classification

Question 1

why do scientists classify

Answer 1

organisation: information can easily be accessed and interpreted
communication: a global system that allows scientists to share ideas despite language barriers
further study: patterns and trends are easier to recognise when organisms are grouped together

Question 2

what are the 8 taxonomic levels?

Answer 2

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 3

what are the 3 domains?

Answer 3

Eukarya: all contain nucleus and organelles
Bacteria: simple single celled organisms
Archaea: single celled organelles that live in extreme conditions

Question 4

what are the 6 kingdoms?

Answer 4

Animalia
Plantae
Fungi
Protista
Bacteria
Archaea

Question 5

what are the main categories of characteristics that scientists use to classify organisms

Answer 5

physical
reproductive
genetic

Question 6

explain classifying organisms based on physical characteristics

Answer 6

physical classification can occur at the macro and cellular level.

Question 7

explain how skeletal structure can be used to classify organisms

Answer 7

skeletal structure is a common characteristic with an exoskeleton, endoskeleton, and hydrostatic skeleton
another is asymmetry with bilateral (division of two equal sides) and radial (any number of divisions cut through a central axis)

Question 8

explain segmentation in terms of classifying organisms

Answer 8

segmentation is the division into repeating sections

Question 9

explain classifying organisms based on physical characteristics

Answer 9

the largest difference is reproduction in organisms is sexual (gametes from two individuals) and asexual (single organism reproduction)

Question 10

explain sexual reproduction

Answer 10

in sexual reproduction, many organisms lay eggs whilst others have live young.
some organisms have very long gestational periods while others are very brief

Question 11

what are the types of asexual reproduction?

Answer 11

there are 4 main types of asexual reproduction: fragmentation, binary fission, spores and parthenogenesis

Question 12

how does dna and rna differ?

Answer 12

dna has 4 bases - adenine, cytosine, guanine and thymine

rna also has 4 bases - adenine, cytosine, guanine and uracil

Question 13

what are the two key concepts that the theory of evolution was founded on?

Answer 13

all life forms share a common ancestor and populations change over time due to selective pressures

Question 14

what is a species?

Answer 14

a species is a collection of similar organisms that have the ability to reproduce fertile offspring

Question 15

what is speciation?

Answer 15

speciation refers to the formation of new and distinct species as a result of evolution

Question 16

how does speciation occur?

Answer 16

speciation generally occurs due to isolation. when a population separates, genetic differences due to selective pressures can increase to the point where the two populations can no longer reproduce.

Question 17

what is a clade?

Answer 17

a clade is all the descendants of one ancestor

Question 18

define monophyletic

Answer 18

a group (clade) that contains all of the descendants of the oldest ancestor

Question 19

define paraphyletic

Answer 19

a group that does not contain all the descendants of the oldest ancestor

Question 20

define polyphyletic

Answer 20

a group of organisms from different branches

Question 21

what is dna hybridisation?

Answer 21

dna is double stranded and when it’s heated up it splits (denatures) into two strands, which can join back together when it cools. in hybridisation, a strand of dna is linked to a strand from a different organism. the more similar the organisms, the more they will match up

Question 22

what requirements must something meet in order to be classified as living?

Answer 22

growth and development, use energy, reproduction, be made of cells, response to the environment and adaptation