SBI3U · Unit 1 test review

Diversity of Living Things: Test Review

Everything for the Unit 1 test on one page: the key facts from all 7 lessons, the mistakes that cost the most marks, and a practice test that points you back to the lessons you need.

Key facts

Classification and Taxonomy

Ranks from broadest to most specific: domain, kingdom, phylum, class, order, family, genus, species.
Binomial name = Genus (capitalized) + specific epithet (lowercase), italicized or underlined: Homo sapiens.
Three domains: Bacteria and Archaea (prokaryotic) and Eukarya (eukaryotic). Archaea are more closely related to Eukarya than to Bacteria.
Six kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia.
The lower the rank two organisms share, the more closely related they are.
Cladograms group organisms by shared derived characteristics; each node is a common ancestor.

Dichotomous Keys and Field Sampling

A dichotomous key offers two contrasting choices at each step; a key for $n$ organisms needs $n - 1$ couplets.
Good couplets use observable, stable features, stated as true opposites.
Population density: $D = \frac{total counted}{total area sampled} .$
Estimated population: $N = D \times$ total habitat area.
Random placement and many replicate samples reduce bias and error.
Mark and recapture for mobile animals: $N = \frac{M \times C}{R}$ .

Prokaryotes, Eukaryotes and Viruses

Prokaryotes: no nucleus, circular DNA in a nucleoid, 70S ribosomes, binary fission. Eukaryotes: nucleus, linear chromosomes, 80S ribosomes, membrane-bound organelles.
Typical sizes: prokaryotes about 1–10 µm, eukaryotic cells about 10–100 µm, viruses about 20–300 nm (1 µm = 1000 nm).
A virus = DNA or RNA inside a protein capsid, sometimes with an envelope; it can reproduce only inside a host cell.
Lytic cycle: attachment, entry, replication, assembly, release (cell bursts).
Endosymbiotic theory: mitochondria came from engulfed aerobic bacteria and chloroplasts from engulfed photosynthetic bacteria (cyanobacteria).
Evidence: both organelles have circular DNA, 70S-type ribosomes, double membranes and divide like bacteria.

Protists and Fungi

Protists are eukaryotes that are not fungi, plants or animals; they are grouped informally as animal-like, plant-like or fungus-like by how they get food.
Amoeba moves and feeds with pseudopods, Paramecium with cilia, and Euglena with a flagellum; freshwater protists use contractile vacuoles to expel excess water.
Most protists reproduce asexually by binary fission; Paramecium can exchange genetic material by conjugation, which adds variation without making new cells.
Fungi are built of chitin-walled hyphae forming a mycelium, digest food outside their bodies and absorb it, and spread by spores.
Zygomycetes make zygosporangia, ascomycetes make spores in asci, and basidiomycetes make spores on basidia.
Fungi are key decomposers and form lichens (with algae) and mycorrhizae (with plant roots); some cause disease and Penicillium gave us penicillin.

From Algae to Flowers: Plant Diversity and Evolution

Land plants evolved from freshwater green algae; both share chlorophyll a and b, cellulose walls and starch storage.
Key adaptations to land: cuticle (water loss), stomata (gas exchange), vascular tissue (transport and support), pollen and seeds (reproduction without water), flowers and fruits (pollination and dispersal).
Alternation of generations: sporophyte (2n) → meiosis → spores (n) → gametophyte (n) → mitosis → gametes (n) → fertilization → zygote (2n) → sporophyte.
The gametophyte dominates in bryophytes; the sporophyte dominates in ferns, gymnosperms and angiosperms.
Order of appearance: bryophytes → seedless vascular plants (ferns) → gymnosperms → angiosperms.
Monocots: one cotyledon, parallel veins, parts in threes. Dicots: two cotyledons, net veins, parts in fours or fives.

The Animal Kingdom: Invertebrates to Vertebrates

Animals are multicellular heterotrophs that ingest food, lack cell walls and are motile at some stage.
Symmetry: asymmetrical (sponges), radial (cnidarians, adult echinoderms) or bilateral (most animals, with cephalization).
Tissue layers: none (sponges), two (cnidarians) or three, with mesoderm (all other phyla).
Body cavity: acoelomate (flatworms), pseudocoelomate (roundworms) or coelomate (annelids, molluscs, arthropods, echinoderms, chordates).
Chordates have a notochord, dorsal hollow nerve cord, pharyngeal slits and post-anal tail at some stage of life.
Vertebrate classes: fish, amphibians, reptiles, birds, mammals; birds and mammals are endotherms with four-chambered hearts.

Biodiversity and Human Impact

Three levels of biodiversity: genetic (alleles within a species), species (richness and evenness), ecosystem (variety of ecosystems).
Simpson's index of diversity: $D = 1 - \frac{\sum n ( n - 1 )}{N ( N - 1 )}$ ; closer to 1 means more diverse.
Biodiversity increases resilience through functional redundancy, complex food webs and genetic variation.
Major threats: habitat loss, invasive species, overharvesting, pollution, monoculture and climate change.
Genetically uniform populations, such as monocultures, can be wiped out by a single disease.

Where marks get lost

Capitalizing the specific epithet (writing Homo Sapiens) or forgetting to italicize or underline the name. Only the genus is capitalized. (Classification and Taxonomy)
Deciding relatedness by counting how many ranks are listed instead of finding the lowest shared rank. Two organisms in the same genus are closer relatives than two that only share a class. (Classification and Taxonomy)
Thinking Archaea are just a kind of bacteria because both are prokaryotes. Archaea differ in cell walls, membranes and genetic machinery, and they are more closely related to eukaryotes. (Classification and Taxonomy)
Reading a cladogram left to right as a timeline of which organism is "more evolved". Every living organism at a branch tip has been evolving for the same length of time; the diagram shows only the order in which lineages split. (Classification and Taxonomy)
Putting fungi in the plant kingdom because mushrooms grow in soil and do not move. Fungi cannot photosynthesize and have chitin walls, not cellulose. (Classification and Taxonomy)
Dividing the total count by the number of quadrats instead of by the total area. This only works when each quadrat is exactly 1 m²; a 0.25 m² quadrat needs the area in the calculation. (Dichotomous Keys and Field Sampling)
Forgetting to convert quadrat dimensions to square metres. A 50 cm frame is 0.25 m², not 50 m² or 2500 m². (Dichotomous Keys and Field Sampling)
Writing couplets that are not true opposites, such as "has wings" versus "is brown", so an organism could fit both choices or neither. (Dichotomous Keys and Field Sampling)
Using features that change with age, season or opinion ("large", "green", "has flowers") so the key fails for young organisms or in winter. (Dichotomous Keys and Field Sampling)
Placing quadrats where the organism is obviously common. This biases the estimate upward; placement must be random. (Dichotomous Keys and Field Sampling)
Saying prokaryotes have no DNA or no ribosomes. They have both; the DNA is simply not enclosed in a nucleus, and the ribosomes are the smaller 70S type. (Prokaryotes, Eukaryotes and Viruses)
Mixing up micrometres and nanometres when comparing sizes. 1 µm = 1000 nm, so a 2 µm bacterium is 2000 nm, not 2 nm. (Prokaryotes, Eukaryotes and Viruses)
Thinking antibiotics can cure viral infections. Antibiotics attack bacterial structures such as cell walls and 70S ribosomes, which viruses do not have. (Prokaryotes, Eukaryotes and Viruses)
Stating that a virus contains both DNA and RNA. Each kind of virus uses one or the other as its genetic material. (Prokaryotes, Eukaryotes and Viruses)
Assuming all archaea live in extreme environments. Many do, but archaea are also common in soil, oceans and animal guts; the defining differences are molecular. (Prokaryotes, Eukaryotes and Viruses)
Calling a mushroom "the fungus". The mushroom is only the fruiting body; most of the organism is the hidden mycelium of hyphae. (Protists and Fungi)
Classifying fungi as plants because they grow in soil and do not move. Fungi have chitin walls, no chloroplasts, and absorb their food. (Protists and Fungi)
Thinking conjugation in Paramecium is reproduction. It exchanges genetic material between two cells but makes no new cells; binary fission makes the new cells. (Protists and Fungi)
Assuming slime moulds and water moulds are fungi because of their names. They are fungus-like protists without chitin walls. (Protists and Fungi)
Saying fungi digest food inside their bodies like animals. Fungi release enzymes outward, digest food outside the hyphae, and then absorb the small molecules. (Protists and Fungi)
Saying spores and gametes are the same thing. A spore grows into a new multicellular organism on its own; a gamete must fuse with another gamete. (From Algae to Flowers: Plant Diversity and Evolution)
Thinking gametes in plants are made by meiosis, as in animals. In plants, meiosis makes spores; the haploid gametophyte then makes gametes by mitosis. (From Algae to Flowers: Plant Diversity and Evolution)
Calling the green leafy moss plant the sporophyte. In mosses the green plant is the gametophyte; the sporophyte is the stalk and capsule on top. (From Algae to Flowers: Plant Diversity and Evolution)
Believing gymnosperms have flowers because they make seeds. Gymnosperm seeds sit exposed on cones; only angiosperms have flowers and fruits. (From Algae to Flowers: Plant Diversity and Evolution)
Reading the plant groups as a ladder in which mosses are "less evolved". Mosses are well adapted to their own habitats and have been evolving just as long as flowering plants. (From Algae to Flowers: Plant Diversity and Evolution)
Calling jellyfish or sea stars fish. Jellyfish are cnidarians and sea stars are echinoderms; neither has a backbone. (The Animal Kingdom: Invertebrates to Vertebrates)
Confusing the coelom with the gut. The gut is the digestive tube; the coelom is the fluid-filled cavity around the gut, lined by mesoderm. (The Animal Kingdom: Invertebrates to Vertebrates)
Assuming echinoderms are closely related to cnidarians because both are radial as adults. Echinoderm larvae are bilateral, and their development links them to chordates. (The Animal Kingdom: Invertebrates to Vertebrates)
Thinking "chordate" and "vertebrate" mean the same thing. All vertebrates are chordates, but lancelets and tunicates are chordates without backbones. (The Animal Kingdom: Invertebrates to Vertebrates)
Listing spiders and crabs as insects. They are arthropods, but insects are only the class with three body sections and six legs. (The Animal Kingdom: Invertebrates to Vertebrates)
Treating species richness and species diversity as the same thing. Diversity also depends on evenness: four species split evenly is more diverse than four species where one dominates. (Biodiversity and Human Impact)
Thinking an invasive species is any species that is not native. A non-native species is invasive only when it spreads and harms native species, ecosystems or the economy. (Biodiversity and Human Impact)
Believing that a planted forest or large green crop field has the same biodiversity as a natural ecosystem. A monoculture offers one food source and little structural variety. (Biodiversity and Human Impact)
Assuming that every species will be harmed equally by climate change. Some species expand their ranges, but the rapid pace of change leaves many unable to adapt or relocate. (Biodiversity and Human Impact)
Forgetting genetic diversity when discussing conservation. A small population can survive for a while yet still be at risk because it has too little genetic variation to adapt. (Biodiversity and Human Impact)

Practice test

21 questions from across the unit. Each one shows the lesson it comes from.

Classification and Taxonomy
1
Which scientific name is written correctly?
Classification and Taxonomy
2
What term describes the evolutionary history and relationships of a group of organisms?
Classification and Taxonomy
3
Which kingdom contains eukaryotes that are not fungi, plants or animals, such as amoebas and kelp?
Dichotomous Keys and Field Sampling
4
Which couplet is best for a dichotomous key?
Dichotomous Keys and Field Sampling
5
Researchers catch and mark 40 frogs at a pond. A week later they catch 50 frogs, and 10 of them are marked. Estimate the frog population.
frogs
Dichotomous Keys and Field Sampling
6
Why should quadrats be placed at random locations?
Prokaryotes, Eukaryotes and Viruses
7
Which structure is found in both prokaryotic and eukaryotic cells?
Prokaryotes, Eukaryotes and Viruses
8
Which observation most strongly supports the idea that chloroplasts were once free-living bacteria?
Prokaryotes, Eukaryotes and Viruses
9
Name the asexual process by which a bacterium divides into two identical cells.
Protists and Fungi
10
Which structure does a Paramecium use to move?
Protists and Fungi
11
Put the steps of fungal feeding in order.
1. 1Absorbed nutrients fuel growth of more hyphae
2. 2Small molecules are absorbed through the hyphal walls
3. 3Large molecules are broken down outside the hyphae
4. 4Hyphae grow into the food source
5. 5Hyphae release digestive enzymes
Protists and Fungi
12
One Amoeba divides by binary fission every 12 hours. How many divisions occur in 3 days, assuming conditions stay ideal? Give a whole number.
From Algae to Flowers: Plant Diversity and Evolution
13
Arrange these plant groups in the order they first appeared in the fossil record, earliest first.
1. 1Seedless vascular plants (ferns)
2. 2Angiosperms
3. 3Gymnosperms
4. 4Bryophytes
From Algae to Flowers: Plant Diversity and Evolution
14
Why could seed plants spread into dry habitats where ferns struggle?
From Algae to Flowers: Plant Diversity and Evolution
15
Flowering plants first appear in the fossil record about 130 million years ago, and the first land plants about 470 million years ago. Roughly how many million years passed between them? Give a whole number.
The Animal Kingdom: Invertebrates to Vertebrates
16
Which phylum has no true tissues and is asymmetrical?
The Animal Kingdom: Invertebrates to Vertebrates
17
Of the nine phyla in this lesson (Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata, Chordata), how many have three tissue layers? Give a whole number.
The Animal Kingdom: Invertebrates to Vertebrates
18
Match each body-cavity type to an example phylum.
Acoelomate
Pseudocoelomate
Coelomate
Biodiversity and Human Impact
19
Order the levels of biodiversity from the smallest scale to the largest.
1. 1Species diversity
2. 2Genetic diversity
3. 3Ecosystem diversity
Biodiversity and Human Impact
20
Match each human activity to an example.
Invasive species
Overharvesting
Pesticide pollution
Habitat loss
Climate change
Biodiversity and Human Impact
21
Which conservation strategy protects all three levels of biodiversity at once?

Endless drill

Fresh numbers every time, for the calculation questions in this unit.

Endless drillnew numbers every time

Generating a problem…