I/GCSE Biology - Human Biology

I/GCSE Biology - Human Biology

Human Biology - Classification

July 11, 2021

How to classify organism?

There are millions of different plants and animals in the world. To make it easier to identify them, we place them into different groups. These groups contain organisms whose characteristics are similar. The process of classifying organism is called taxonomy. Classification itself means identifying and grouping organisms.

Living organisms are placed into groups, called kingdoms.

In I/GCSE Biology, there are five kingdoms:

1.Plants	Multicellular (Their bodies are made up of many cells) Cells contain chloroplasts which carry out photosynthesis (carbon dioxide + water -> glucose + oxygen) Contains a stem, roots, leaves and the flower Cells contain (in addition to nucleus, cell membrane and cytoplasm) cell wall, vacuole and chloroplasts
2.Animals	Movement involves coordination by the nervous system Gains energy by feeding on other animals/plants Cells lack cell walls so they can change shape
3.Fungi	Some such as mushrooms and Mucor are Multicellular. Others such as yeasts are unicellular (made of single cells). Cannot carry out photosynthesis Body is usually organized into a mycelium made from thread-like structures called hyphae. They have cell walls made of chitin Feed on nutrients from the dead – or they decompose by producing extracellular enzymes that digest the dead material outside of the organsim Produces spores for reproduction
4.Protoctists	Examples include amoeba, chlorella and plasmodium (which is responsible for malaria)
5.Prokaryotes	Examples include bacteria

Bacteria 🦠

Unicellular – have a cell wall, cell membrane, cytoplasm and plasmids
Lacks nucleus but contains DNA
Some can photosynthesis but most feed off other living or dead organisms
Examples include Lactobacillus bulgaricus

Viruses are parasitic, smaller than bacteria, have no cellular structure but have a protein coat and one type of nucleic acid, either DNA or RNA. They can only reproduce inside living cells and infect every type of living organism. Examples include the influenza virus, and HIV. Fungi, bacteria, protoctists or viruses can be pathogens – agents that cause disease.

*Note: Viruses are NOT living things. They do not feed, respire, excrete, move, grow or respond to their surroundings. They only reproduce – but they do it parasitically by entering a host cell and taking over the host’s genetic machinery to make more virus cells.

How to define ‘Living’ ?

In I/GCSE Biology, 'living' means they all have things as below: 👇👇

Movement

Respiration

Senses

Growth

Reproduction

Excretion

Nutrition

Genus V.S. Species

A genus is the second last classification group. Kingdoms such as animals are divided into smaller groups such as mammals. That can then be divided into even smaller groups such as… dolphins! And then even smaller, such as pink-nose dolphin! Get the idea? Unfortunately we’re talking about Latin names here.

Key point here: No different species can reproduce with each other.

An example would be Homosapien. ‘Homo’ is the genus, because there are lots of other ‘Homos’ out there such as Homo neanderthelansis. ‘Sapien’ is the species name.

Other Groups Lower Down Kingdoms 👇👇

Kingdom
Phylum
Class
Order
Family
Genius
Species

Kate Perry Cooks Only For Good Singers

Anyways these are the groups from the biggest down to the smallest – or from the very first level of classification down to the last.😁😁😁

That's the end of the topic!

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Drafted by Joey (Biology)