IB Biology Quiz: Apply Diversity Of Organisms
19 questions · exam conditions
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Apply Diversity Of OrganismsQuestion 1 of 19

The forelimb of a whale (a flipper) and the forelimb of a human (an arm) have a similar underlying bone structure, despite their different functions. In contrast, the wing of a bee and the wing of a bird serve the same function but have very different structures. Which statement correctly applies these concepts to natural classification?

The bee and bird should be classified closely together because their wings are analogous structures.
Analogous structures are the primary evidence used for constructing natural classifications.
Homologous structures like the whale flipper and human arm are not useful for establishing evolutionary relationships.
The whale and human are classified as mammals because their forelimbs are homologous structures, indicating a shared ancestor.
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IB Biology Quiz

IB Biology Quiz: Apply Diversity Of Organisms

Practice Apply Diversity Of Organisms in IB Biology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

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This quiz focuses on Apply Diversity Of Organisms, giving you a quick way to practice the rules, question types, and explanations that matter most for IB Biology.

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Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

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Question 1

The forelimb of a whale (a flipper) and the forelimb of a human (an arm) have a similar underlying bone structure, despite their different functions. In contrast, the wing of a bee and the wing of a bird serve the same function but have very different structures. Which statement correctly applies these concepts to natural classification?

  1. The bee and bird should be classified closely together because their wings are analogous structures.
  2. Analogous structures are the primary evidence used for constructing natural classifications.
  3. Homologous structures like the whale flipper and human arm are not useful for establishing evolutionary relationships.
  4. The whale and human are classified as mammals because their forelimbs are homologous structures, indicating a shared ancestor. (correct answer)
Explanation: The correct answer is B. Natural classification is based on evolutionary relationships, which are revealed by homologous structures. The similar bone structure in the whale flipper and human arm, despite different functions, is evidence of a shared mammalian ancestor. These are homologous. Bee and bird wings are analogous (same function, different origin) and do not indicate a close evolutionary relationship. Therefore, A and D are incorrect. C is the opposite of the truth; homology is key evidence for phylogeny.

Question 2

A biologist is studying four species of insects: Apis mellifera, Apis cerana, Bombus terrestris, and Vespula vulgaris. Based on binomial nomenclature, which statement represents the most accurate conclusion about their evolutionary relationship?

  1. Apis mellifera and Apis cerana are the most closely related because they belong to the same genus. (correct answer)
  2. Apis mellifera and Bombus terrestris are more closely related than Apis mellifera and Vespula vulgaris.
  3. Bombus terrestris and Vespula vulgaris are not related as they are in different genera.
  4. All four species are equally related as they are all insects in the order Hymenoptera.
Explanation: The correct answer is A. Binomial nomenclature reflects the hierarchical system of classification. Organisms in the same genus (Apis) share a more recent common ancestor and are more closely related to each other than to organisms in different genera. B cannot be determined from the names alone; while Apis and Bombus are both bees (family Apidae) and Vespula is a wasp (family Vespidae), the names only definitively group the two Apis species. C is incorrect; being in different genera does not mean they are unrelated, just less closely related than members of the same genus. D is incorrect because while they are all in the same order, the genus level indicates a much closer relationship.

Question 3

Ecosystem X has 10 species with 100 individuals each. Ecosystem Y has 10 species, but one species has 910 individuals while the other nine species have 10 individuals each. Both ecosystems have a total of 1000 individuals and 10 species.

How does the biodiversity of Ecosystem X compare to Ecosystem Y?

  1. Ecosystem X has lower biodiversity because it lacks a dominant species.
  2. Ecosystem Y has higher biodiversity because it has the same number of species in a similar area.
  3. The biodiversity of both ecosystems is equal because they have the same species richness and total abundance.
  4. Ecosystem X has higher biodiversity because it has greater species evenness. (correct answer)
Explanation: The correct answer is D. Biodiversity has two main components: species richness (the number of species) and species evenness (the relative abundance of species). Both ecosystems have the same species richness (10 species). However, Ecosystem X has high species evenness, as all species have equal populations. Ecosystem Y has very low species evenness, as it is dominated by a single species. An ecosystem with greater species evenness is considered more diverse. Therefore, Ecosystem X has higher biodiversity.

Question 4

A taxonomist proposes grouping bats, birds, and insects together into a new taxon called 'Alata' (the winged ones). Another taxonomist argues against this grouping. What is the strongest argument against the 'Alata' taxon based on the principles of natural classification?

  1. The organisms live in different ecosystems and have different diets, making the grouping ecologically invalid.
  2. The ability to fly is an analogous trait that evolved independently in these groups, not from a recent common winged ancestor. (correct answer)
  3. Bats are mammals, birds are aves, and insects are arthropods, and these major taxa cannot be combined.
  4. The wings of bats, birds, and insects have different maximum airspeeds, indicating they are functionally distinct.
Explanation: The correct answer is B. Natural classification groups organisms based on shared ancestry (homology). The wings of bats, birds, and insects are examples of analogous structures; they serve the same function (flight) but evolved independently in different lineages. Grouping organisms based on an analogous trait creates an artificial, not a natural, classification. A is incorrect because ecological roles are not the primary basis for phylogenetic classification. C is a true statement about their current classification but doesn't explain why the proposed grouping is invalid from a phylogenetic perspective. D is incorrect because functional differences do not invalidate a homologous relationship if one existed.

Question 5

The taxonomic classification of two organisms, the gray wolf (Canis lupus) and the coyote (Canis latrans), is shown. They both belong to the Family Canidae, Order Carnivora, Class Mammalia, and Phylum Chordata. At which taxonomic level do they first diverge?

  1. Genus
  2. Family
  3. Species (correct answer)
  4. Order
Explanation: The correct answer is C. The binomial names show that both organisms belong to the genus Canis. The specific name (epithet) is different: lupus for the wolf and latrans for the coyote. Therefore, they are different species within the same genus. They diverge at the species level, which is the most specific level of classification listed. They share the same classification at all higher levels provided (Genus, Family, Order, etc.).

Question 6

Historically, fungi were classified in the Plant kingdom due to their immobility and possession of cell walls. Modern molecular evidence led to their reclassification into their own kingdom.

Which discovery was most significant in justifying the reclassification of fungi into a separate kingdom, distinct from plants?

  1. The composition of the fungal cell wall is primarily chitin, not cellulose as found in plants.
  2. Fungi are heterotrophic, absorbing nutrients from their environment, whereas plants are autotrophic.
  3. Analysis of ribosomal RNA sequences showed fungi share a more recent common ancestor with animals than with plants. (correct answer)
  4. Fungi reproduce using spores, a method that is fundamentally different from the seed production seen in most plants.
Explanation: The correct answer is C. While options A and B describe valid and important differences, the most powerful and definitive evidence for reclassification comes from molecular data that reveals evolutionary relationships (phylogeny). Ribosomal RNA sequence analysis demonstrated that fungi are more closely related to animals, justifying their placement in a completely separate kingdom. This represents a fundamental shift in understanding their evolutionary lineage, which is the basis for natural classification. A and B were known before the major reclassification and are supporting evidence, but the genetic data was decisive. D is incorrect as many plants also reproduce via spores (e.g., ferns and mosses).

Question 7

For a long time, red pandas (Ailurus fulgens) were classified in the same family as giant pandas, and sometimes with raccoons. Recent genetic studies have led to them being placed in their own unique family, Ailuridae. This change best illustrates which concept in science?

  1. Classification systems are fixed and based on unchanging morphological evidence.
  2. The binomial nomenclature for the red panda is incorrect and must be changed.
  3. Scientific knowledge is provisional, and classification systems are revised based on new evidence. (correct answer)
  4. Organisms are classified based on their dietary habits and geographical distribution.
Explanation: The correct answer is C. This scenario is a prime example of the Nature of Science (NOS) principle that scientific theories and classifications are not absolute but are subject to change in light of new, compelling evidence. The advent of molecular genetics provided a more accurate way to determine evolutionary relationships, leading to the revision of the red panda's classification. A is incorrect because this shows classification is not fixed. B is incorrect; the family-level change does not automatically invalidate the genus and species name. D is incorrect as phylogeny, not ecology, is the primary basis for modern classification.

Question 8

A conservation program aims to reintroduce a species of frog into a habitat from which it was wiped out by a fungal disease. To maximize the long-term survival of the new population, the program should prioritize reintroducing individuals:

  1. that are all from a single, large, healthy captive population.
  2. from several geographically distinct wild populations. (correct answer)
  3. that are exclusively the largest and strongest available.
  4. that were raised in a sterile, disease-free environment.
Explanation: The correct answer is B. Reintroducing individuals from several geographically distinct populations maximizes the genetic diversity of the new population. High genetic diversity increases the probability that some individuals will possess alleles conferring resistance to the fungal disease or other future environmental pressures, thus enhancing the long-term survival prospects of the population. A would result in low genetic diversity (a bottleneck). C would artificially select for size, potentially at the expense of other important traits like disease resistance. D is useful for ensuring the reintroduced animals are healthy, but it does not address the crucial issue of genetic diversity for long-term adaptation.

Question 9

A field biologist is assessing the biodiversity of a forest plot. They count the number of different tree species and the number of individuals of each species. Which two components of biodiversity are being directly measured?

  1. Genetic diversity and species richness
  2. Species evenness and ecosystem diversity
  3. Ecosystem diversity and genetic diversity
  4. Species richness and species evenness (correct answer)
Explanation: The correct answer is B. Counting the number of different tree species directly measures species richness. Counting the number of individuals of each species provides the data needed to calculate species evenness (the relative abundance of the different species). Genetic diversity would require DNA analysis, and ecosystem diversity would require comparing this forest plot to other ecosystems like grasslands or wetlands. The biologist's actions are focused solely on richness and evenness within one ecosystem.

Question 10

A scientist discovers a new unicellular organism in a hydrothermal vent. It has a cell wall but lacks peptidoglycan. Its plasma membrane lipids are joined by ether linkages, and its DNA is associated with histone-like proteins. To which domain should this organism be assigned?

  1. Bacteria, because it is unicellular and has a cell wall.
  2. Archaea, because it lives in an extreme environment and lacks peptidoglycan. (correct answer)
  3. Eukarya, because its DNA is associated with proteins similar to histones.
  4. Bacteria, because organisms in hydrothermal vents are always prokaryotic.
Explanation: The correct answer is B. The combination of features—extreme environment (hydrothermal vent), cell wall without peptidoglycan, ether-linked membrane lipids, and histone-like proteins—are all characteristic of the domain Archaea. Distractor A is incorrect because while many bacteria are unicellular with cell walls, the absence of peptidoglycan is a key differentiator. Distractor C is incorrect because while Eukarya have histones, they are multicellular or have membrane-bound organelles, and their membrane lipids are ester-linked. Distractor D is a plausible oversimplification; while prokaryotes thrive in such vents, the specific features point to Archaea, not Bacteria.

Question 11

The scientific name for the house cat is written as Felis catus. Which of the following represents an incorrect application of the conventions of binomial nomenclature?

  1. Felis Catus (correct answer)
  2. F. catus
  3. Felis catus
  4. Felis catus (underlined when handwritten)
Explanation: The correct answer is A. According to the rules of binomial nomenclature, the genus name (Felis) is capitalized, but the species name (specific epithet, catus) is always written in lowercase. Capitalizing the species name is a common error. Both names should be italicized in print or underlined when handwritten. Option B shows a correct abbreviation. Option C shows the correct full format. Option D describes the correct convention for handwriting.

Question 12

If two different species belong to the same family, what can be definitively concluded about their classification?

  1. They must also belong to the same genus.
  2. They must also belong to the same order. (correct answer)
  3. They must have evolved from different ancestors.
  4. They cannot be placed in the same kingdom.
Explanation: The correct answer is B. The Linnaean system of classification is hierarchical. If two organisms are in the same family, they must also be in the same higher-level taxa, which include order, class, phylum, and kingdom. A is incorrect because a family can contain multiple genera. C is incorrect because belonging to the same family implies they evolved from a common ancestor. D is incorrect because they must be in the same kingdom.

Question 13

What is the primary advantage of using the binomial nomenclature system over common names in scientific communication?

  1. Binomial names are universal and unambiguous, avoiding confusion caused by regional differences in common names. (correct answer)
  2. Binomial names are more descriptive of the organism's appearance than common names.
  3. Binomial names are easier for the general public to remember and use correctly.
  4. Binomial names reflect the organism's position in the local food web.
Explanation: The correct answer is B. The key advantage of binomial nomenclature is its universality and precision. A single species may have dozens of common names in different languages or even different regions, leading to confusion. The scientific name is unique to that species worldwide. A is often untrue; many scientific names are not descriptive. C is incorrect; scientific names are often perceived as more difficult than common names. D is incorrect; the name reflects evolutionary relationships, not ecological roles.

Question 14

A natural taxon, or clade, is considered monophyletic. What must be included for a group of species to be considered a valid clade?

  1. An ancestral species and all of its descendants. (correct answer)
  2. All species that share a specific morphological feature, such as wings or fins.
  3. All species within a specific geographical area.
  4. An ancestral species and some, but not all, of its descendants.
Explanation: The correct answer is B. This is the definition of a monophyletic group, which is the goal of natural classification (cladistics). A clade must include a common ancestor and all species that have descended from it. Option A describes an artificial group based on analogous traits. Option C describes an ecological or geographical grouping, not a phylogenetic one. Option D describes a paraphyletic group, which is not considered a valid clade in modern cladistics.

Question 15

A significant reduction in the diversity of decomposer fungi and bacteria in a forest ecosystem would most likely lead to which of the following consequences?

  1. A rapid increase in the population sizes of primary consumers.
  2. A decrease in the atmospheric concentration of carbon dioxide over the ecosystem.
  3. An accumulation of dead organic matter and a decrease in soil nutrient availability. (correct answer)
  4. An increase in the rate of photosynthesis by the producer organisms.
Explanation: The correct answer is C. Decomposers are essential for nutrient cycling. They break down dead organic material (detritus), releasing inorganic nutrients back into the soil where they can be taken up by producers. A loss of decomposer diversity would slow this process, leading to an accumulation of leaf litter and other dead material, and trapping essential nutrients, making them unavailable for plants. This directly links biodiversity to ecosystem function. A, B, and D are incorrect as the lack of nutrients would eventually limit plant growth (photosynthesis) and consequently the populations that depend on them.

Question 16

The Kingdom Protista is often referred to as a 'taxonomic grab bag' and is being re-evaluated by scientists. What is the most likely reason for this ongoing reclassification?

  1. Protists are all unicellular, and it is difficult to distinguish between unicellular species based on morphology alone.
  2. Genetic analysis has revealed that the organisms within Protista do not share a single common ancestor exclusive to the group. (correct answer)
  3. Many protists can switch between autotrophic and heterotrophic nutrition, making them difficult to place in a single kingdom.
  4. New species of protists are being discovered too rapidly to create a stable classification system.
Explanation: The correct answer is B. The Kingdom Protista is a paraphyletic group, meaning it contains a common ancestor but not all of its descendants (plants, animals, and fungi evolved from protist-like ancestors). Modern classification aims for monophyletic groups (a common ancestor and all its descendants). Genetic data has shown that the lineages within what was called Protista are incredibly diverse and do not form a single, coherent clade, leading to its dismantling into several new 'supergroups' or kingdoms.

Question 17

Which of the following provides the strongest evidence for assigning organisms to different domains?

  1. Differences in their method of reproduction (sexual vs. asexual).
  2. Differences in the sequences of nucleotides in ribosomal RNA. (correct answer)
  3. The presence or absence of a cell wall and its composition.
  4. The organism's mode of nutrition (autotrophic vs. heterotrophic).
Explanation: The correct answer is B. The three-domain system is based on fundamental molecular differences that indicate ancient evolutionary divergence. Ribosomal RNA (rRNA) genes are highly conserved and mutate slowly, making them ideal for comparing deep evolutionary relationships. Significant differences in rRNA sequences, as discovered by Carl Woese, were the primary evidence for establishing the domain Archaea as separate from Bacteria. While A, C, and D are important characteristics for classification at lower levels, they do not define the domains as effectively as molecular phylogeny.

Question 18

Which of the following organisms would be classified in the domain Eukarya?

  1. A unicellular organism with a cell wall of peptidoglycan and 70S ribosomes.
  2. A non-cellular infectious agent consisting of protein and nucleic acid.
  3. A unicellular organism found in a hypersaline lake with ether-linked membrane lipids.
  4. A multicellular organism that is photosynthetic and has cell walls made of cellulose. (correct answer)
Explanation: The correct answer is B. This describes a plant, which is a member of the domain Eukarya. Key features are multicellularity and photosynthesis within eukaryotic cells. A describes a typical bacterium (peptidoglycan wall, 70S ribosomes). C describes a typical archaeon (extremophile habitat, ether-linked lipids). D describes a virus, which is not classified within any of the three domains of life.

Question 19

Taxonomists have used morphology, biochemistry, and gene sequencing to classify organisms. Which statement best explains the relationship between these types of evidence?

  1. Morphological data is the most reliable as it is directly observable, while gene sequencing can be prone to errors.
  2. Gene sequence data is considered the most fundamental evidence as it reflects the genetic blueprint that dictates biochemistry and influences morphology. (correct answer)
  3. Biochemical evidence, such as protein structure, is now considered obsolete due to the precision of gene sequencing.
  4. All three types of evidence are equally weighted in modern classification, and a majority agreement determines the final placement.
Explanation: The correct answer is B. In modern phylogenetics, DNA and RNA sequences are considered the most direct and fundamental evidence of evolutionary relationships. An organism's genetic code (gene sequence) determines its proteins (biochemistry), which in turn direct the development and structure of the organism (morphology). Therefore, similarities in gene sequences are the strongest indicator of shared ancestry. A is incorrect because morphological similarities can be due to convergent evolution (analogy). C is incorrect because proteomics and other biochemical data are still very important and often corroborate genetic data. D is incorrect; while all evidence is considered, molecular data is typically given the greatest weight in resolving evolutionary relationships.