Features of organisms — Cambridge IGCSE Biology
The features used to place organisms in the animal and plant kingdoms, the vertebrate and arthropod groups, the five kingdoms and viruses.
Revision notes
5 short notes, in the order of the specification. Each one in short:
Animals are multicellular organisms with no cell walls or chloroplasts that feed on other organisms. Plants are multicellular organisms with cellulose cell walls and chloroplasts that make their own food by photosynthesis. Animals store carbohydrate as glycogen and plants store it as starch. To place an organism in a kingdom, compare the same feature in both.
Vertebrates are animals with a backbone, split into five groups: mammals, birds, reptiles, amphibians and fish. Arthropods have a hard exoskeleton, a segmented body and jointed legs, and are split into myriapods, insects, arachnids and crustaceans. Insects have three body parts and three pairs of legs; arachnids have two body parts and four pairs of legs.
The five kingdoms
SupplementThe five kingdoms are animal, plant, fungus, prokaryote and protoctist. Fungi have cell walls made of chitin, have no chloroplasts and feed by absorbing nutrients. Prokaryotes, such as bacteria, are single-celled with no nucleus. Protoctists are mostly single-celled organisms with a nucleus; some have chloroplasts like plants, and others feed like animals.
Ferns, monocots and dicots
SupplementFerns are plants with leaves called fronds that have no flowers and reproduce using spores, while flowering plants reproduce using seeds formed inside the ovary. Flowering plants divide into monocotyledons, with one cotyledon, parallel leaf veins and flower parts in threes, and dicotyledons, with two cotyledons, branching veins and flower parts in fours or fives.
Viruses
SupplementA virus is a particle much smaller than a bacterium that is not made of cells, so it does not fit into the five kingdoms. Its features are limited to two: a protein coat, which surrounds and protects the genetic material, and the genetic material inside it, which carries the instructions for making new viruses.
Exam questions
7 exam-style questions (17 marks), each with its mark scheme.
Answer the questionsFlashcards
15 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of characteristics and classification of living organisms on one page, so you can see where this subtopic fits.
Open the mind mapPrint it
Free PDFs to print or save.
Quick check questions
State two features of plants that animals do not have.
Show answer
Cell walls made of cellulose; chloroplasts (so they photosynthesise).
Name the four groups of arthropods.
Show answer
Myriapods, insects, arachnids and crustaceans.
Name the five groups of vertebrates.
Show answer
Mammals, birds, reptiles, amphibians and fish.
Supplement Name the five kingdoms.
Show answer
Animal, plant, fungus, prokaryote and protoctist.
Supplement State the two features of a virus.
Show answer
A protein coat and genetic material.
Frequently asked questions
How do you tell a plant from an animal in classification?
Plants have cellulose cell walls and chloroplasts and make their own food by photosynthesis; animals have no cell walls or chloroplasts and feed on other organisms. Both are multicellular. Plants store carbohydrate as starch and animals store glycogen, and animals usually have a nervous system while plants do not.
What is the difference between insects and arachnids?
Insects have a body in three parts (head, thorax and abdomen), three pairs of legs, one pair of antennae and usually two pairs of wings. Arachnids, such as spiders, have a body in two parts (cephalothorax and abdomen), four pairs of legs and no antennae or wings. Both are arthropods with jointed legs.
How do you tell reptiles and amphibians apart?
Reptiles have dry skin covered with scales and lay eggs with soft, leathery shells, and most live on land. Amphibians have moist, smooth skin without scales and lay jelly-covered eggs in water. Amphibian larvae, called tadpoles, live in water, while the adults often live on land.
Why are fungi not plants?
Supplement Fungi are not plants because they have cell walls made of chitin, not cellulose, and no chloroplasts, so they cannot photosynthesise. Instead they feed by absorbing nutrients from dead or living organisms. They also store glycogen rather than starch and reproduce with spores, so they form a kingdom of their own.
Why are viruses not in any of the five kingdoms?
Supplement Viruses are not in any of the five kingdoms because they are not made of cells. A virus is much smaller than a bacterium and has only two features: a protein coat and the genetic material inside it. It has no nucleus, cytoplasm or cell membrane, so it cannot be classified like a cellular organism.
Written and checked against the Cambridge IGCSE Biology (0610) specification · Updated October 2026