Igcse bio: Classification

Taxonomy

placing living organisms into categories on the basis of morphology and anatomy, to make it easier for scientists

Morphology

overall form and body shape of living organisms

anatomy

internal body structure by dissection

Recently they use DNA analysis

-organisms which are closely related have similar base sequence in DNA

Advantages of using DNA:

accurate, faster, cheaper and allow larger scale identification and only trace sample used

King Phillip came over for grandma’s spaghetti

Kingdom Phylum Class Order Family Genus Species

Genus

group of organisms similar to each other but if breed they breed they wil produce infertile offsprings

species

group of living organisms share the same characteristics and if they breed together they will produce fertile offspring

Binomial naming system

First is the genus name: starts with capital letter

Second if the species name: starts with small letter

eukaryotes

all have their DNA enclosed in a nucleus they are classified into 4 kingdorm

-Animals

-Plants

-Fungi

-Protocitist

animals

multicellular, no cell wall, heterotrophs (feed on other organisms)

Plants

Multicellular, Have cell wall, Made from cellulose, autotrophs

Fungi

Cell wall (+large vacuole), made from chitin not cellulose, usually multicellular, saprophytic (decomposers) or parasitic (cause disease)

protocitist

-may have cell wall made of cellulose (have chloroplast so autotrophs)

-while some may have no cell wall (no chloroplast so feed as heterotrophs)

viruses

viruses couldn't be added to one of the five kingdoms, as they don't show the typical features of living organisms, in other words they are parasites that feed and reproduce on the host cell causing harm to their host.

Animals (vertebrates)

vertebrates (have back bone) and invertebrates (no backbone)

mammals (vertebrates)

Body covered with hair/ fur

Give birth Feed / suckle their babies with milk

Have mammary glands Whiskers

Have external ear/pinna Different types of teeth Heart with 4 chambers

reptile (vertebrates)

Body covered with a dry scaly skin

Lay rubbery / leathery shelled eggs

amphibians (vertebrates)

Have moist skin Lay jelly coated eggs in water

Young breath through gills

Adult breath through lungs

Birds (vertebrates)

Have wings Beak

Feathers Lay hard shelled eggs

Legs covered with scales

fish (vertebrates)

Scales Gills Fins and tail Lay jelly coated eggs

Arthropods (invertebrates)

All arthropod

1. Segmented body

2. Jointed legs

3. Exoskeleton

Myriapods

many pairs of jointed legs and body parts

Crustaceans

number of pairs of jointed legs: 5

Number of body parts: 2

other key features: chalky exoskeleton, 2 pairs of antenna

archnids

number of pairs of jointed legs: 4

Number of body parts: 2 (cephalothorax, abdomen)

other key features: no antenna

Insects

number of pairs of jointed legs: 3

Number of body parts: 3 (head, thorax, abdomen)

other key features: 1 pair of antenna, 1 or 2 pairs of wings, compound eyes

Flowering plants

They have roots, stem , leaves

They have xylem and phloem

Reproduce sexually by producing seeds

Seeds are produced in ovary of flower

Non flowering plants

1. They have root , leaves and stem

2. Have xylem and phloem in stem ( they are short tubes with no open ends )

3. Leaves are called fronds

4. They reproduce by producing spore ( asexual) 5. They don’t have thick cuticle , can only survive in shady , humid areas .

Monocotyledon

Seed: one cotyledon

Leaves: no leaf petiole (no stalk) narrow elongated leaves parallel veins

Petal: multiplies of 3

Root: fibrous root

Dicotyledon

Seed: 2 cotyledon

Leaves: leaf petiole, broad oval leaves, network vein

Petal: 4 or 5 petals

Root: Tab root

non- flowering plants

1. They have root , leaves and stem

2. Have xylem and phloem in stem ( they are short tubes with no open ends ) 3. Leaves are called fronds

4. They reproduce by producing spore ( asexual)

5. They don’t have thick cuticle , can only survive in shady , humid areas .

Non-flowering plants

1. Frond complex leaves with short conducting tubes ( xylem and phloem ) Stem has phloem and xylem

2. Rhizome ( underground stem ) for storage .