Unity and diversity
Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.
Preview questions (no answers)
- 1.
Which functional group is found at the 3' end of a DNA strand?
A.Hydroxyl group
B.Phosphate group
C.Amine group
D.Carbonyl group
- 2.
Which functional group is found at the 5' end of a DNA strand?
A.Hydroxyl group
B.Phosphate group
C.Carboxyl group
D.Methyl group
- 3.
The sequence of bases in DNA determines the sequence of:
A.Sugars in the backbone
B.Amino acids in a protein
C.Phosphates in the nucleus
D.Lipids in the membrane
- 4.
What kind of bond is a hydrogen bond in the context of DNA?
A.A strong covalent bond
B.A weak attraction between polar parts of bases
C.A bond involving the sharing of electrons
D.An attraction between oppositely charged ions
- 5.
A double-stranded DNA molecule is 50 base pairs long. If 20% of the nitrogenous bases in this molecule are Cytosine, what is the total number of hydrogen bonds holding the two strands together?
A.100
B.110
C.120
D.140
- 6.
If a DNA molecule contains 30% Adenine, what is the total percentage of pyrimidines in the molecule?
A.30%
B.20%
C.50%
D.70%
- 7.
What describes the 'double helix'?
A.Two strands of DNA coiled around each other
B.A single strand of DNA coiled into a circle
C.Two strands of RNA paired with one strand of DNA
D.A protein wrapped around a DNA molecule
- 8.
A culture of E. coli was grown for many generations in a medium containing the heavy isotope of nitrogen () until all its DNA was fully labeled. The bacteria were then transferred to a medium containing the light isotope () and allowed to replicate. The flowchart below shows the progression of DNA density over the first two generations. If the bacteria undergo a third round of replication (Generation 3), what is the predicted ratio of hybrid-density () DNA molecules to light-density () DNA molecules?
A.B.C.D. - 9.
During DNA replication, what provides the energy for the formation of the new phosphodiester bond?
A.ATP hydrolysis by helicase
B.The release of two phosphate groups from the incoming deoxynucleoside triphosphate
C.The kinetic energy of the ribosome
D.Heat energy from the surrounding cytoplasm
- 10.
The diagram below represents a nucleic acid polymer. Which feature identifies this as RNA rather than DNA?
A.Presence of a phosphate group
B.Presence of a group on the sugar
C.The phosphodiester bond
D.The to directionality
Download the worksheet for Unity and diversity - Nucleic acids to practice offline. It includes additional chapter-level practice questions.
Cell structure
SubtopicCell structure under Unity and diversity for Grade 12 IB.
Preview questions (no answers)
- 1.
Which of these is a function of the cytoplasm?
A.Holding the organelles in place and site of many metabolic reactions
B.Acting as the brain of the cell
C.Preventing water from entering the cell
D.Packaging proteins for export
- 2.
Which of the following is NOT a kingdom belonging to the Eukaryota domain?
A.Animalia
B.Plantae
C.Fungi
D.Archaea
- 3.
Which theory explains the origin of mitochondria and chloroplasts?
A.The Cell Theory
B.The Endosymbiotic Theory
C.The Theory of Evolution
D.The Spontaneous Generation Theory
- 4.
In the provided comparison, which structure is unique to prokaryotes?
A.Cytoplasm
B.Plasma membrane
C.70S Ribosomes
D.DNA
- 5.
Leukemia is a disease characterized by the production of large numbers of abnormal white blood cells. One common treatment involves the use of hematopoietic stem cells. The flowchart below outlines the main stages of this therapeutic process. Which statement correctly describes the nature of the stem cells used in this treatment?
A.They are totipotent cells that have the potential to develop into an entire new organism.
B.They are specialized white blood cells that have been cloned in a laboratory setting.
C.They are multipotent cells that can differentiate into various types of healthy blood cells.
D.They are pluripotent cells that are typically harvested from the patient's nervous system.
- 6.
What limits the maximum size of a cell?
A.The size of the nucleus
B.The availability of nutrients in the environment
C.The rate at which substances can diffuse across the membrane
D.The number of ribosomes available for protein synthesis
- 7.
What is the role of vesicles in a cell?
A.To replicate DNA
B.To transport materials between organelles
C.To provide structural support
D.To catalyze metabolic reactions
- 8.
The diagram illustrates the hypothesized origin of mitochondria through the process of endosymbiosis. Based on the mechanics of the engulfment phase shown, which statement correctly explains the origin and nature of the two membranes surrounding a modern mitochondrion?
A.The inner membrane was originally the prokaryote's plasma membrane, while the outer membrane was derived from the host cell's vesicle.
B.Both the inner and outer membranes were synthesized by the host cell's Rough Endoplasmic Reticulum after the bacterium was absorbed.
C.The outer membrane represents the original bacterial cell wall, and the inner membrane is the host cell's modified plasma membrane.
D.The inner membrane was formed by the fusion of bacterial ribosomes, while the outer membrane is a lipid bilayer unique to eukaryotes.
- 9.
The diagram below models two different cell structures. Cell 1 represents a simple cell where all metabolic reactions occur in the cytoplasm or at the plasma membrane. Cell 2 represents a larger cell that has evolved an internal membrane system, labeled 'X'. How does the evolution of the structure labeled 'X' specifically address the physical limitations imposed by the Surface Area to Volume (SA:V) ratio as a cell increases in size?
A.By increasing the total volume of the cytoplasm to allow for a greater variety of biochemical pathways.
B.By decreasing the distance that oxygen and nutrients must travel to reach the center of the cell.
C.By providing additional surface area for membrane-bound enzymes to function without significantly increasing the cell's total volume.
D.By insulating the cell against temperature fluctuations caused by a decrease in the rate of diffusion.
- 10.
A student views a sample of human cheek cells under a light microscope. Which of the following would NOT be visible?
A.Nucleus
B.Plasma membrane
C.Cytoplasm
D.80S Ribosome
Download the worksheet for Unity and diversity - Cell structure to practice offline. It includes additional chapter-level practice questions.
Diversity of organisms
SubtopicDiversity of organisms under Unity and diversity for Grade 12 IB.
Preview questions (no answers)
- 1.
Which of these is a feature of the phylum Angiospermophyta?
A.Production of cones
B.Absence of vascular tissue
C.Production of flowers
D.Reproduction via spores only
- 2.
What does 'divergence' refer to in a cladogram?
A.When two species become extinct at the same time
B.When a population becomes more similar over time
C.The point where one lineage splits into two
D.The movement of a species to a new island
- 3.
Which of the following are the three domains of life?
A.Plantae, Animalia, Fungi
B.Bacteria, Archaea, Eukaryota
C.Prokaryota, Eukaryota, Protoctista
D.Monera, Protista, Eukarya
- 4.
Which group is a clade?
A.A group of birds that all have blue feathers but different ancestors
B.An ancestor and all of its descendants
C.All organisms living in a tropical rainforest
D.All animals that can fly, including insects and bats
- 5.
Recent advancements in DNA sequencing have led to the reclassification of many organisms. Based on the cladogram below, what is the most likely reason Species L was recently reclassified into a group with Species M rather than staying in a group with Species K?
A.Species L and K were found to have more homologous anatomical structures than L and M.
B.Species L and M both evolved similar traits independently through convergent evolution.
C.DNA analysis revealed that L and M share a more recent common ancestor at Node 1 than L and K.
D.The rate of mutation in the ribosomal RNA of Species K is significantly higher than in Species L.
- 6.
A specimen of an unknown plant is observed to have roots, woody stems, and seeds that are not enclosed within a fruit. Based on the provided flowchart, which label represents the phylum to which this plant belongs?
A.Phylum 1
B.Phylum 3
C.Phylum 2
D.Phylum 4
- 7.
Which of the following is NOT one of the criteria used by the International Botanical Congress (IBC) for naming plants?
A.Names must be in Latin or treated as Latin
B.No two species can have the same name
C.The name must be based on the color of the flower
D.The genus name must start with an uppercase letter
- 8.
What provides the strongest evidence that birds are a clade within the group traditionally known as reptiles?
A.Both groups are ectothermic.
B.Both groups have scales (birds on their legs) and lay amniotic eggs.
C.Birds and reptiles both have four-chambered hearts.
D.Fossil records show birds evolved from amphibians independently.
- 9.
Which of the following is the most significant difference between the cell membranes of Archaea and those of Bacteria and Eukaryota?
A.Archaea membranes contain cholesterol, whereas others contain ergosterol.
B.Archaea membranes use ether-linked lipids rather than ester-linked lipids.
C.Archaea membranes lack proteins entirely.
D.Archaea membranes are only found in extreme environments.
- 10.
A plant produces flowers and fruits. Inside the fruit are seeds. Which phylum does it belong to?
A.Bryophyta
B.Filicinophyta
C.Coniferophyta
D.Angiospermophyta
Download the worksheet for Unity and diversity - Diversity of organisms to practice offline. It includes additional chapter-level practice questions.
Evolution and speciation
SubtopicEvolution and speciation under Unity and diversity for Grade 12 IB.
Preview questions (no answers)
- 1.
What happens to the number of offspring in a population where resources are very scarce?
A.Most offspring will survive and reproduce
B.Only a small proportion of offspring will survive to reproduce
C.All offspring will survive because of adaptation
D.The population will stop producing offspring immediately
- 2.
Why is genetic variation important for the survival of a species?
A.It allows the species to occupy only one niche
B.It ensures some individuals may survive if environmental conditions change
C.It prevents any mutations from occurring in the future
D.It makes all individuals identical and stronger
- 3.
Charles Darwin is most famous for proposing which mechanism for evolution?
A.Inheritance of acquired characteristics
B.Natural selection
C.Genetic engineering
D.Endosymbiosis
- 4.
What is the term for a permanent change in the DNA sequence of a gene?
A.Adaptation
B.Mutation
C.Selection
D.Variation
- 5.
The flowchart below represents a sequence of events in a population of rabbits. Based on this information, what is the most likely long-term effect on the population's gene pool?
A.The population will become extinct because the slow foragers cannot find any food.
B.The alleles for fast foraging will increase in frequency over successive generations.
C.All rabbits will eventually develop the same foraging speed due to the limited food supply.
D.The rabbits will stop competing and begin to share resources to ensure survival.
- 6.
The diagram illustrates the process of selective breeding in dogs. How does this process provide evidence for the theory of evolution?
A.It shows that the genetic makeup of a population can be altered over many generations by selection.
B.It demonstrates that mutations only occur when humans intervene in the breeding process.
C.It proves that individual organisms can adapt their traits within their own lifetime to suit human needs.
D.It confirms that all traits are acquired through use and disuse during an organism's life.
- 7.
Evidence for evolution includes the fact that all living organisms use the same genetic code. This suggests that:
A.Evolution is not occurring currently
B.All life shares a common evolutionary origin
C.The genetic code is determined by the environment
D.Mutations cannot change the genetic code
- 8.
What is the primary difference between 'allopatric' and 'sympatric' speciation?
A.Allopatric involves geographic isolation; sympatric occurs in the same geographic area.
B.Allopatric occurs quickly; sympatric occurs slowly over millions of years.
C.Allopatric only occurs in animals; sympatric only occurs in plants.
D.Allopatric requires natural selection; sympatric requires only genetic drift.
- 9.
During a period of rapid environmental change, which population would likely have the highest probability of survival?
A.A large population with low genetic diversity.
B.A small population with high genetic diversity.
C.A large population with high genetic diversity.
D.A population that reproduces asexually and has a fast generation time.
- 10.
Why are analogous structures NOT used to determine evolutionary relationships in cladistics?
A.They are too difficult to identify in the fossil record.
B.They represent shared ancestry but have been modified too much.
C.They are the result of similar selective pressures rather than a common ancestor.
D.They only occur in plants and not in animals.
Download the worksheet for Unity and diversity - Evolution and speciation to practice offline. It includes additional chapter-level practice questions.
Conservation of biodiversity
SubtopicConservation of biodiversity under Unity and diversity for Grade 12 IB.
Preview questions (no answers)
- 1.
Why is the participation of local communities essential for successful conservation?
A.Locals are the only people allowed to see the animals
B.Conservation is more effective when people living nearby support and benefit from it
C.Local people can hunt all the animals
D.Local communities do not have any impact on biodiversity
- 2.
Which of the following species would be most likely to go extinct first in a shrinking habitat?
A.A species with a very wide diet
B.A species with a very specific niche and small population
C.A species that reproduces very quickly
D.An invasive species
- 3.
What is the main cause of the loss of 'ecosystem diversity'?
A.Evolution of new species
B.Habitat destruction and land-use change
C.Increase in rainfall
D.Migration of animals
- 4.
Which of the following describes a 'nature reserve'?
A.A city park with playground equipment
B.A protected area of land managed to preserve its flora and fauna
C.A laboratory where plants are cloned
D.A warehouse where animal skins are kept
- 5.
If you are calculating Simpson's Index for two fields, Field 1 () and Field 2 (), which field would likely be more resilient to a disease affecting one specific plant species?
A.Field 1, because high diversity usually means other species can maintain ecosystem function.
B.Field 2, because fewer species means there is less chance of the disease spreading.
C.Field 2, because the dominant species is likely to be resistant.
D.Both fields will be equally affected regardless of diversity.
- 6.
Sustainable development aims to balance human needs with biodiversity conservation. Which is a sustainable practice?
A.Clear-cutting forests for short-term timber profits.
B.Selective logging that allows the forest canopy to remain largely intact.
C.Using high-drift nets that catch all marine life in an area.
D.Converting all natural grasslands into monoculture wheat fields.
- 7.
Which of the following is a direct consequence of a 'population bottleneck'?
A.Increased resistance to disease.
B.A significant reduction in the genetic diversity of the survivors.
C.An immediate increase in the birth rate.
D.Expansion of the species' niche.
- 8.
Which organization is responsible for maintaining the 'Red List' of threatened species?
A.UNESCO
B.WWF
C.IUCN
D.CITES
- 9.
If a species' population falls below its 'Minimum Viable Population' (MVP) size, what is the most likely outcome?
A.The species will immediately evolve new traits to survive.
B.The population will become more stable because there is less competition.
C.The population is likely to spiral toward extinction due to inbreeding and environmental fluctuations.
D.The species will move to a new habitat where it can be more successful.
- 10.
Why is the conservation of 'Hotspots' (areas with high levels of endemic species and significant habitat loss) a common strategy?
A.These areas are always the easiest to protect legally.
B.Focusing on hotspots allows for the protection of the greatest number of species per unit of effort.
C.Hotspots are areas where no humans live, so there is no conflict.
D.Hotspots are the only places on Earth where new species are still evolving.
Download the worksheet for Unity and diversity - Conservation of biodiversity to practice offline. It includes additional chapter-level practice questions.