Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Classification & biodiversity

Topic 5
...
5 million named and described species on Earth
○

Probably 10-100 million species not named nor described

➢ The first name in the binomial nomenclature system is always capitalized and it
refers to the genus
➢ The second name always begins with a small letter and refers to the species
○

Both are written in italics when typed or underlined when written by hand

➢ This system has been internationally agreed upon and is constantly being revised
during several congresses
➢ The binomial nomenclature was founded by Carolus Linnaeus (Carl von Linné) in
1735
➢ Species were put into genera only by appearance
○

With modern DNA technology more accurate methods can be used

○

The appearance of an organism is still the main method to determine a
species taxonomy

○

Since the start many species have been reclassified

➢ Examples:
○
○
○
○
○
○

Amoeba amazonas
Equus zebra
Gekko gecko
Loxodonta cyclotis
Gorilla gorilla
Paramecium caudatum

Taxa
➢ The term taxa (sin
...
3

Biology SL

The domain in which we find the bacteria

Eukaryote domain
■

The domain in which we find all other life

■

They have membrane-bound nucleus and organelles

➢ Each of the 3 domains is subdivided into these 7 taxa
○

Kingdom

○

Family

○

Phylum

○

Genus

○

Class

○

Species

○

Order

➢ The higher taxa have very general characteristics
encompassing many types of organisms and the lower taxa have increasingly
specific characteristics

Taxa

Human

Garden peas

Kingdom

Animalia

Plantae

Phylum

Chordata

Angiospermophyta

Class

Mammalia

Dicotyledoneae

Order

Primate

Rosales

Family

Hominidae

Papilionaceae

Genus

Homo

Pisum

Species

sapiens

sativum

➢ There are countless other ways to classify organisms
○

Feeding habits

○

Habitat

○

Daily activity

○

Risk

○

Anatomy

➢ No single classification system is the “right” way
...
3

Biology SL

Common ancestral species
➢ The scientific name of a species is based on common ancestral species
○

The species within the same genus share many characteristics

○

The members of this genus will have all evolved from a common ancestor

➢ Natural classification uses ancestry to group organisms together
➢ Artificial classification uses arbitrary characteristics to group organisms
➢ Reasons to categorize living organisms using natural classification
○

Trying to make sense of biosphere

○

Showing evolutionary links

○

Predicting shared characteristics

Examples of plant phyla

➢ Bryophyta
○ Includes plants of very short stature
○

Non-vascular plants

○

They reproduce with spores spread by rain and wind

○

No flowers

➢ Filicinophyta
○ Includes ferns and horsetails among others
○

Vascular plants

○

They reproduce with spores spread by rain and wind

➢ Coniferophyta
○ Includes cedar, juniper, fir and pine trees among others
○

Have needle shaped leaves

○

Have vascular tissues

○

They reproduce with seed formed in cones which are spread by wind

➢ Angiospermophyta
○ Includes all flowering plants
○

If the fruit has any seeds inside, then the plant belongs to this phylum

○

Rely on birds, insects and sometimes mammals to transport their pollen

○

The sexual reproductive organs of angiosperms are their flowers
■

○

The fruits is the enlarged ovary and holds the seeds

Have vascular tissues

Examples of animal phyla
➢ 6 out of 6 categories considered here are invertebrates, which means that they
don’t have any backbone
3

Classification & biodiversity

Topic 5
...
3

Biology SL

The animals of this phylum are called vertebrates
■

Have a bony backbone
●

Some fish have cartilaginous spine

●

There are exceptions (f
...
3

Biology SL

●

Have beaks with no teeth

●

Their heartbeat and breathing rates are relatively fast
because they have a high rate of metabolism

●

Capable of thermoregulation, which means that their blood
warms up their body

■

Mammals
● Includes foxes, hippos, squirrels and camels
●

Have fur

●

The females produce milk in specialized glands to feed their
young

●

Capable of thermoregulation

●

Amniotes

●

Most have limbs adapted for life on land, some are adapted
for life in water and others are adapted to fly

Dichotomous key
➢ A dichotomous key is used when a biologist encounters a new species they don’t
recognise yet
➢ It helps us establish what species it is

6



---