur, resulting in a high diversity of sexual spores.

    3. The dikaryotic state provides a backup nucleus in each cell, enabling fungi to repair genetic damage without additional reproductive stages.

    4. Dikaryotic mycelia are resistant to environmental stress, which allows fungi to conserve energy by slowing growth until conditions are favorable for spore dispersal.

    5. The dikaryotic stage enables immediate genetic recombination and spore release, promoting rapid population growth in diverse environments.

57. Many basidiomycete fungi disperse via the production of millions of basidiospores. How many of the following traits directly support prolific basidiospore production?
    1. Asexual production of basidiospores
    2. Long-lived dikaryotic mycelium
    3. Basidiocarps lined with basidia
    4. Fragmentation of the mycelium
    5. Absorptive nutrition
    6. Meiosis of basidiospores after dispersal

    1. 3

    2. 6

    3. 5

    4. 4

    5. 2

58. Mixotrophy, the ability to obtain energy and carbon through both autotrophic and heterotrophic means, is widespread among protists. What is the most likely explanation for the evolutionary origin of mixotrophy in eukaryotic lineages?

    1. Mixotrophy evolved independently multiple times through endosymbiotic events that introduced photosynthetic capabilities to heterotrophic ancestors.

    2. Mixotrophy originated once in early eukaryotes and was later lost in some lineages, resulting in purely autotrophic or heterotrophic organisms.

    3. Mixotrophy is a short-lived state that occurs only under environmental stress before organisms revert to obligate autotrophy or heterotrophy.

    4. Mixotrophic protists evolved from fungal ancestors that later acquired photosynthetic plastids through horizontal gene transfer.

    5. The presence of mixotrophy in diverse protist groups suggests it was inherited from the last eukaryotic common ancestor.

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