A Level CIE Biology: 18 Classification, Biodiversity & Conservation

species (biological species concept)

a group or organisms with similar morphological and physiological features that able to breed together and produce fertile offspring

biological species concept

reliant on determining whether inbreeding produces fertile offspring - difficult and time consuming to determine in practice. other discriminating factors that scientists can use to group similar orgs together

morphological species concept

• scientists described by physical features and group together orgs that share many physical features that distinguish them from other species.

ecological species concept

• when there’s a population of similar orgs living in same area at the same time, they can be described as an ecological species

taxonomy

practice of biological classification involving placing orgs into series of categories/taxa to make it easier to see evolutionary relationshisp between orgs.

domain

highest rank of hierarchical classification

cell types (major) role in classification of orgs into the 3 domains

• prok cells easily distinguishable in that they lack a nucleus

• euk cells have compartmentalised structures, w at least their genetic material segregated from rest of cell in a nucleus

• prok are divided into 2 separate groups based on molecular analysis of rna genes proving cell type insufficient classification

3 domains:

• archaea (prok)

• bacteria (prok)

• eukarya (euk)

archaea features 9

• single-celled/unicellular orgs

• sometimes extremophile prokaryotes (live in extreme environments but not all)

• no nucleus

• not bacteria bc: 3

  • unique lipids in membranes of cells

  • no peptidoglycan in cell walls

  • ribosomal structure (particularly that of small subunit) more similar to euk ribosome than bac

• similar size range

• dna transcription similar to euk

• e.g. haloboacterium salinarium (dead sea)

bacteria features 5

• single-celled/unicellular

• prok no nucleus

• vary in size over wide range (smallest are bigger than alrgest known viruses and largest smaller than singlecelled euk

• divide by binary fission

• e.g. streptococcus pneumoniae

eukarya features

• orgs w euk cells w nuclei and memb-bound organelles placed in this domain

• vary massively in size from single-celled orgs several micrometres across to large multicellular orgs many metres in size e.g. blue whales

• euk cells diivde by mitosis

• euks can reprod sexually or asexually

• e.g. canis lupus

3 main diffs between archaea and bacteria

• membrane lipids

• ribosomal rna

• cell wall composition

membrane lipid differences 3

• archaras are completely unique, memb lipids consist of brancched hydrocarbon chains bonded to glycerol by ether linkages

• memb lipids of bacteria unbranched hydrocarbon chains bonded to glycerol by ester linkages

• not in bacterial or euk cells

ribosomal rna differences 4

• both archaea and bacteria posses 70s ribosomes

• 70s ribs in archaea possess a smaller subunit similar to subunit in euk rib than sub in bac

  • base sequences of ribosomal rna in archae more similar to rRNA of eukarya

  • prim structure of ribosome proteins in archae more sim to ribosome proteins in eukarya than bacteria

composition of cell walls differences

• bacteria always peptidoglycan

• archaea always cell walls but not peptidoglycan

archaea: cell type, chromosome, cell memb lip, ribosome, cell walls, histones, introns

• prok

• circular

• glycerol - ether lipids

• 70s ribs but small subunit more similar to euk ribs

• always present w/o peptidoglycan

• yes

• sometimes

bacteria: cell type, chromosome, cell memb lip, ribosome, cell walls, histones, introns

• prok

• circ

• glycerol - ester lipids

• 70s ribs

• always present w peptidoglycan

• no

• rarely

euk: cell type, chromosome, cell memb lip, ribosome, cell walls, histones, introns

• euk

• linear chromosomes + circular mtDNA and cpDNA

• glycerol - ester lipids

• large 80s ribosomes in cytosol and 70s ribosomes in mitoch and chloro

• sometimes present w/o peptidoglycan

• yes

• yes

hierarchical classification system of organisms

used to organise and group similar organisms together so that evolutionary relationships between orgs more easily understood

7 taxonomic ranks (domain highest, species lowest)

• similar species grouped in genus

• similar genuses grouped in family

• similar fams grouped in order

• similar orders grouped into class

• similar classes grouped into phylum

• similar phyla can be grouped into kingdom

• similar kingdoms can be grouped into domain

DUMB KINGS PLAY CHESS ON FANCY GOLD SQUARES

wolf and hibiscus down the taxonomic ranks

wolf: eukarya, animalia, chordata, mammalia, carnivora, canidae, canis, lupus

hibiscus: eukarya, plantae, angiospermae, dicotyledonae, malvales, malvaceae, hibiscus, rosa-sinensis

4 kingdoms of eukarya

have distinct char and features

• protoctista (protoctists)

• fungi

• plantae (plants)

• animalia (animals)

2 similarities of all kingdoms of eukarya

• have cells w membrane bound nuclei separating genetic material from cytoplasm

• have compartmentalisation within cells as result of presence of other organelles

kingdom protoctista features 4

• eukaryotic (all euk that don’t belong to other 3)

• show great diversity in all aspects of life (structure, life cycle, feeding, trophic levels, modes of locomotion)

• can be single-celled or group of similar cells

• protozoa has no cell wall like animals but algae have cellulose cell walls and chloroplasts like plants, both protoctists

kingdom fungi 6

• oldest org in world (1500-10,000 yo)

• euk

• cells of fungi have non cellulose cell walls (chitin and glucans) and no cilia

• fungi are heterotrophs

• reproduce using spores that disperse onto ground nearby

• have a simple body form - can be unicellular (yeast - Saccharomyces cerevisiae), can have long threads called hyphae from main fungus (mycelium), or larger fungi posses fruiting bodies that release large no. spores

heterotrophs

use organic compounds made by other organisms as their source of energy and molecules for metabolism. obtain energy and carbon by digesting dead/decaying matter extracelliularly or from being parasites on living orgs.

kingdom plantae features 8

• multicellular euk orgs

• cellulose cell walls

• possess large (usually permanent) vacuoles for structural support

• can differentiate into specialised cells to form tissues and organs

• chloroplasts for photosyn (not all plant cells have)

• can sometimes have flagella

• autotrophs

• complex body forms (branching systems above and below ground)

autotrophs

can synthesise organic compounds and mols for energy use and building biomass from inorganic compounds

kingdom animalia features 7

• multicellular euk orgs

• able to diff into many diff specialisedd cells that form tissues and organs

• small temporary vacuoles e.g. lysosomes

• no cell walls

• cilia sometimes

• heterotrophs (wide range of feeding mechs)

• wide range of body forms (communication within complex body forms thru nervous system and chem signalling)

what are viruses

microorganisms that can only be seen using an electron microscope

virus features 5

• no cellular structure, acellular

• have no metabolism

• hijack dna replication machinery in host cells

• energy viruses need for replication is provided by respiration in host cell

• not part of the 3 domains.

how are viruses classified

according to type of nucleic acid (RNA or DNA) their genome is made from.

why are there different groups of viruses

in cellular orgs, dna is always double stranded and rna is usually single stranded. however in viruses dna and rna can be both

4 groups of viruses

• dna single stranded viruses

• dna double stranded viruses

• rna single stranded viruses (SARS-CoV-2)

• rna double stranded viruses

dna single strand virus example - virus, host org, disease

canine parvovirus type 2, dog, canine parvovirus

dna double strand virus example - virus, host org, disease

varicella zoster virus (VZV), human, chickenpox and shingles

rna single strand virus example - virus, host org, disease

morbillivirus, human, measles

rna double strand virus example - virus, host org, disease

human immunodeficiency virus, human, aids

communities

when species interact with other species

ecosystem

a relatively self-contained community of interacting organisms and the environment they live in and interact with. (when communities interact with each other and the environment they live in). vary in size and scale and complexity.

flow of energy

occurs within ecosystem where nutrients are recycled

habitat

the place where a species lives within an ecosystem

niche

role that species plays within ecosystem. encompasses where in environment the orgnaism is, how it gets its energy and how it interacts w other species and physical env. how org fits into ecosystem

biodiversity

the study of all the variation that exists within and between all forms of life and looks at the range and variety of genes species and habitats within a particular region

3 diff biodiversity levels:

• no. and range of diff ecosystems and habitats (ecosystem diversity)

• no. species and their relative abundance (species diversity)

• genetic variation within each species (genetic diversity)

why is biodiversity important

for resilience of ecosystems, in that it allows them to resist changes in the environment

ecosystem/habitat diversity

range of different ecosystems or habitats within particular area or region

large no. diff habitats = ___ biodiv

high e.g. coral reef, very complex w many microhabitats and niches to be exploited

1-2 diff habitats = ___ biodiv

low e.g. large sandy deserts as conditions same throughout

species richness

no. species within an ecosystem e.g. tropical rainforest species rich

species diversity

looks at no. diff species in ecosystem and also evenness of abundance across the diff species present.

• greater no. species in ecosystem = more evenly distrib no. orgs in each then greater species diversity e.g. large no. diff species but only 3-4 individuals so not high spec div

why are ecosystems w high species diversity stabler than lower species div

more resilient to env changes e.g. pine forests florida dominated by 1 or 2 tree spcies, if pathogen then whole pop could collapse

genetic diveristy

diversity of alleles and genes in the genome of species as indi may have same genes but not same alleles

how is gen div measured

working out proportion of genes that have more than one form (allele) and how many possible alleles each gene has

why might gen diff/diveristy between pops of same species occur

slightly diff ranges in habitat so subject to diff selection pressures that affect allele frequency in pop

why is there genetic div within single pop of species

helps population adapt and survive when change sin env occur e.g. biotic factors like new predators, pathogens, competition w other species or abiotic factors like temp, humidity, rainfall changes

why is random sampling used 2

• identification and cataloging as well as time are needed to build species list in ecosystem which is possible where species are very large or areas very small

• otherwise, its impossible, so different samples of area taken and used to make estimates of total species no. in area

sampling

method of investigating abundance and distribution of species and populations

2 types of sampling

• random

• systematic

random sampling

positions of sampling points completely random/due to chance and is beneficial because no bias on part of person carrying out sampling that may affect results

systematic sampling

positions of sampling points chosen by person carrying out sampling but possiblity of bias to certain areas or deliberately place quadrats in areas w fewer species (quicker and easier) so unrepresentative of area

when is random sampling best

when sampling area is reasonably uniform w no clear pattern to way species distrib

distribution of species

how its spread throughout ecosystem

abundance of species

no. individuals of that species

how can distrib + abundance of species be assessed 3:

• frame quadrats

• line and belt transects

• mark-release-recapture

frame quadrats: why, what, how, result 4

• used when some ecosystems v complex w large no. diff species of diff sizes, sampling estimates distrib and abundance of species

• quadrats of different sizes used depending on what is being measured and what is most suitable, usually of wood or metal and square shape (same length sides)

• quadrats laid randomly in area to avoid sampling bias (sample area → grid format and each square labelled w number then random number generator used to pick)

• once quadrat laid, abundance of all diff species can be recorded

results from quadrats use

calculate predicted frequency and density of a species within an area

species frequency

probability that species will be found within any quadrat in the sample area

species freq calc

number of quadrats that species was present/total no. quadrats used then x 100

species density

indicates how many individuals of that species there are per unit area

species density calc

no individuals counted across all quadrates/total area of all quadrats

why and how is percentage cover used

• hard to count

• quadrat divided into 100 smaller squares

• no. squares species found in is equivalent to percentage cover in quadrate e.g. 89/100 = 89%

when are line and belt transects used

when investigating species distrib in areas where there are changes in physical conditions (altitude, soil pH, light intesity) as transects can show how species distrib change w diff physical conditions in the area

transect

line represented by a measuring tape along which sample are taken

line transect method 3

• lay out measuring tape in straight line across the sample area

• at equal distances along the tape record the identity of the organisms that touch the line. e.g. every 2m

• produces qualitative data

belt transect method 2

• place quadrats at regular intervals along the tape and record the abundance of each species within each quadrat

• this produces quantitative data

when is mark-release-recapture used

• stationary organisms as difficult w mobile/migrating animals

• used in conjunction w lincoln index

mark-release-recapture method 6

• first large sample taken - as many indi as possible captured/collected, counted and marked in a way that wont affect survival

• returned to their habitat and allowed to mix randomly with the rest of the population

• when sufficient amt of time passed another large sample captured

• no. marked and unmakred counted within samlpe

• proportion of marked to unmark indi is used to calc estimate of pop size

formula for mark-release-recapture

N (pop estimate) = n1 (no. marked indi released) x n2 (no. indi in second sample marked and unmarked) / m2 (no. marked indi in 2nd sample)

correlation

association or relationship between variables

causation

occurs when one variable has an influence on or is influenced by another

scatter graph

used to get a broad overview of the correlation between 2 variables the data points for both variables

what does correlation coefficient r indicate

strength of the relationsihp between variables. can be calc to determine whether linear relationship exists between variables and how strong relat is

perfect correlation

occurs when all of the data points lie on a straight line with a correlation coefficient of 1.0 or -1.0

correlation can be…

positive or negative.

• positive correlation: as A increases, B increases

• negative correlation: as A increases, B decreases

if correlation coefficient is 0…

no correlation between variables

what is pearsons linear correlation

statistical test that determines whether there’s linear correlation between 2 variables

when can pearsons be used

• quantitative data (number counted and numerical value recorded)

• show a linear relationship upon visual inspection

• shows normal distribution

pearsons method

• create scattergraph of data gathered and identify if a linear correlation exists

• state null hypothesis

• use the following equation to work out pearsons correlation coefficient r

pearsons correlation coefficient r

spearmans rank correlation test

used to determine whether there’s correlation between variables

when can u use spearmans

• data not quantitative (abundance scale over count)

• visual inspection of data suggests non-linear correlation

• may not be normally distrib

spearmans method

• create scatter graph and identify possible linear correlation

• state a null hypothesis

• use following equation to work out spearmans rank correlation coefficient r

• refer to a table that relates critical values of rs to levels of probability

spearmans rank correlation

if value calc for spearmans>critical value for n at 0.05 then..

null hypothesis can be rejected = no correlation between 2 variables

simpsons index calculation

simpsons index calc steps

• calculate n/N for each species

• square each of these values

• add them together and subtract total from 1

values of D

can be between 0-1

1=high lvl biodiv

0=low lvl

extinction

when a species comes to an end or dies out. natural biological process

mass extinction events

past where a very large number of species went extinct at one time, rate of extinction during these periods v high caused by major and sudden shifts in environment e.g. ice age or asteroids. earth currently undergoing bc of humans