4.2.2 Classification and Evolution Flashcards
1
Q
What is classification?
A
- the act of arranging organisms into groups based on their similarities and differences
- making it easier for scientists to identify and study them
2
Q
What is taxonomy?
A
- the study of classification
3
Q
Describe the taxonomic hierarchy and the eight levels of taxonomic groups
A
- 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
4
Q
What are the five kingdom classification system kingdoms?
A
- prokaryotae
- protoctista
- fungi
- plantae
- animalia
5
Q
Give an example of prokaryotae and explain its features
A
- bacteria
- prokaryotic
- unicellular (single-celled)
- no nucleus
- less than 5 nano meters
6
Q
Give an example of protoctista and explain its features
A
- algae
- Protozoa
- eukaryotic cells
- usually live in water
- single-called or simple multicellular organisms
7
Q
Give an example of fungi and explain its features
A
- mould
- yeasts
- mushroom
- eukaryotic
- chitin cell wall
- saprotrophic (absorb substances from dead or decaying organisms)
- singled-called or multicellular
8
Q
Give an example of plantae and explain its features
A
- mosses
- ferns
- flowering plants
- eukaryotic
- multicellular
- cell walls made of cellulose
- can photosynthesise
- contain chlorophyll
- autotrophic (produce own food)
9
Q
Give an example of animalia and explain its features
A
- molluscs
- insects
- fish
- birds
- mammals
- reptiles
- eukaryotic
- multicellular
- no cells walls
- heterotrophic (consume plants and animals)
10
Q
What is nomenclature?
A
Naming system
11
Q
What is the nomenclature used for classification?
A
- binomial system
- first part of the name is genus
- second part is the species
- helps to avoid confusion of using common names
12
Q
What is phylogeny?
A
- the study of the evolutionary relationship between organisms
- tells us who is related and how closely related they are
13
Q
What can be shown by the phylogenetic tree?
A
- all organisms have evolved from shared common ancestors
14
Q
Why are there problems with early classification systems?
A
- they only use superficial observable features and the way they affect people e.g. artificial classification
15
Q
Give examples of other types of evidence that show how similar organisms are to each other?
A
- 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
16
Q
Describe the comparison between five Kingdoms classification system and newer Three Domains system
A
- 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
17
Q
Why was the Three Domain System proposed?
A
- 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
18
Q
What is variation?
A
- the differences that exists between individuals
- it can occur within species (intraspecific) and between species (interspecific)
19
Q
What is continuous variation and give examples of it
A
- 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
20
Q
What is discontinuous variation and give examples?
A
- 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)
21
Q
What can variation be caused by?
A
- genetic factors
- environmental factors
- combination of both
22
Q
How can variation be caused by genetic factors?
A
- 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
23
Q
How can variation be caused by environmental factors?
A
- 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
24
Q
How can variation be caused by environmental and genetic factors?
A
- 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
25
Q
What are the benefits of adaptation?
A
- an organism can increase its chances of survival and reproduction and also the chances of its offspring reproducing successfully
26
Q
What are the three type of adaptation?
A
- 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
27
Q
What is an ecological niche?
A
- the role of an organism within its habitat: what it eats, when and where it feeds
28
Q
Describe the difference between marsupials and placental mammals
A
- 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
29
Q
What is convergent evolution?
A
- 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.
30
Q
Give an example of convergent evolution
A
- 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
31
Q
What are the four observations Darwin made ?
A
- 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
32
Q
What is Darwin’s theory of evolution by natural selection?
A
- 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
33
Q
What evidence supports evolution?
A
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
34
Q
Describe how the evolution of pesticide resistance is explained by natural selection
A
- 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
35
Q
What are the implication for humans due to the evolution of pesticide resistance
A
- 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
36
Q
How has the evolution of drug resistance affected humans?
A
- 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
