Cambridge igcse biology ( 2016 2018) classification of living organisms

Cambridge IGCSE Biology

1- Characteristics and classification of living organisms

BiologyCambridge IGCSE Biology

1.1 characteristics of living organisms

Movement : an action by an organism or part of an organism causing change of position


Respiration : the chemical reaction in cells that break down nutrients molecules to

release energy for metabolism


Sensitivity : the ability to detect and respond to change in the environment Extended the ability to detect or sense stimuli in internal or external environment and make appropriate responses


Growth : a permanent increase in Size Extended: a permanent increase in Size and dry mass by an increase in cell number or cell size or both


Reproduction : the process that make more of the same kind of organism


Execration : removal from organisms of toxic material or substances in excessive of requirements Extended: removal from organisms the waste products of Metabolism which is toxic material and substances in excessive of requirements

Nutrition : taking in of material for energy , growth and development Extended: taking in of material for energy , growth and development ; plants need ( light – water – CO2 – ions )Animal need ( organic compounds – ions – water)


1.2 concept and use of Classification classification : putting living organisms in groups referring to common similarities e.g: mammals have hair / breasts to feed babies so Human , horses , dogs belong to one group

All of them are descended from the same ancestor

Distant ancestor

species as a group of organisms that can reproduce to produce fertile offspring

binomial system of naming species as an internationally agreedsystem in which the scientific name of an organism is made up of two parts showing genus and species

1.2 Classification classification : putting living organisms in groups Extended: 1- depending on morphology 2- depending on anatomy

classification : putting living organisms in groups Extended: 3- DNA ( genetic material ) Animal with more similar base of DNA they are more

close and that means they have

recent ancestor

DNA and base pairsBase pairs hold the two strands of the DNA helix together.The rules for base pairing are…

There are millions of base pairs in a DNA molecule that always follow these rules.

A always pairs with T

C always pairs with G

Amazingly, it is the sequence of bases along a DNA molecule that forms the genetic code – it’s that simple!

classification : putting living organisms in groups Extended: 3- DNA ( genetic material ) Animal with more similar base of DNA they are more

close and that means they have

recent ancestor

1.3 features of living organisms

Plant features Animal features

Movement Fixed , stay in one place

Move actively

Nutrition photosynthesis ( autotrophic )

Hunting for food ( heterotrophic )

Cell structure (Cell wall – cell membrane – cytoplasm – nucleus - chloroplast )

(cell membrane – cytoplasm – nucleus)

All living organisms body made of cells contain( cell membrane – cytoplasm – DNA genetic material )

Extended: all living organisms cells contain ribosome for making protein and enzymes for respiration

Animals features 1- Multicellular 2- cells have no cell wall and chloroplasts3- feed on organic substance made by other living organisms Plant features 1- Multicellular 2- cells have cell wall (made of cellulose) and chloroplasts3- feed by photosynthesis4- may have roots , stems and leaves


Extended: Fungi Kingdom 1- usually multicellular 2- have nuclei ( singular : nucleus ) 3- have cell wall made of chitin ( not cellulose ) 4- have no chloroplasts 5- feed by saprophytic or parasitic nutrition


Extended: protoctista Kingdom 1- multicellular – unicellular 2- have nuclei ( singular : nucleus ) 3- may have cell wall and chloroplast 4- some feed by photosynthesis ( Autotrophic) some feed on organic substance made by other organisms ( heterotrophic )


Extended: prokaryotic Kingdom 1- unicellular 2- have no nuclei ( singular : nucleus ) 3- may have cell wall made of cellulose 4- have no mitochondria


Animal kingdom Phylum vertebrate : all animals have backbone called vertebratesclass fish : all live in water - scaly skin – have gills – have fins cold blooded

class amphibians : moist scale less skin – cold blooded tadpoles have gills – adults have lungs

class reptiles : dry scaly skin – lay eggs with water proof shells cold blooded class birds : covered with feathers – lay eggs with water proof shells – have beak have wings - warm blooded


class mammals : body covered with hair – have placenta – young feed on milk from breast warm blooded – have diaphragm have different types of teeth


animal KingdomPhylum : arthropods 1- several pairs of jointed legs 2- exoskeleton 3- segmented body


animal KingdomPhylum : arthropodsinsects 1- 3 pairs of jointed legs 2- breath through trachea 3- body divided into 3 parts ( head - thorax - abdomen )


animal KingdomPhylum : arthropodsCrustaceans 1- more than 4 pairs of jointed legs 2- breath through gills 3- segmented body


animal KingdomPhylum : arthropodsArchnids 1- 4 pairs of jointed legs 2- breath through book lungs 3- segmented body


animal KingdomPhylum : arthropodsMyriapods 1- each segment has pairs of jointed legs 2- exoskeleton 3- many segments in body


Extended: plant kingdomFerns1- plants with roots ,stems and leaves 2- have leaves called fronds 3- do not produce flowers 4- reproduce by spores


Extended: plant kingdomFlowering plants 1- plants with roots ,stems and leaves 2- reproduce sexually by flower and seeds 3- seeds produced inside the ovary


Extended: viruses features 1- all of them pathogen ( cause diseases ) Common cold / influenza / AIDS 2- the can not conceder as living organism – outside cells found as crystals 3- they are not cells and have protein coat 4- genetic material may be DNA or RNA 5- they are smaller than Bacteria


1.4 Dichotomous keys

Education

Cambridge igcse biology ( 2016 2018) classification of living organisms