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Terms in this set (343)
The definition of metabolism
The collective term for all the integrated, enzyme-controlled biochemical reactions that occur within a living cell
Big molecules are synthesised from smaller molecules. Requires an input of energy
The breakdown of big molecules to form several smaller molecules. Energy is released in such a reaction
Metabolic pathways can have what?
Reversible and irreversible steps and alternative routes may exist that can bypass steps in a pathway
What are the three functions of proteins within a phospholipid membrane?
Pores, pumps and enzymes
Protein pores within a membrane are involved in what kind of transport?
Passive transport (energy not required)
Active transport requires what?
Examples of abiotic factors
Oxygen, pH, salinity (environmental factors that can affect an organism)
When are alternative routes used in metabolic pathways?
When the cell has a plentiful supply of the substrate
What is the function of lysosomes?
Lysosomes contain digestive enzymes that the cell must be protected from
What feature of small compartments allow high concentration and reaction rates?
High surface area to volume ratio
What can occur to localise the metabolic activity of the cell?
Membranes can form compartments
What term can be used to describe the composition of the plasma membrane?
Describe ways of controlling metabolic pathways
Intra- and extra cellular signal molecules, presence/absence of particular enzymes, regulation of key enzyme reaction rate
What has a low affinity for the active site of an enzyme?
What is the name for a group of enzymes that can work in concert?
What are the three domains of life?
Eukaryotes, bacteria, archea
How are enzymes that are continually expressed controlled?
Through regulation of their reaction rates
What can be done to overcome the effects of competitive inhibitors?
Increasing substrate concentration
An enzyme's active site can be described as what?
Fluid and dynamic
An active site can alter in shape slightly to fit more closely around its substrate. What is this process called?
What effect does an enzyme have on the bonds between reactants?
It weakens such bonds thus lowering the activation energy
Activation energy is lowered by the addition of what?
Molecules which can be broken down to release energy in respiration are called?
ATP is formed from ADP and Pi in what reaction?
When ATP is broken down to ADP and Pi, what is released?
Where do starch and glycogen enter as substrates in respiration?
Converted into glucose for use in glycolysis
Where do fatty acids enter the respiratory pathway?
Converted to acetyl coenzyme A before entering the citric acid cycle
Where does glycerol enter respiration when it's used as a respiratory substrate?
Converted to intermediate molecules for use in glycolysis
Where do proteins enter when used as respiratory substrates?
Broken down to produce amino acids. Converted to pyruvic acid, acetyl co-enzyme A, or intermediates in the citric acid cycle
Fish have what type of cardiovascular system?
How many atria do fish have?
Body tissues of fish receive blood at what pressure?
Low pressure - direct from the gills
Amphibians and reptiles have what kind of cardiovascular circuit?
How many atria do amphibians and reptiles have?
How do amphibians make up for their inefficient gas exchange system?
Oxygen diffuses into the amphibians from the moist skin and mouth cavity
Why is the amphibian gas exchange system inefficient?
The surface area available for diffusion is low, being limited to the outer surface of the lungs
Describe the reptile gas exchange system
Each lung is divided into several alveolar-type sacs, increasing the surface area over which diffusion can take place
Why area alveoli efficient for gas exchange?
Thin walls, good blood supply, large surface area
What are the series of parallel tubes in birds' gas exchange systems called?
Which gas exchange system is the most efficient and why is this important?
Birds. Birds have the highest metabolic rates and therefore require the most efficient way of getting oxygen around the body to maintain their metabolic rates
The bird gas exchange system avoids what?
The unidirectional air flow prevents the mixing of inhaled/exhaled air, maximising the oxygen content of the air. This is important as flight at high altitudes has high metabolic needs in a low oxygen environment
Why are mammals and birds said to have a complete circulation system?
There is no mixing of oxygenated and deoxygenated blood
What is the divide within a reptile's ventricle known as?
Birds have what which lie outside the lungs?
Posterior and anterior air sacs
Describe what happens in the air sacs of birds during inhalation
Fresh air is drawn into the posterior air sacs, while stale air leaves the lungs and enters the anterior air sacs.
Describe what happens in the air sacs of birds during exhalation
On exhaling, the posterior air sacs push oxygen-rich air into the lungs and stale air from the anterior air sacs passes into the trachea and leaves the organism
What is VO2 max?
The max volume of oxygen that a person's body can take up and use during intense exercise
What is Basal metabolic rate (BMR)?
The minimum rate of energy release by an endotherm to maintain essential body processes
What must diving animals cope with on increasing water depth?
Limited supply of oxygen and an increase in pressure
Name 2 low oxygen niches that require organisms to have adaptions
Mammals diving for food, humans living at high attitudes
How does the weddell seal cope in a low oxygen environment?
Its lung collapses reducing buoyancy, heart rate decreases, metabolic rate decreases, blood is diverted to the heart, brain and lungs
How have humans adapted to living at high altitudes?
Higher red blood cell count, increased levels of haemoglobin, increased pulmonary capacity, broader blood vessels
What is physiological homeostasis?
Maintenance of the body's internal environment within certain tolerable limits despite changes in the body's external environment. Result of negative feedback control and requires control
What determines the shape of an enzyme's active site?
Active site of enzyme is determined by the chemical structure of the protein of which the enzyme is made and the bonding between its component amino acids
What are conformers?
Animals that allow their internal body conditions for a particular factor to vary with the external environment.
How do conformers attempt to keep their body's environment at a tolerable level?
Behavioural adaptions - moving to advantageous conditions or by avoiding other less favourable conditions
What can be said about the metabolic rates of conformers?
They have low metabolic costs and narrow ecological niches
Where do conformers usually live?
Stable environments where there is little change to the abiotic factor
What is an ectotherm?
Animals that cannot regulate their own body temperature
What is an endotherm?
Animal that can regulate its own body temperature
Regulators use what to maintain their internal body conditions at optimum levels (homeostasis)?
The maintenance of the body's internal environment in response to changes in the surroundings. This includes water balance, temperature, blood sugar level
What cells detect changes in the set point (where conditions are optimum for body processes)
Which organs respond to messages about deviations from the set point?
Effectors - muscles and glands
Messages sent out to effectors by the monitoring centres can be in the form of what?
Hormones that are secreted into the blood, nerve impulses
All chemical reactions in the body are controlled by what?
What is the temperature monitoring centre in the brain known as?
What is the name for receptors that detect blood temperature?
What is vasoconstriction?
Constriction of skin arterioles diverts blood away from the skin's surface, reducing heat loss by radiation - warming up effect
What is the name for the process when skin arterioles dilate to divert more blood to capillaries at the skin's surface, increasing heat loss by radiation? What effect does it have on body temperature?
Vasodilation - body temperatures decreases
Increased sweat production occurs to enable what?
Sweat to evaporate from skin surface thus lowering body temp
What to erector pili muscles do to contain heat?
Contract so body hairs are in a raised position that traps air to insulate the body
When the body temperature is above the normal level, what happens to the erector pili muscles?
They relax, allowing body hair to lie flat against the skin which minimises the insulating effect
What is the name for shivering?
Involuntary muscle-skeletal contractions
Metabolic rate does what to increase body temperature?
What happens, in physiological terms, to an animal during hibernation?
Lowering of body temp, heart and breathing rates decrease,, oxygen consumption decreases. This lowers the metabolic rate - the animal uses up its body fat reserves as an energy source
Name the 3 native British mammals that hibernate
Dormouse, bat, hedgehog
Define daily torpor
Short periods on a daily basis when body temperature, heart and breathing rates, and oxygen consumption are lowered. This conserves energy - common in small animals with high metabolic rates
What is aestivation?
Similar to hibernation but takes place during long periods of extremely high temperatures or extremely dry conditions, when food and water may be scarce
Which requires more energy; hibernation or aestivation?
What is the difference between predictive and consequential dormancy?
Predictive dormancy - when the organism enter dormancy before the adverse conditions begin. Consequential dormancy - when the organism enters dormancy after the adverse conditions begin
Is migration avoiding or surviving adverse conditions?
What mechanisms trigger migration?
changing day length, temperature, changes in food availability, and genetic factors
What methods are used to track migrating animals?
Radio/satellite tracking, tagging, direct observation
What is innate behaviour?
Inherited and is carried out by all individuals in a species. Triggered by an external stimulus and is inflexible
What is learned behaviour?
Develops as a result of experience - through watching other or by trial and error. It is flexible
Migration is influenced by what kind of behaviour?
Both innate and learned
What are extremophiles?
Organisms (usually archea) that live in extreme environments in which other organisms could not survive
What enzyme is found in thermophilic bacteria that live in hot springs, and what is its use?
Taq polymerase - used in PCR as it is heat tolerant
How do some extremophiles generate ATP?
By removing high-energy electrons from inorganic molecules
Definition of migration
The regular movement of a species from one place to another. They avoid metabolic adversity by expending energy to relocate to a more suitable environment
What is another name for lactate and what process results in its production?
lactic acid - produced by the reversible fermentation pathway in animals. This pathway occurs in the absence of oxygen and an oxygen debt is accumulated
What culture conditions to microbes grown in the lab require?
Appropriate temperature, pH and oxygen levels. Raw materials for synthesis of molecules. Some organisms require complex compounds such as vitamins and fatty acids. A source of energy is required if the organism cannot photosynthesise
Growth media can be in what form?
solid or liquid
Microbes grown for industrial purposes are grown in what?
Industrial fermenter vessels
What is added to a liquid medium that causes it to solidify?
What is a defined media?
The chemical composition of the medium is known and is in a relatively pure form
What is a complex media?
The exact chemical composition of nutrients in this media is 'undefined' or unknown, because the source of amino acids is a complex meat or yeast extract
What is used to maintain sterility?
Aseptic techniques are used to eliminate any unwanted, contaminating microorganisms that would affect the growth of the desired organism
How is oxygen concentration controlled in a fermenter vessel?
Filtered air is bubbled through liquid media (aeration) to provide oxygen for aerobic microorganisms in fermenter vessels
How is an optimum pH of the culture media maintained?
Through the addition of buffers or addition of acids/alkalis. Most bacteria grow better in media of pH7. Fungi usually prefer pH5-6
In what stage of microbial growth are enzymes induced?
What are the 4 phases of microbe growth?
Lag, log/exponential, stationary and death phase
What happens in lag phase?
Cell numbers increase very slowly, if at all. The cells prepare for division by synthesising components such as nucleic acids and enzymes
What does the length of lag phase depend on?
The level of damage or 'shock' that the cells must recover from and the time required to synthesise new molecules
What is the generation time?
Time taken for the population of microbes to double in size
Why does the number of microbes remain constant during stationary phase?
The birth rate and death rate equalise
Why does dividing rate decrease in stationary phase?
Essential nutrients in the culture medium are depleted and toxic waste products (metabolites) accumulate
What are secondary metabolites?
Molecules that are not required for cell growth but which may give the cell an ecological advantage
What does an action spectrum graph show?
The rate of photosynthesis at different wavelengths of light
Green plants use light energy from the Sun to produce what?
Why are accessory pigments important?
They increase the energy available for photosynthesis by absorbing different wavelengths of light
Where do accessory pigments pass their absorbed energy to?
Name the 2 accessory pigments and their broader name
Xanthophyll & carotene - broadly known as cartenoids
What happens to light energy that is not absorbed by plant pigments?
It is reflected or transmitted
Where can plant pigments be found?
In the grana of chloroplasts
Where do non-competitive inhibitors bind?
Allosteric sites (non active sites on a an enzyme)
What causes an increase in death rate over the rate of cell production?
Lack of food/oxygen and the build-up of toxic metabolites
What is total cell count?
The number of both living and dead cells present in the sample
Define viable cell count
The number of cells that are alive and able to grow in a sample
What enzyme is used in the electron transport chain to catalyse ATP production?
What enzyme fixes RuBP to CO2 in the calvin cycle?
Glycolysis is the first stage of what process? Where does it take place?
Respiration - its takes place in the cytoplasm
What occurs in the energy investment stage of glycolysis?
2 ATP molecules are used to phosphorylate intermediates
What is the net gain of ATP in glycolysis
2 ATP molecules
What 2 coenzymes transfer hydrogen ions in respiration?
NAD & FAD
FAD coenzyme A is only active in what stage of what process?
The citric acid cycle - 2nd stage of respiration
What follows the formation of citrate in the citric acid cycle?
The enzyme mediated steps of the cycle
What is produced by the citric acid cycle?
Generation of ATP, release of CO2, and the regeneration of oxaloacetate
Where does the citric acid cycle take place?
Matrix of the mitochondria (inner cavity)
CO2 and ethanol are the products of what plant metabolic pathway ?
Why can the electron transport chain be described as a multi-enzyme complex?
It is a collection of proteins attached to a membrane (the inner membrane of the mitochondria)
What is the name of the enzymes that remove hydrogen ions and electrons?
What is the role of oxygen in the electron transport chain?
Acts as the final electron acceptor, combining with hydrogen ions and electrons to form water
What happens to high energy electrons in the electron transport chain?
Release energy as they pass down the chain, allowing hydrogen ions to be pumped across the inner membrane against the concentration gradient. Combine with oxygen and hydrogen ions to form water
Starch and glycogen are broken down to what substrate for use in respiration?
Other sugars are broken down to what in order to be used as a respiratory substrate?
Glucose or glycolysis intermediates
Fats and proteins can be broken down to what for use in respiration?
Intermediates of glycolysis and the citric acid cycle
What are the ways to measure metabolic rate?
Co2 production, heat production, O2 consumption
High metabolic rates require what?
Efficient delivery of oxygen to cells
What is another name for fermentation?
VO2 max is a measure of what?
Conformers internal environment is dependent upon what?
Their external environment
Conformers have a narrow what?
Why do conformers usually live in the ocean?
Provides a stable external environment
Regulators use metabolism to what?
Control their internal environment
Why is temperature regulation important?
To maintain optimal enzyme controlled reaction rates and diffusion rates to maintain metabolism
Dormancy can be either what or what?
Predictive or consequential
What experiment can be done to test whether migration is an example of innate or learned behaviour?
Put young and old birds off course to see if they make it to their destination
Micro-organisms are from what domain of life?
Bacteria, archea and some species of eukaryota
Which phase of microbe growth is enzyme induced?
What substances produced by microbes are not associated with growth?
What are the draw-backs of mutant strains? What often happens to them in continuous culture?
Typically genetically unstable and revert to the wild type in continuous culture
What is mutagenesis?
Exposure to UV light and other forms of radiation or mutagenic chemicals results in mutations some of which may produce an improved strain
What is the name of the enzyme that cuts specific sequences of DNA leaving sticky ends
Some bacteria can transfer plasmids/pieces of chromosomal DNA to each other or take up DNA from its environment by what process?
Wild strain of microbes can be improved by?
mutagenesis, selective breeding and culture, recombinant DNA
What enzyme seals target sequences into plasmids?
What term can be used to describe the role of a plasmid in recombinant DNA technology?
How many genes to plasmids typically carry?
In which cells can vectors be found?
Most bacteria and some fungi
What other genes apart from the target sequence are added to a recombinant plasmid?
Marker genes (GFP, antibiotic resistance), Self-replication genes, regulatory sequences, safety mechanism (prevent microbes surviving in external environment)
Why are recombinant yeast cells sometimes used in favour of bacteria?
Bacterial cells cannot carry out Post-translational modifications so if a complex protein is required, recombinant yeast cells are a better option
Restriction endonucleases are enzymes that recognise what?
Specific nucleotide sequences on a DNA molecule
Why is it important to cut the target sequence and plasmid with the same restriction endonuclease?
The same restriction endonuclease will always produce DNA fragments with the SAME sticky ends. These fragments can be brought together and sealed by ligase as they will be complementary
Arguments for use of microbes
Cheap, doesn't create toxic by-products, safe
Arguments against use of microbes
Production of biological weapons, may escape and be infectious, shouldn't be in the hands of companies
Define food security
The ability of human populations to access food of sufficient quality and quantity
It is important that food production is what?
Sustainable and does not degrade the natural resources that are vital to agriculture
How is the environment being damaged?
Global warming, pollution, deforestation, soil erosion, reducing soil fertility
Examples of plant crops
Cereals, potatoes, root vegetables, legumes
Factors which limit plant growth
Co2 concentration, light intensity, temperature, availability of nutrients, pests and disease, competition
Name some intensive farming practices
Growth of high yield cultivars, fertilisers, pesticides
What undesirable effects can herbicides/pesticides have?
They reduce biodiversity
Why do livestock produce less food per unit area?
Due to energy loss between trophic levels
Why is heat lost between trophic levels?
Undigested food and waste, maintaining body temp, movement
Define action spectrum
Shows the rate of photosynthesis at different wavelengths of light
The energy captured by accessory pigments is passed where?
To chlorophyll a
Two stages of photosynthesis
Light dependant stage, calvin cycle
Energy released by the high energy electrons in photosynthesis is used to what?
Generate ATP (by ATP synthase), photolysis (splitting of water)
What happens to the products of photolysis in photosynthesis?
Oxygen is a by-product (diffuses out of the cell), Hydrogen binds to coenzyme NADP to form NADPH
Where does the light dependant stage of photosynthesis take place?
In the grana of chloroplasts
Where does the calvin cycle take place?
The stroma of chloroplasts
CO2 attaches to RuBP to form what?
What happens to 3PG to form G3P?
Phosphorylated by ATP and joins with hydrogen from NADPH to form G3P
What happens to G3P after the calvin cycle?
Used to regenerate RuBP or synthesise glucose
What happens to the glucose produced by photosynthesis?
Converted to starch (storage), cellulose (structural), respiration, passed to other biosynthetic pathways
Define plant productivity
The rate of production of new plant material per unit are per unit of time
Define net assimilation
The increase in mass due to photosynthesis minus the mass lost due to respiration
Define biological yield
The total biomass of the plant
Define economic yield
The mass of the desired product
Define harvest index
the dry mass of economic yield/dry mass of biological yield x100
Single gene inheritance show what kind of variation?
Polygenic inheritance characteristics show what kind of variation?
What is a cultivar?
A cultivar is a plant that has been created or selected intentionally for desirable characteristics that can be maintained by cultivation
What are plant field trials used for?
To see whether or not a particular treatment makes a difference to the crop
Plant trials evaluate what?
Performance of different cultivars, performance of different treatments, GM crops
Reliable and valid field trials require?
Careful selection of treatment (other variables kept constant), randomisation, replicates
Define inbreeding depression
The accumulation of deleterious homozygous alleles increasing the chances of offspring being affected by recessive traits because of inbreeding
Inbreeding promotes what?
What can inbreeding depression result in?
Loss of vigour, poor general health, reduce size, fertility and yield
Why are self-pollinating plants less susceptible to inbreeding depression?
Natural selection has eliminated deleterious alleles over many generations
What is carried out to prevent inbreeding depression?
Parents have a different but desired genotype creating offspring with traits from both parents, improving characteristics and producing organisms with hybrid vigour
What is an F1 hybrid?
Offspring of two parents that have a different but desired genotype. F1 hybrid has traits from both parents, improving its characteristics
What is the problem with an F2 generation?
Have a wide range of genotypes
How is a preferable genotype maintained?
By backcrossing and a selection process. Having 2 parent breeds is useful
What is mutation breeding?
Exposing seeds to chemicals or radiation in order to generate mutants with desirable traits to breed with other cultivars
Why is a test cross conducted?
To determine the genotype of an individual with a dominant phenotype - to find out if its heterozygous or homozygous
How is a test cross carried out?
Organism of unknown genotype is crossed with an organism that is homozygous recessive for the same characteristic
What is an inbred line?
When a desired plant is self-pollinated over several generations to create identical plants
What is the problem with F1 hybrid seeds?
What is genomic sequencing?
A process which can determine the DNA sequence of an organism's genome
What is genetic transformation?
The alteration of the genome of a cell by the insertion of a gene from another organism
Example of genetic transformation in crops?
Two genes for beta carotene inserted into rice genome to make a precursor of vitamin A. Vitamin A made in the body after digestion. Golden rice is therefore higher in vitamin A
Describe an annual weed
High seed output, long seed viability, short life-cycle, fast growth, can germinate at low temperatures
Describe a perennial weed
Persistent weeds, dormant during winter, vegetative reproduction, have storage organs, modifications of the stem
3 examples of pests
nematode worms, molluscs, insects
Pests can sometimes be a what for diseases?
The control of weeds, pests and diseases is vital to ensure what?
Examples of cultural control to prevent pests/weeds/disease
Crop cover, crop rotation, pulling out weeds, ploughing, planting dense populations,
Examples of chemical control to prevent pests/weeds/disease
What is a selective pesticide?
Removes only certain types of pests, leaving others unharmed
What is a non-selective pesticide?
Kills a wide range of pests
What should be used to control weeds in a field of a particular crop?
Selective weed killer
What is a contact pesticide?
Destroys any plant/animal tissues they come into contact with. Do not destroy underground vegetative structures
What is a systematic pesticide?
Moves within the plant via the xylem/phloem. Kills the whole plant. Can kill animals when they suck phloem tissue
What is the most effective way to prepare for diseases
What is biological control?
A way to reduce numbers of pests using their natural enemies - predator, parasite, pathogen.
What are the risks of biological control?
non-target insects may be harmed, the control species becomes a pest
What is the name for the process for controlling pests while minimising any risks to other organisms, including humans and the environment
Integrated pest management
What is the last resort of integrated pest management?
Use of pesticide
What is important in IPM?
Long-term pest prevention, forecasting, using a combination of control methods
Repetitive behaviour that serves no obvious behaviour and is constant in form
What is anthropomorphism?
The attribution of human characteristics to non-human beings
What is a preference test?
An experiment where an animal has a choice of condition and shows which condition the animal prefers. Scientists can use a T or Y maze with different options available at the ends of the maze. Their choices are counted over a number of tests
What is the name for the study of animal behaviour?
What is an ethogram?
List of typical species behaviours - collected by observation.
What does an ethogram allow?
Allows the most favourable environments for different species of domesticated animals to be identified
What is symbiosis?
An intimate relationship between organisms from two different species
What are different types of symbiosis
Explain, in terms of the donor host and parasite, the effect of parasitism
The donor is harmed while the parasite benefits from the relationship
Why can parasites not usually live without a host?
They have a limited metabolism, they need to live in or on a host organism
What are the 3 ways that parasites can be transmitted from host to host?
Vector, direct contact, resistant stages
What is meant by resistant stages?
Some parasites have resistant or resting stages which can resist drying out and other stresses such as temperature extremes and hard chemicals
What is a secondary host?
A secondary or intermediate host is necessary for some parasites to complete their lifecycle. Humans are the secondary host for malarial parasites
What is a vector in parasite context?
An intermediate organism that transfers a parasite from one host to the next
A form of symbiosis which benefits both species involved
What organelles in the cell are thought to have evolved from free living bacteria which were engulfed by other cells, forming a mutualistic relationship
What is the evidence for chloroplasts and mitochondria once being free living bacteria?
What is social hierarchy? What does it achieve?
Determines access to food and a mate. Social order exists. Reduces fighting and aggression, conserves energy and prevents injury. The more dominant males will pass their genes to the next generation
What is cooperative hunting?
When a group of animals work together to gain food; this occurs in several species including whales, lions, wild dogs, hyenas and chimpanzees
What are the advantages of cooperative hunting?
Increase in hunting success rate, bigger prey brought down, more efficient kill, subordinates may gain more food than by foraging alone
Examples of social defence behaviours?
group organisation ensures a lookout is always available, mob or attack a predator together, move as a herd, travel in groups, have danger signals
What is altruistic behaviour?
A behaviour which benefits the recipient but harms the donor
Define kin selection
Altruism is common between kin. Natural selection will favour behaviour that increases the survival of relatives. The donor benefits in terms of the increased chance of survival of shared genes in the recipient's offspring
What is reciprocal altruism?
A type of altruism in which the roles of the donor and recipient later reverse
Describe social insects and associated kin selection
The majority are workers who labour together to raise their relatives. Only some individuals in the colony contribute reproductively.
What is a keystone species?
Those which have a particularly important impact on their ecosystem. Without keystone species, the species diversity of the ecosystem would decrease and the ecosystem may cease to exist
Those which benefit humans and are of economic importance are said to provide what?
Ecosystem services. Include decomposers, pollinators and parasitic wasps
Examples of keystone species
Honey bees, wasps, termites, ants
Why are termites considered keystone species?
Build mounds which provide habitats for other species; provide protein-rich food for many animals; are decomposers, so recycle soil nutrients
What does the long period of parental care give primates?
An opportunity for the young to learn complex social behaviours by watching and copying others
What does the social structure of each species depend on?
Its particular ecological niche, the distribution of its resources, the taxonomic group to which it belongs
Dominance hierarchies in primates achieve what?
Help keep order, avoid injury and expending energy
Name 3 common primate behaviours
Forming alliances, appeasement behaviours, ritualistic behaviours
Why do primates form alliances?
To boost or maintain their social status
What are examples of ritualistic behaviour?
Used to communicate in reproductive or agonistic situations. Subordinate and dominate behaviour may be displayed
The variety of living things on earth
Define mass extinction
A rapid decrease in numbers of species on Earth - 25-70% of all species may cease to exist over a period of tens of thousands of years
What is the evidence for mass extinctions?
Which extinction is currently ongoing?
What does a mass extinction leave?
Unfilled niches and the surviving organisms may take advantage of these
What follows a mass extinction?
A period of recovery as biodiversity is slowly regained
Humans are responsible for the extinction of what?
The background extinction measures what?
How often extinctions happen naturally without the interventions of humans
What has contributed to the extinction of mega fauna?
Humans and climate change
The main causes of ecosystem degradation by humans are?
Deforestation, pollution, over exploitation of resources, destruction of habitats
The 3 measurable components of biodiversity?
Species, genetic and ecosystem biodiversity
Define genetic diversity
The number and frequency of alleles in a population. The total genetic variability or the total number of genetic characteristics of a species
Define species diversity
A measure of the number of different species in an ecosystem (the species richness) and the proportion of each species (relative abundance)
Define ecosystem diversity
The number of distinct ecosystem within a defined area. The more remote and isolated at habitat island, the lower its species diversity
The harvesting of a natural resource, for example forests for timer and animals such as fish for food
Ecosystem degradation threatens what?
The survival of many species
What is the bottleneck effect?
A population bottleneck occurs when a population reduces sharply in number, as a result of disease/fire/drought. The remaining organisms within the population lack genetic variation. Rare alleles are now common in the new population. The lack of variation means the whole population will be susceptible to any change in environmental condition
What does habitat fragmentation cause?
A decrease in species richness (reduced biodiversity)
What can fragmented habitats be linked by?
Define indigenous population
One which is native to particular ecosystem and is present naturally without human intervention
Define naturalised species
when a non-native species spreads within wild communities, becomes established and can maintain its population through reproduction
What is an invasive species?
Naturalised species which can spread rapidly and eliminate native/indigenous species. They can have a negative impact on their new environment
What is a gene?
Region of DNA that codes for the specific sequence of amino acids that forms a polypeptide chain
What are the two main categories of organism?
Prokaryotes & eukaryotes
Describe a prokaryote
No membrane bound nucleus, DNA is in circular chromosomes which are free in the cytoplasm. Can contain plasmids
Describe a eukaryote
Membrane bound nucleus, linear chromosomes, have other membrane-bound organelles such an mitochondria and chloroplasts
Prokaryotes do not contain what?
Nucleus, chloroplasts, mitochondria
DNA is wrapped around what?
Chloroplasts and mitochondria have their own what?
DNA must replicate before what process?
What are the requirements for DNA replication?
Primers, DNA template, free nucleotides, DNA polymerase, ATP, ligase
Primers must be what to the DNA template?
Which end of DNA are nucleotides added to?
What is the direction of DNA replication
5' to 3' direction
Name the term used to describe DNA replication
What are the 2 strands in DNA replication called?
Leading and lagging stand
Which strand is replicated in okazaki fragments?
What is PCR used for?
To amplify target sequences of DNA
What are the requirements for PCR?
Target DNA template, thermal cycler, heat-tolerant DNA polymerase, primers, nucleotides, buffer solution
What initiates the activity of DNA polymerase?
Uses of PCR
Forensics, research, phylogenetics, early detection of infection
3 stages of PCR
denaturing, annealing, extension
Annealing temperature is dependant on what?
The target DNA sequence
What temp is denaturing?
Around 95 degrees. The DNA strand unwinds and unzips
What are the differences between DNA and RNA?
A triplet of bases is known as what?
What is the name of the transcript that is a result of RNA splicing?
Mature mRNA transcript
The primary mRNA transcript contains what?
Both introns and exons
Introns are what?
Non-coding sections of DNA
Exons are what?
Coding sections of DNA
What is the role of non-coding DNA
To regulate transcription, transcribed to form RNA but never translated into protein, junk DNA
A mature RNA transcript contains only what?
Where does translation take place?
In the ribosome
What exists at the start and end of the poly-peptide chain?
start and stop codons
Translation is initiated by what?
The start codon
Each tRNA molecule attaches to a what amino acid?
tRNA molecules have a what?
anticodon which is complementary to a codon
Examples of PTM's
Addition of carbohydrate,phosphate. Cleaving and combining of polypeptide chains
What happens during differentiation?
Some genes are switched off, genes that are vital to all living cells are expressed, genes for the specialist function of the cell are expressed
Unspecialised regions in plants
Meaning of totipotent
Can differentiate into any type of cell
Another name for body cells
Where are apical meristems located?
In the tips of roots and shoots
Where are lateral meristems located?
In the cambium layer between xylem and phloem tissue
What are stem cells?
Undifferentiated cells that can divide to form specialised cells
Can form all types of specialist cell
Why are adult stem cells described as multipotent?
They can produce a limited number of cells
Where are adult stem cells located?
In specific locations
What are iPS cells
Adult cells reprogrammed back to pluripotency by added factors that alters the switching off of genes
Therapeutic value of stem cells
Skin grafts, bone marrow transplant, cornea repair
What is the name for a random change to genetic material?
What is a splice-site mutation?
Primary transcript is spliced wrong so introns may exist in the mature transcript. Can alter the function of the protein
Examples of single gene/point mutations
Substitution, insertion, deletion
Why are insertion and deletion mutations more harmful than substitution mutations?
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Higher Biology UNIT 1
Higher Biology: Unit 2
Higher Biology: Unit 3
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