Module 4 Flashcards
what are the levels of classification?
Domain Kingdom phylum class order family genus species
why do we classify organisms?
to identify species
to predict characteristics
to find evolutionary link
What is a species?
A group of organisms that can produce fertile offspring
why can’t animals like mules produce fertile offspring?
because they have an odd number of chromosomes, so they can’t pair up properly during sexual reproduction
what is the name of the system we use to name organisms with their genus, species
Binomial nomenclature
what are the characteristics of Prokaryotes
unicellular
no nucleus/ membrane bound organelles
ring of DNA
nutrients absorbed/ through photosynthesis
what are the characteristics of protists?
mainly unicellular nucleus and membrane bound organelles some have chloroplasts can sometimes move by flagella can be parasitic, heterotrophic or autotrophic
what are the characteristics of fungi?
uni or multicellular chitin cell wall nucleus and membrane bound organelles no chloroplasts can't move store foo as glycogen nutrients absorbed from decaying material
what are the characteristics of plants?
multicellular chloroplasts and cellulose cell wall nucleus and membrane bound organelles do not move autotrophic store food as starch
What are the characteristics of animals
multicellular no cell wall membrane bound organelles can move with flagella/ contractile proteins heterotrophic food stored as glycogen
what size ribosomes do each of the 3 domains have?
Eukarya- 80s
Archaea- 70s
Bacteria- 70s
What is the difference between Archaea and Bacteria>
Archaea have RNA polymerase with 10 proteins, whereas Bacteria have 5. Archaea also can live in extreme conditions.
what is phylogeny?
Evolutionary relationships between organisms
What is a phylogenetic tree?
A diagram used to represent evolutionary relationships between organisms. They show that different species have evolved from a common ancestor.
How do we find most evidence for phylogenetic trees?
fossils
what is an advantage of phylogeny?
provides a continuous tree, instead of discrete groups
What are the three main pieces of evidence for evolution?
paleontology
comparative anatomy
comparative biochemistry
how do fossils provide evidence for evolution?
The least complex fossils are found in the oldest rocks, showing life became more complex as time passed
We can see similarities in anatomy of fossils to show that closely related animals have evolved from a common ancestor.
How does comparative anatomy provide evidence for evolution?
homologous structures show that many organisms came from the same ancestor and therefore share similar structures, but have evolved to perform different functions
How can we use comparative biochemistry to provide evidence for evolution?
Neutral changes in a molecules structure (has no effect as not in functional group, and therefore isn’t affected by selection pressures) happen regularly. finding the difference between molecules from two species and plotting against the known rate of neutral mutations shows how long ago they last shared a common ancestor
What are the two types of variation?
Interspecific- between species
Intraspecific, between organisms in a species
what are the two causes of variation?
genetic and environmental
what are the genetic causes of variation?
different alleles for the same gene mutations meiosis sexual reproduction chance
when are the students t test and spearman’s rank used?
t test- comparing means of two populations
spearman’s rank- to consider a relationship between two sets of data
what are the three types of adaptations?
anatomical
behavioral
physiological
list some anatomical adaptations
body covering- hair/feathers, shell, waxy cuticle
Camoflague
teeth
mimicry
How is marram grass adapted to its environment?
curled leaves to minimise surface area exposed to air
hairs to trap moist air
stomata sunk into pits
thick waxy cuticle
list some behavioral adaptations
playing dead
courtship
migration
hibernation
What are the two types of behavioral adaptations?
innate and learned behaviour
List some physiological adaptations
poison production
antibiotic production
water holding
what is an analogous structure?
where something from two different organisms carry out the same role, but have very different structures
what is convergent evolution?
where unrelated species begin to share similar traits, due to adapting to similar selection pressures
describe the process of natural selection
Organisms within a population show variation
Organisms whos characteristics are best suited to a selection pressure are more likely to survive and reproduce
Allele for advantageous characteristic more likely to be passed on
Process repeated over time, increasing gene frequency in the population
Over many generations and involving many genes, this can lead to a new species
what are some modern examples of evolution?
MRSA
peppered moths
sheep blowflies
flavobacterium
what are the three different levels of biodiversity?
Habitat
Species
Genetic
What is habitat biodiversity?
The number of different habitats within an area, this generally leads to an increase in species biodiverasity
What are the two types of species biodiversity?
Species richness- number of different species in an area
Species evenness- a comparison of the number of individuals of each species living in a community
What is genetic biodiversity?
The variety of genes that make up a species. Genetic biodiversity within a species can lead to very different characteristics being exhibited. More genetic diversity allows better adaptation to change
What are the two types of sampling?
Random and Non-random
What are the types of non random sampling?
Opportunistic- weakest as not representative. Sample organism that are conveniently available
Stratified-Broken into mutually exclusive strata and sample taken from each strata
Systematic- Can be line transect where taking samples at points along a line, or belt transect, where two parallel lines marked and samples taken of area in between
Why might sampling not be reliable?
Sampling bias- can be accidental or on purpose, can be reduced by using random sampling
Chance- Organisms selected may not be representative of whole population. Can be minimised by larger sample size
How can we sample animals?
A pooter can be used to suck insects in with a mouthpiece
Sweep nets
Pitfall traps
Tree beating
Kick sampling- kick a river bed and use a net to catch organisms flowing down the river
how can we sample plants?
Point quadrat- frame with bar with holes at set intervals. Pin pushed through and anything touching the pin is sampled
Frame quadrats
In what ways can frame quadrats be used to sample plants in a habitat?
Density- counting number of plants
Frequency- How many times a plant is present in a number of trails (65 out of 100 samples contained at least one buttercup, so frequency= 65%)
Percentage cover- estimate by eye
How can we estimate animal population size
Capture-mark-release-recapture
What abiotic factors can we measure and with what sensor?
wind speed- anemometer light intensity- light meter relative humidity- humidity sensor pH- pH probe temperature- thermometer oxygen content- oxygen probe
What are the advantages of using sensors to measure abiotic factors?
Rapid changes can be detected
Human error reduced
High precision
Data stored and tracked on computer
How to we calculate biodiversity?
Simpsons index of Diversity
D= 1-sigma (n/N)^2
Why is it important to conserve low biodiversity habitats?
Because those who live there may be highly adapted to its extreme conditions, and therefore couldn’t live somewhere else
what factors affect genetic diversity?
INCREASE: Mutations Interbreeding between populations DECREASE: Selective breeding Captive breeding programs Cloning Founder effect Genetic bottlenecks Genetic drift
how can we calculate genetic biodiversity
(No. of polymorphic gene loci) / (Total No. of loci)
In what ways do humans affect biodiversity?
Deforestation
Agriculture
Climate change
How does deforestation affect biodiversity?
Directly reduces number of trees in an area
If only one species felled, species diversity reduced
Destroys animal homes and food
Animals may need to migrate if their habitat has been destroyed, which could increase biodiversity of neighboring areas
How does agriculture affect biodiversity?
Deforestation
Removal of hedgerows, which is a habitat for animals
Use of pesticides/herbicides
Monoculture- greatly reduces food sources
How does climate change affect biodiversity?
Melting of ice caps reduces habitats
Rising sea levels could flood land
Higher temperatures leads to more xerophytes
What are the three groups of reasons for maintaining biodiversity?
Aesthetic reasons
Economic reasons
Ecological reasons
What are the Aesthetic reasons for maintaining biodiversity?
Stress relief
Provides inspiration
Enriches our lives
What are the economic reasons for maintaining Biodiversity?
Deforestation can reduce ability to grow crops
Sustainably removing resources (trees for wood)
May lose things of importance before we know they exist (medicines in rainforest)
Monoculture reduces soil quality
Provides protection against abiotic stress (natural disasters and disease, potato famine)
Promotes tourism
Wider gene pool to choose from for genetic engineering to increase efficiency
What ecological reasons are there for maintaining biodiversity?
All organisms depend on each other, so removing one can have a big effect.
Keystone species have a disproportionately large effect on their environment, so they are necessary to maintain
How can human activity increase biodiversity?
Framing, grazing and forest management can actually increase biodiversity
What are the two types of conservation?
in situ- inside the natural habitat
ex situ- outside the natural habitat
How can we manage a wildlife reserve?
controlling grazing restricting human access controlling poaching feeding animals reintroducing locally extinct species removing invasive species halting succession
What ex situ methods can we use to conserve biodiversity?
Botanic gardens
Seed banks- type of gene bank so they can be used if they go extinct
Captive breeding programs- used on endangered animals
Why may organisms bred in captivity not be able to go into the wild?
Diseases- may not have developed resistance
Behaviour- need to learn to search for food etc
Habitat- may not be a suitable habitat for it to live as it would disrupt already existing ones
May be so gentically different from original population they cannot breed
What are three conservation agreements?
IUCN
Rio convention
Countryside stewardship scheme
What does the IUCN do?
publishes red list of threatened animals so countries can work together to protect them
What does the Rio convention do?
Makes countries develop strategies for sustainable development
Makes countries take steps to stop greenhouse gas emissions
Aims to stop fertile land turning to desert
What does the countryside stewardship scheme do?
sustain beauty and diversity of landscape
Improving wildlife habitats
Conserving archaeological and historic features
Restoring neglected land
what are the 4 types of pathogens?
Bacteria
Viruses
Protista
Fungi
How can bacteria be classified?
By their shape
By cell wall
what are some properties of viruses?
non-living infectious agents genetic material surrounded by protein invade living cells All pathogenic some attack bacteria, called bacteriophage
What are some properties of protists?
parasitic
Single celled or cells grouped into colonies
What are some properties of fungi?
often multicellular, but yeast etc are single celled
absorb nutrients
mostly saprophytes (feed on dead/ decaying matter)
Parasitic
stop plants photosynthesising
How to most bacteria damage tissues?
produce toxins, often to break down cell membranes
How to viruses damage cells?
Enters host cell and its genetic material gets into host DNA. New viruses made until cell bursts and viruses spread
What are the 4 plants diseases to know?
Ring rot- bacterial disease that destroys crops, no cure
TMV- virus that damages leaves and reduces yield, no cure but resistant plants exist
Potato blight- Protictist that damages crop, no cure but resistant plants exist
Black sigatoka- Banana disease caused by fungi- reduces yield, no cure
What are the 7 animal diseases to know?
Tuberculosis (TB) Bacterial meningitis HIV/AIDS Influenza Malaria Ring worm Athletes foot
What is TB?
A bacterial disease that damages lung tissue and suppresses the immune system. Both curable (antibiotics) and preventable (hygiene and vaccination)
What is bacterial meningitis?
Bacterial infection which can cause septicaemia. Affects young people and causes rashes. Antibiotics can cure and vaccines can prevent
What is HIV/AIDS?
AIDS is caused by HIV, which targets T helper cells. Destroys the immune system so you are weaker to other illnesses. Passed through bodily fluids. No vaccine or cure but antiviral drugs can be taken to give many years of normal life.
What is influenza?
a viral infection of the ciliated epithelial cells. Leaves you open to a second infection. There is no cure
What is malaria?
caused by a protist, and is a parasite that can either live in mosquitos or humans. No vaccine and limited cures. Best way to prevent it is to control the vector (nets/long sleeves)
What is ring worm?
A fungal disease that affects mammals and makes skin crusty. Antifungal creams are a good cure
What is athletes foot?
A fungal infection that digests moist skin between toes. Antifungal creams are a good cure
what are the two groups of ways of transmission of disease between animals?
Direct and indirect transmission
What are examples of direct transmission?
skin to skin contact exchange of bodily fluids microbes from faeces on hands animal bite sharing needles ingestion (contaminated food/drink)
What are examples of indirect transmission?
Fomites- inanimate objects such as bedding
Droplets in air
Vectors
water can also acts as a vector
What factors affect transmission of disease between animals?
Overcrowded living conditions Poor nutrition Compromised immune system Bad waste disposal Climate change- introduces new vectors/diseases Socioeconomic factors
How can pathogens spread between plants?
Direct contact between healthy and diseased plants Soil contamination- spores in the soil VECTORS: Wind- carries spores Water Animals- insects and birds Humans
What factors affect the transmission of disease between plants?
Planting crops that are susceptible to disease
Overcrowding
Poor mineral nutrition
Damp, warm conditions
Climate change- more wind etc, and more vectors
How to plants use callose to prevent infection?
Within minutes of the attack, it is synthesised and deposited between cell wall and cell membrane
Acts as physical barrier to stop pathogens getting in. Lignin is also added.
Callose also blocks sieve plates and plasmodesmata to stop spread of pathogen
What Chemical defenses to plants have against infection?
Insect repellants Insecticides Antibiotics Antifungal compounds (chitinases) Toxins
What barriers to humans have to keep pathogens out?
Skin covers body and also has microorganisms and sebum
Mucous lines airways, also contains phagocytes
Lysozymes in tears, urine and stomach acid
Coughing, sneezing, vomiting, diarrhoea
How does blood clotting and wound repair work?
When platelets come into contact with collagen in the skin, they secrete substances including
Thromboplastin- an enzyme triggering a cascade of reactions that forms a blood clot
Serotonin- makes smooth muscle in the blood vessels contract, reducing blood flow
New epidermis forms under scab until it is thick enough
How does the inflammatory response work?
Mast cells activated and release:
Histamines- makes blood vessels dilate to create heat and redness, heat makes it hard for pathogens to reproduce. Also makes blood vessels more leaky to make more tissue fluid, causing swelling
Cytokines- attract phagocytes
What does the non specific immune system do to stop pathogens spreading when they are in the body
Fevers
Phagocytosis
What is a fever?
Increases core body temperature to slow pathogen reproduction, and to increase the efficiency of the specific immune system
Describe the process of phagocytosis
Phagocytes attracted to chemicals released by pathogen
Phagocyte recogonises non self antigen, and engulfs pathogen into phagosome
Fuses with a lysosome to form a phagolysosome
Pathogen digested by enzymes
What is the main difference between neutrophils and macrophages?
Neutrophils can engulf a pathogen quicker, but macrophages combine antigens with Major Histocompatibility complex (MHC) and then becomes an Antigen presenting cell (APC).
What is a cytokine?
A cell signalling molecule that informs other phagocytes that the body is under attack.
What is an opsonin?
Chemicals that ‘tag’ pathogens so they can easily be recognised by phagocytes.
What are antibodies?
Y-shaped glycoproteins called immunoglobulins that bind to a specific antigen on a pathogen.
Made of two long polypeptides called heavy chains and two shorter chains called light chains. Held together with disuplhide bridges.
Variable region is the binding site which is specific to the antigen.
Each antibody can bind to two antigens.
How do antigens defend the body?
Act as opsonins so pathogens can be easily ingested
Most pathogens are no longer effective once they are part of an Antigen-antibody complex
Act as agglutinins causing pathogens to clump together to make engulfing easier
What are the two types of lymphocytes and where do they mature?
B lymphocytes mature in the Bone marrow
T lymphocytes mature in the Thymus gland
What are the main types of T lymphocytes?
T helper cells
T killer cells- destroys pathogen with perforin
T memory cells- part of immunological memory. If they meet pathogen again they divide to form T killer cells
T regulatory cells- suppresses the immune system to stop immune response once pathogen has been eliminated. This helps stop autoimmune responses
What are T helper cells?
Have CD4 receptors that bind to antigens on APC. They produce interleukins, a type of cytokine. These stimulate the activity of B cells, which increases antibody production, simulates production of other T cells, and stimulates macrophages to ingest pathogens
What are the main types of B lymphocytes?
Plasma cells- produce antibodies
B effector cells- divide to form plasma cell clones
B memory cells- Remembers specific antigens and causes a rapid response when pathogen met again
Describe the process of cell-mediated immunity?
Non specific macrophages engulf pathogens and turn into APCs
Receptors on T helper cells fit the antigens, which activates T helper cells, and produces interleukins, forming more T helper cells via mitosis.
The T cells can then develop into T memory cells, produce interleukins, and stimulate development of T killer cells
Describe the process of Humoral immunity
T helper cell binds to APC, this is clonal selection, as the cell with the correct antibody is selected for cloning
Interleukins made by T helper cells activates B cells
B cell divides to give clones of plasma cells and B memory cells. This is clonal expansion
Cloned plasma cells produce antibodies that disable antigens, or act as opsonins or agglutinins, this is the primary immune response
Some cells form B memory cells, that produce the correct antibody if infected again, this is the secondary immune response
What is an autoimmune disease?
Where the immune system stops recognising ‘self’ cells and attacks healthy body tissue
What are 3 examples of an autoimmune disease
Type 1 diabetes
Rheumatoid arthritis
Lupus
What are the 4 types of immunity
Natural active- after first infection
Natural passive- antibodies in colostrum for babies
Artificial active- vaccinations
Artificial passive- Antibodies injected for short term
Why are HIV and Malaria hard to find vaccines for?
Malaria protist spends time in erythrocytes so it is protected by self antigens
HIV disables the immune system itself
What is pharmacogenetics?
Using drugs that work with your individual combination of genetics and disease
what is synthetic biology?
Using genetic engineering, we can develop populations of bacteria that can produce drugs that would otherwise be too expensive.
What is selective toxicity?
The property of antibiotics that causes them to destroy bacteria without affecting the metabolism of human cells.
What are the two high profile examples of antibiotic resistance?
MRSA and C. difficile
How can we reduce antibiotic resistance?
Minimising use of antibiotics where possible
Finishing the course
Good hygiene to stop the spread
