Classification
Why we classify organisms, the levels from kingdom to species, the definition of a species and the binomial name, the five kingdoms, vertebrate and arthropod groups, and how to use a dichotomous key. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
Practice
- Check yourself: Classification – Type the missing words, put the steps in order and write a short answer. No multiple choice: you have to remember it.
Transcript
Classification means sorting living things into groups. We use the features that they share.
There are millions of different organisms. Groups make them easier to study and to name.
The groups get smaller and smaller. The levels are kingdom, phylum, class, order, family, genus and species. Humans are in the animal kingdom, then the phylum Chordata, the class Mammalia, the order Primates, the family Hominidae, the genus Homo, and the species sapiens.
A species is a group of organisms that can reproduce to make fertile offspring. Lions and tigers are different species.
Every species has a two-part Latin name. This is the binomial system. The first part is the genus, with a capital letter. The second part is the species, with a small letter. For humans it is Homo sapiens.
There are five kingdoms. Animals are many-celled organisms. They feed on other organisms. Plants are many-celled organisms with chloroplasts, so they make their own food.
Fungi have cell walls, and feed on dead material. Protoctists are mostly single cells with a nucleus. Prokaryotes, such as bacteria, are single cells with no nucleus.
Animals are divided into groups. Vertebrates have a backbone. The five groups of vertebrates are mammals, birds, reptiles, amphibians and fish.
Invertebrates have no backbone. Arthropods are invertebrates with jointed legs and a hard outer skeleton. The four groups are insects, arachnids, crustaceans and myriapods.
A dichotomous key helps us to name an organism. It is a set of questions, and each question has two answers: yes or no.
We start at the top and follow the answers. Each answer leads to another question, or to the name of the organism.
Remember. Classification sorts organisms into groups. The levels go from kingdom down to species. A species can reproduce to make fertile offspring. The binomial name has a genus and a species. And a dichotomous key uses yes or no questions to name an organism.
More in this series
8:08B1 Characteristics and classification: key vocabulary
Sixteen key words for IGCSE Co-ordinated Sciences topic B1 (characteristics and classification of living organisms), with the Vietnamese meaning, how to say each word, a picture and an example. Ends with a test section, and a typing trainer on the site that also practises twelve general science words.
2:44Characteristics of living things
The seven characteristics of all living organisms (movement, respiration, sensitivity, growth, reproduction, excretion, nutrition), each with a picture, and the word MRS GREN to remember them. With Vietnamese subtitles. A “Check yourself” section with typed questions is below the video on the site.
5:29B1 quiz: characteristics and classification
Ten think-time questions on the seven characteristics of living things, species, the binomial name, kingdoms, vertebrates and arthropods, and dichotomous keys.