CDS Biology · Free notes
Biodiversity and Classification: CDS Biology
Biodiversity and Classification has 21 past-year questions in CDS General Knowledge, from 2018 (I) to 2026 (II): 10 EASY and 11 MODERATE. Most of them name an organism and ask where it belongs, so the marks go to students who know a few examples for each group. Fungi are asked often: yeast is a single-celled fungus, and mushrooms and bread mould feed on dead matter. In the animal kingdom, learn the heart chambers of each vertebrate class and the one sign that marks each phylum, such as jointed legs for the arthropods.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
Classification, Plants and Fungi
10 PYQsThe ranks from kingdom down to species, the five kingdoms of living things, the main groups of plants from algae to flowering plants, and how fungi grow and feed.
Animal Phyla and Classes
11 PYQsThe animal phyla from sponges to echinoderms, the organs animals and protists move with, and the chordate classes with their hearts and body temperature.
Formula & revision sheet
0 formulas · 8 reference tables · 16 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 8 reference tables · 16 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (4)
The ranks of classification7 rows
| Rank | Human being | Mango |
|---|---|---|
| Kingdom | Animalia | Plantae |
| Phylum or Division | Chordata | Angiospermae |
| Class | Mammalia | Dicotyledonae |
| Order | Primata | Sapindales |
| Family | Hominidae | Anacardiaceae |
| Genus | Homo | Mangifera |
| Species | sapiens | indicaQ CDS 2020 (II): all the individuals of one kind, such as rose plants, form a species. |
The five kingdoms5 rows
| Kingdom | Cell and body | Nutrition | Examples |
|---|---|---|---|
| Monera | Prokaryotic, single-celled | Varied | Bacteria, blue-green algae |
| Protista | Eukaryotic, single-celled | Varied | Amoeba, Paramecium, Euglena |
| Fungi | Eukaryotic, mostly threads of hyphae; yeast is single-celled | Heterotrophic, mostly saprophytic | Yeast, mushroom, bread mouldQ CDS 2022 (I): the yeast used to make bread is a fungus, not a protist or a moneran. |
| Plantae | Eukaryotic, many-celled, cellulose wall | Autotrophic | Mosses, ferns, flowering plants |
| Animalia | Eukaryotic, many-celled, no cell wall | Heterotrophic | Sponges, insects, human beings |
The plant groups5 rows
| Group | Key feature | Examples |
|---|---|---|
| Algae (Thallophyta) | No root, stem or leaf; mostly in water | Spirogyra, Ulothrix, CharaQ CDS 2020 (II): in Kingdom Plantae, the predominantly aquatic group is the algae. |
| Bryophyta | No vascular tissue; need water to reproduce | Riccia, Marchantia, Funaria |
| Pteridophyta | Vascular tissue but no seeds | Marsilea, ferns, horse-tailsQ CDS 2019 (II): Marsilea, fern and horse-tail are pteridophytes. |
| Gymnosperms | Naked seeds | Pinus, Cycas |
| Angiosperms | Seeds enclosed in a fruit; flowers | Mango, wheat, rose |
How fungi grow and feed6 rows
| Organism | Group | Mode of nutrition |
|---|---|---|
| Agaricus (mushroom) | Fungus | SaprophyticQ CDS 2019 (I): Agaricus is the saprophyte; Ulothrix, Riccia and Cladophora make their own food. |
| Rhizopus (bread mould) | Fungus | SaprophyticQ CDS 2023 (II): the saprophyte among Cuscuta, Rhizopus, Spirogyra and grass is Rhizopus. |
| Yeast | Fungus | SaprophyticQ CDS 2021 (II): yeast, mushroom and bread mould break food down outside the body and absorb it. |
| Cuscuta | Flowering plant | Parasitic |
| Spirogyra | Alga | Autotrophic |
| Amoeba | Protist | Holozoic (takes food in) |
Watch out for (8)
- Order comes before Family→ The ranks of classification
- Species is the basic unit, not genus→ The ranks of classification
- Yeast is a single-celled fungus→ The five kingdoms
- Protozoa is not one of the five kingdoms→ The five kingdoms
- Vascular tissue does not mean seeds→ The plant groups
- Bryophytes live on land, algae in water→ The plant groups
- A plant without chlorophyll is not a saprophyte by default→ How fungi grow and feed
- Hyphae are threads, not spores→ How fungi grow and feed
Reference tables (4)
Sponges, cnidarians and worms5 rows
| Phylum | Body plan | Examples |
|---|---|---|
| Porifera | Pores, no true tissues | Sycon, Spongilla |
| Cnidaria | Radial symmetry, stinging cells | Hydra, jellyfish, sea anemone |
| Platyhelminthes | Flat, bilateral symmetry | Planaria (free-living), liver fluke, tapewormQ CDS 2021 (I): Planaria is the free-living animal; liver fluke, Wuchereria and Plasmodium are parasites. |
| Aschelminthes | Round, unsegmented | Ascaris, Wuchereria |
| Annelida | Segmented, bilateral symmetry | Earthworm, leech, NereisQ CDS 2019 (I): Nereis is the bilaterally symmetrical one; sea anemone, starfish and sea urchin are not. |
Organs of locomotion7 rows
| Organism | Organ of locomotion |
|---|---|
| Amoeba | Pseudopodia |
| Euglena | Flagellum |
| Paramecium | Cilia |
| Nereis | ParapodiaQ CDS 2018 (I): Nereis with pseudopodia is the wrongly matched pair. |
| Earthworm | Body-wall muscles and setae |
| Starfish | Tube feet |
| Snail | Muscular foot |
Arthropods, molluscs and echinoderms3 rows
| Phylum | Sure sign | Examples |
|---|---|---|
| Arthropoda | Jointed legs, exoskeleton | Insects, spiders, prawn, silverfishQ CDS 2021 (II): jointed legs confirm that an animal is an insect and not an earthworm. |
| Mollusca | Soft body, shell, muscular foot | Oyster, Pila, octopus, cuttlefishQ CDS 2020 (II): pearls are harvested from oysters. |
| Echinodermata | Spiny skin, tube feet | Starfish, sea urchin |
Chordates and their hearts6 rows
| Group | Heart and body temperature | Examples |
|---|---|---|
| Protochordata | Notochord, but never a backbone; cold-blooded | Balanoglossus, Herdmania, AmphioxusQ CDS 2021 (II): marine, with a notochord, but never a vertebral column: Protochordata. |
| Pisces | Two chambers; cold-blooded | Rohu, shark (Scoliodon), flying fishQ CDS 2018 (I): of silverfish, jellyfish, cuttlefish and flying fish, only the flying fish is a true fish. |
| Amphibia | Three chambers; cold-blooded | Frog, toad, salamanderQ CDS 2018 (I): the classes with a three-chambered heart are Amphibia and Reptilia. |
| Reptilia | Three chambers (four in crocodiles); cold-blooded | Lizard, snake, tortoise, crocodile |
| Aves | Four chambers; warm-blooded | Pigeon, peacock, ostrichQ CDS 2019 (I): the warm-blooded pair is peacock and camel. |
| Mammalia | Four chambers; warm-blooded | Camel, bat, whale, human being |
Watch out for (8)
- Not every flatworm is a parasite→ Sponges, cnidarians and worms
- Starfish are radial as adults→ Sponges, cnidarians and worms
- Pseudopodia belong to Amoeba→ Organs of locomotion
- Segments do not make an insect→ Arthropods, molluscs and echinoderms
- Pearls come from oysters, not snails→ Arthropods, molluscs and echinoderms
- Only birds and mammals are warm-blooded→ Chordates and their hearts
- Most fish names are not fish→ Chordates and their hearts
- Reptiles are three, except the crocodile→ Chordates and their hearts
PYQ weightage by concept
8 concepts · 21 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
8 concepts · 21 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| How fungi grow and feed | 4 | 19% |
| The ranks of classification | 2 | 10% |
| The five kingdoms | 2 | 10% |
| The plant groups | 2 | 10% |
| Concept | PYQs | Share |
|---|---|---|
| Chordates and their hearts | 5 | 24% |
| Sponges, cnidarians and worms | 3 | 14% |
| Arthropods, molluscs and echinoderms | 2 | 10% |
| Organs of locomotion | 1 | 5% |
Test yourself on Biodiversity and Classification
10 past CDS questions from this chapter, timed at 10 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.