4.2.2 Classification and Evolution

Question 1

What is classification?

Answer 1

• the act of arranging organisms into groups based on their similarities and differences
• making it easier for scientists to identify and study them

Question 2

What is taxonomy?

Answer 2

• the study of classification

Question 3

Describe the taxonomic hierarchy and the eight levels of taxonomic groups

Answer 3

• similar organisms are first sorted into one of three very large groups called domains
• e,g. Plants, Animals and fungi are in eukarya domain
• then since organisms are organised into smaller groups called kingdoms
• e,g. Animal kingdom
• similar organisms from that kingdom are grouped into phylum
• then class
• order
• family
• genus
• species

Question 4

What are the five kingdom classification system kingdoms?

Answer 4

• prokaryotae
• protoctista
• fungi
• plantae
• animalia

Question 5

Give an example of prokaryotae and explain its features

Answer 5

• bacteria
• prokaryotic
• unicellular (single-celled)
• no nucleus
• less than 5 nano meters

Question 6

Give an example of protoctista and explain its features

Answer 6

• algae
• Protozoa
• eukaryotic cells
• usually live in water
• single-called or simple multicellular organisms

Question 7

Give an example of fungi and explain its features

Answer 7

• mould
• yeasts
• mushroom
• eukaryotic
• chitin cell wall
• saprotrophic (absorb substances from dead or decaying organisms)
• singled-called or multicellular

Question 8

Give an example of plantae and explain its features

Answer 8

• mosses
• ferns
• flowering plants
• eukaryotic
• multicellular
• cell walls made of cellulose
• can photosynthesise
• contain chlorophyll
• autotrophic (produce own food)

Question 9

Give an example of animalia and explain its features

Answer 9

• molluscs
• insects
• fish
• birds
• mammals
• reptiles
• eukaryotic
• multicellular
• no cells walls
• heterotrophic (consume plants and animals)

Question 10

What is nomenclature?

Answer 10

Naming system

Question 11

What is the nomenclature used for classification?

Answer 11

• binomial system
• first part of the name is genus
• second part is the species
• helps to avoid confusion of using common names

Question 12

What is phylogeny?

Answer 12

• the study of the evolutionary relationship between organisms
• tells us who is related and how closely related they are

Question 13

What can be shown by the phylogenetic tree?

Answer 13

• all organisms have evolved from shared common ancestors

Question 14

Why are there problems with early classification systems?

Answer 14

• they only use superficial observable features and the way they affect people e.g. artificial classification

Question 15

Give examples of other types of evidence that show how similar organisms are to each other?

Answer 15

• molecular evidence: the similarities in proteins and DNA
  > - more closely related organisms have more similar molecules
  > - you can compare how DNA is stored and the sequence of DNA bases e.g. base sequence of DNA
  > - you can also compare the sequence of amino acids in proteins from different organisms
• embryological evidence: the similarities in the early stages of an organism’s development
• anatomical evidence: the similarities in structure and function of different body parts
• behavioural evidence: the similarities in behaviour and social organisation of organism

Question 16

Describe the comparison between five Kingdoms classification system and newer Three Domains system

Answer 16

• in the older system, the large groups were the five kingdoms, all organisms were placed into one of these groups
• in 1990, the three domain system was proposed
• it has three domains: three super kingdoms that are above the kingdoms in the taxonomic hierarchy
• organisms that were in the kingdom Prokaryotae (contacting unicellular organisms without a nucleus) are separated into two domains - Archaea and Bacteria
• organisms that contain a nucleus are placed in the domain Eukarya (with 4/5 kingdoms)
• the lower hierarchy stays the same

Question 17

Why was the Three Domain System proposed?

Answer 17

• new evidence:
• molecular evidence: the enzyme RNA polymerase (needed to make RNA) is different in Bacteria and Archaea
  > - archaea, have similar histones to Eukarya
• cell membrane evidence: the bonds of the lipids in the cell membranes of Bacteria and Archaea are different.
  > - the development and composition of flagella are also different

Question 18

What is variation?

Answer 18

• the differences that exists between individuals

- it can occur within species (intraspecific) and between species (interspecific)

Question 19

What is continuous variation and give examples of it

Answer 19

• the individuals in a population vary within a range
• there are no distinct categories
• milk yield (animals)
• mass (plants and animals)
• number of leaves (plants)
• width and length of microorganisms

Question 20

What is discontinuous variation and give examples?

Answer 20

• there are two or more distinct categories
• each individual falls into only one of these categories
• there are no intermediates
• blood group (animals)
• colour (plants)
• seed shape (plants)
• antibiotic resistance (microorganisms)
• pigment production (microorganisms)

Question 21

What can variation be caused by?

Answer 21

• genetic factors
• environmental factors
• combination of both

Question 22

How can variation be caused by genetic factors?

Answer 22

• different species have different genes
• individuals of the same species have the same genes but different alleles
• the genes and alleles an organism has makes up its genotype
• the differences in genotype result in variation in phenotype (the characteristics displayed by an organism)
• e.g. variation only caused by genetic factions include blood group and antibiotic resistance
• variation caused by genetic factors is inherited

Question 23

How can variation be caused by environmental factors?

Answer 23

• variations can also be caused by difference in the environment e.g. climate, food, lifestyle
• characteristics controlled by environmental factors can change over an organisms’s life
• e.g. variation caused only by environmental factors include accents or pierces ears

Question 24

How can variation be caused by environmental and genetic factors?

Answer 24

• genetic factors determines the characteristic the organisms are born with, but environmental factors can influence how some of the characteristics develop
• e.g height: genes determine how tall an organism can grow , but diet or nutrient availability affects how tall it can actually grow
• flagellum: some will only grow in certain environments e.g. when metal ions are present

Question 25

What are the benefits of adaptation?

Answer 25

• an organism can increase its chances of survival and reproduction and also the chances of its offspring reproducing successfully

Question 26

What are the three type of adaptation?

Answer 26

• behavioural adaptation: the way an organism acts that increases its chances of survival
  > e.g. bird calls, migration
• physiological adaptation: processes inside an organism’s body that increases its chance of survival
  > e.g. hibernation in brown bears: lowers rate of metabolism over winter, conserving energy
• anatomical adaptation: structural features
  > e.g. thick layer of blubber in whales

Question 27

What is an ecological niche?

Answer 27

• the role of an organism within its habitat: what it eats, when and where it feeds

Question 28

Describe the difference between marsupials and placental mammals

Answer 28

• marsupials are found mainly in Australia and the Americas
• they diverged from placental mammals many millions years ago

marsupial mammals (e.g. kangaroos):

• have a shorter gestation period
• don’t develop a full placenta
• are born early in their development and climb into their mother’s pouch, then becoming attached to a teat and receive milk to develop

placental mammals:

• have a longer gestation period
• develop a placenta during pregnancy, allowing the exchange of nutrients and waste products
• born fully developed

Question 29

What is convergent evolution?

Answer 29

• convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.

Question 30

Give an example of convergent evolution

Answer 30

• marsupial moles and placental moles aren’t closely related, evolved independently in different continents
• share similar anatomical features because they’ve evolved to live in similar environments
• both live in tunnels in the ground
• burrow to reach their food supply
• small, non existent eyes because they don’t need to be able to see underground
• no external ears to keep a streamlined head
• scoop-shaped and power front paws, good for digging
• claws specialised for digging
• tube shaped body and cone shaped head, making it easier to push through sand or soil

Question 31

What are the four observations Darwin made ?

Answer 31

• organisms produce more offspring than survive
• there’s variation in characteristic of members of the same species
• some of these characteristics can be passed on from one generation to the next
• individuals best adapted to their environment are more likely to survive

Question 32

What is Darwin’s theory of evolution by natural selection?

Answer 32

• individuals within a population show variation in their phenotypes (characteristics) because of different alleles due to genetic mutation
• selection pressures (e.g. disease, competition, predation) create a struggle for survival
• individuals with better adaptations are more likely to survive and have reproductive success
• as they reproduce they pass on those adaptations to their offspring
• over time, the proportion of the population possessing the advantageous adaptation increases
• over generations, this leads to evolution

Question 33

What evidence supports evolution?

Answer 33

fossil record evidence:

• fossils are the remains of organism preserved in rocks
• by arranging fossils in chronological order, gradual changes in organisms can be observed that provide evidence for evolution

DNA evidence:

• theory of evolution suggests that all organisms have evolved from shared common ancestors
• closely related species diverged more recently
• evolution is caused by gradual changes in the base sequence of an organisms’ DNA
• organisms diverged away from each other more recently, should have more similar DNA, as less time has passed for changes in the DNA sequence to occur

Molecular evidence:

• similarities in other molecules other than DNA are compared
• e.g. sequence of amino acids in proteins and compare antibodies
• organism that diverged away have more similar molecules

Question 34

Describe how the evolution of pesticide resistance is explained by natural selection

Answer 34

• there is variation in a population of insects
• genetic mutation create alleles that make some insects naturally resistant to a pesticide
• if the population of insects is exposed to that pesticide only the individuals with resistance will survive to reproduce
• the alleles which cause the pesticide resistance will be passed on to the next generation’s so the population will evolve

Question 35

What are the implication for humans due to the evolution of pesticide resistance

Answer 35

• crop infestations with pesticide-resistance insects are harder to control, crops may be destroyed
• they may have to use broader pesticides which could kill beneficial insects
• if disease-carrying insects become pesticide-resistance, the spread of disease could increase
• new pesticides take time and money

Question 36

How has the evolution of drug resistance affected humans?

Answer 36

• pathogens have evolved resistance to specific drugs
• this means infections caused by drug resistance microorganism are harder to treat, which can cause the patient to worsen or even die
• developing new drugs takes time and money