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90834 Higher Biology Grade Booster_Flash-Cards.indd 1 03/10/18 4:06 PM

AntiparallelThe two strands of a DNA molecule run in opposite directions and are said to be antiparallel to each other. One strand has deoxyribose (3′)

at one end of the molecule, but its complementary strand has a phosphate group (5′) at the same end of the molecule.

Chloroplast Eukaryotic cells have a small circular chromosome within their chloroplasts.

ChromosomeContains the genetic material of an organism encoded into DNA.

Eukaryotic cells have linear chromosomes in their nuclei and circular chromosomes in their mitochondria and chloroplasts. Prokaryotic

cells have a circular chromosome.

DNADeoxyribose nucleic acid. A double-stranded molecule made up from

chemical units called nucleotides. DNA holds the genetic code in living organisms.

Eukaryotic cellsCells with a nucleus containing their DNA in linear chromosomes

which are tightly coiled and packaged with associated proteins.Mitochondria and chloroplasts in eukaryotic cells have DNA in

circular chromosomes.

Mitochondria Eukaryotic cells have small circular chromosomes within their mitochondria.

Nucleotide Basic unit of DNA consisting of a deoxyribose sugar, a phosphate group and a base.

Plasmids Circular loops of genetic material (DNA) found in prokaryotic organisms and yeast.

ProkaryoticDescribes a cell which has no discrete nucleus. Includes the

bacteria and archaea.Cells contain a circular chromosome and plasmids.

Proteins Large specific molecules made up from chains of amino acids linked by peptide bonds.

YeastYeast are special eukaryotic cells, with linear chromosomes in their

nuclei and circular chromosomes in their mitochondria, but also having plasmids in their cytoplasm.

Structure and organisation of DNACh

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3′–5′ strandThe strand of nucleic acid running from the deoxyribose

sugar to a phosphate.The 3′–5′ leading strand is replicated continuously in the

direction from its 3′ end towards its 5′ end.

DNA polymeraseThe enzyme DNA polymerase adds complementary

DNA nucleotides to the 3′ end of a DNA strand during DNA replication.

heat-tolerant DNA polymerase

The enzyme from hot springs bacteria used in PCR.

Lagging strand The DNA strand which is replicated in fragments and sealed with the enzyme ligase.

Leading strand The DNA strand which is replicated continuously from the 3′–5′ direction.

Ligase The enzyme which joins the DNA fragments on the lagging strand.

Polymerase chain reaction (PCr)

A laboratory technique for the amplification of DNA.

PrimerA short sequence of nucleotides that targets and attaches to a complementary sequence of bases

on the 3′ end of the DNA strands.

replication of DNACh

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Anticodon Sequence of three bases on tRNA which specifies an amino acid.

Codon Sequence of three bases on mRNA which specifies an amino acid.

Exons Sequences of DNA in eukaryotic genes which code for proteins.

Gene expression Genes are transcribed and translated to produce proteins.

Introns Non-coding sequences of DNA in eukaryotic genes.

Messenger rNA (mrNA) Carries a copy of the DNA code from the nucleus to a ribosome.

Peptide bonds Strong chemical bonds between amino acids in a polypeptide chain.

Phenotype Outward appearance of an organism.

Polypeptide Chain of amino acids held together by peptide bonds.

Primary transcript The complementary copy of the base code of a gene made of RNA nucleotides.

ribosomal rNA (rrNA) Type of RNA which, along with protein, makes up ribosomes.

rNA polymerase Enzyme involved in the synthesis of primary transcripts from DNA.

rNA splicing Joining of exons following the removal of introns from a primary transcript.

transcription Copying of DNA sequences to make a primary transcript.

transfer rNA (trNA) Transfers specific amino acids from the cytoplasm to the mRNA on the ribosomes.

translation The synthesis of a polypeptide using sequences of mRNA.

Control of gene expressionCh

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tissue stem cells Stem cells from body tissue which can divide and differentiate to become cells of that type of tissue.

DifferentiationChanges to cells involving switching on certain genes and the switching off of others to produce proteins

characteristic of that cell type.

Embryonic stem cells Stem cells from embryos that can divide by mitosis and differentiate into any type of cell.

Multipotent stem cells Stem cells which can differentiate into nearly any type of cell.

Pluripotent stem cell Stem cells which can differentiate into a limited range of cell types.

research use of stem cells

Stem cells are used to provide information on how cell processes such as cell growth, differentiation and gene

regulation work. They can be used to study how diseases develop OR for drug testing.

Stem cells Undifferentiated cells which can divide by mitosis and self-renew.

therapeutic use of stem cells

Used as part of a medical therapy in the repair of damaged or diseased organs or tissues.

They are used in corneal repair and the regeneration of damaged skin.

Cellular differentiationCh

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Genes Coding sequences of DNA which are transcribed and translated into proteins.

GenomeThe total genetic material present in an organism that can be inherited by its offspring. The genome

includes genes – coding sequences that code for proteins – and non-coding regions.

Non-coding sequencesDNA sequences which do not encode protein. They are transcribed but not translated. They include sequences

that regulate transcription.

the structure of the genomeCh

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Deletion of genes Chromosome mutation in which a sequence of genes is lost from a chromosome.

Deletion of nucleotides

Single gene mutation involving the removal of a nucleotide from a sequence of DNA.

Duplication Chromosome mutation in which a sequence of genes is repeated on a chromosome.

Insertion Single gene mutation in which an additional nucleotide is placed into a DNA sequence.

Missense mutation Single nucleotide substitution that causes a change in one amino acid in a protein.

Mutations Random changes to DNA sequences.

Nonsense mutation Single gene mutation which results in the formation of a stop codon resulting in a shorter primary transcript and protein.

Splice-site mutations Mutations at points where coding (exons) and non-coding regions (introns) meet in a section of DNA.

Substitution Single gene mutation in which one nucleotide is replaced by another.

translocation Chromosome mutation in which part of a chromosome becomes attached to another.

MutationCh

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Allopatric speciation Speciation in which gene flow is prevented by geographical barriers.

Behavioural barrier Barrier to gene flow caused by behavioural differences between individuals.

Deleterious sequences DNA sequences which lower survival rate.

Directional selection Natural selection which tends to favour extreme values of a varied characteristic.

Disruptive selection Natural selection pressure which favours two different values of a varied characteristic.

Ecological barrier Barrier to gene flow caused by ecological preference between individuals.

Evolution Changes to organisms over time which are mainly caused by natural selection.

Geographical barriers

Physical barriers to gene flow such as mountains or rivers.

horizontal inheritance

Inheritance of genetic material within a generation.

Natural selection Non-random increase in the frequency of certain favourable alleles. Process which ensures survival of the fittest.

Speciation Evolutionary process by which new species are formed.

Species Group of similar organisms interbreeding to produce fertile young.

Stabilising selection Natural selection which tends to favour a middle value of a varied characteristic.

Sympatric speciation Speciation in which gene flow is prevented by ecological or behavioural barriers.

Vertical inheritance Genetic material inherited by offspring from parents.

EvolutionCh

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Archaea A domain of life.

Bacteria A domain of life.

Bioinformatics The use of computers and statistics in analysis of sequence data.

Fossil evidence Information derived from the remains of extinct organisms.

Molecular clock Graph which shows differences in sequence data for a protein against time.

Personalised medicine

Ongoing development in which treatment is based on an individual’s genome.

Phylogenetics Study of the evolutionary relatedness of species.

Sequence data Information concerning amino acid or nucleotide base sequences.

Genomic sequencingCh

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Metabolic pathwaysCh

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Activation energy The energy required to start a chemical reaction.

Active site Region on an enzyme molecule where the substrate binds.

AnabolicAnabolic pathways are biosynthetic processes that involve the

building up of complex molecules from simpler substances. Anabolic pathways require the input of energy.

Catabolic Catabolic pathways involve the breakdown of complex molecules into simpler substances. They usually release energy.

Competitive inhibition

Involves competition for the active site of the enzyme by molecules that resemble the shape of the substrate. Competitive inhibition can

be reduced by increasing the substrate concentration.

Feedback inhibition Enzyme inhibition caused by the presence of an end product of a metabolic pathway.

Induced fit Changes to an enzyme’s active site brought about by their substrate.

Metabolic pathways Series of chemical reactions controlled by enzymes.

Metabolism The sum total of all the chemical reactions that take place within a living cell.

Non-competitive inhibition

Enzyme inhibition by a substance that binds to a site on the enzyme other than the active site. It permanently alters the shape of the

active site of an enzyme.

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Cellular respirationCh

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Acetyl group Produced by the breakdown of pyruvate and joins with oxaloacetate to form citrate in the citric acid cycle.

Cellular respiration The release of energy from respiratory substrates.

Citrate The first substance produced in the citric acid cycle.

Citric acid cycle The second stage of aerobic respiration occurring in the matrix of mitochondria.

Coenzyme A The substance which carries the acetyl group into the citric acid cycle.

Dehydrogenase An enzyme which removes hydrogen from its substrates.

Electrons Electrons yield energy as they pass through an electron transport chain.

Electron transport chain

A chain of proteins embedded in membranes of mitochondria and chloroplasts that transport electrons.

FermentationIn the absence of oxygen, the pyruvate undergoes fermentation to either lactate in mammal muscle cells or ethanol and CO2 in plant

cells and in yeast.

Glycolysis The first stage of respiration; involves the breakdown of glucose to pyruvate.

Intermediates Substances in a metabolic pathway between the original substrate and the end product.

Lactate Produced by the anaerobic conversion of pyruvate in mammalian muscle cells.

NAD Coenzyme that transports hydrogen ions and electrons to the electron transport chain on the inner membrane of the mitochondria.

Oxaloacetate Substance which combines with the acetyl group in the citric acid cycle to form citrate.

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Phosphate (Pi) Inorganic phosphate used to phosphorylate ADP to form ATP.

Phosphorylation The addition of phosphate to a substance. The first steps in glycolysis involve the phosphorylation of glucose and intermediate 1.

Pyruvate The end product of glycolysis. Pyruvate progresses to the citric acid cycle if oxygen is available.


Complete double circulation

A double circulation with complete separation of oxygenated and deoxygenated blood. For example, in mammals and birds.

Double circulation Blood flows through the heart twice during a full circulation of the body.

Incomplete double circulation

A double circulation with some mixing of oxygenated and deoxygenated blood. For example, in amphibians and some reptiles.

Metabolic rateThe amount of energy used in a given period of time. It can be

measured in terms of the oxygen consumed, the carbon dioxide produced or the heat produced in the time period.

Single circulatory system

Blood flows through the heart once during a full circulation of the body. For example, in fish.

Metabolic rateCh

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Conformer Animal whose internal environment is dependent on its environment.

Ecological niche The way of life and the role of an organism in its community.

homeostasis The maintenance of a steady state or constant internal environment in the cells of a living organism.

hypothalamusThe temperature-monitoring centre of the mammalian brain. It contains thermoreceptors, which detect changes in blood

temperature.

Negative feedback The control system for maintaining homeostasis in regulator organisms.

regulatorsAnimals that can control their internal environment and maintain

a steady state known as homeostasis by using physiological mechanisms.

thermoreceptors Heat-sensitive cells in the hypothalamus of mammals.

thermoregulation Use of negative feedback in regulation of body temperature in mammals.

Metabolism in conformers and regulatorsC

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Aestivation Type of dormancy which allows animals to survive in periods of high temperature or drought.

Consequential dormancy

Dormancy which occurs in response to the onset of adverse conditions.

Dormancy Reduction in metabolic rate made by organisms to tolerate adverse conditions, e.g. hibernation, aestivation.

hibernation Response of an animal to avoid adverse conditions by reduction of metabolic rate, brought about by low temperatures and lack of food.

Innate behaviour Unlearned instinctive behaviour.

Learned behaviour Behaviour of an individual organism not common to all members of its species.

Migration Movement by an organism to avoid adverse conditions by relocating.

Predictive dormancyDormancy which occurs before the onset of adverse conditions.

Triggered by environmental cues such as temperature and photoperiod.

torporPeriod of reduced activity in organisms with high metabolic rates

such as small birds and mammals. Daily torpor is similar to short-term hibernation.

Metabolism and adverse conditionsC

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Beef extract Complex growth medium for microorganisms.

Death phasePhase of microorganism growth in which death rate of cells exceeds rate of cell division. Lack of substrate and the accumulation of toxic

metabolites cause the death of cells.

Exponential growth Growth phase of microorganisms involving rapid increase in numbers.

Growth medium Microorganisms require an energy source and raw materials for biosynthesis.

Lag phase Phase when the microorganisms adjust to the conditions of the culture by inducing enzymes that metabolise the available substrates.

Log phase Exponential phase of microorganism growth.

Secondary metabolite

Substance produced during the stationary phase of growth of a culture of microorganisms. Substances not associated with growth,

such as antibiotics.

Stationary phase Phase of microorganisms’ growth during which secondary metabolites are produced.

Sterility Not containing contaminating microorganisms.

Environmental control of metabolism in microorganismsC

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Artificial chromosome

Used as a vector to carry foreign genetic information into another cell.

Mutagenesis The process of inducing mutations by exposure to mutagenic agents such as UV) light, other radiation or certain chemicals.

Origin of replication Genes for the self-replication of the plasmid, which is essential for the future copying of the plasmid.

recombinant DNA technology

Involves the joining together of DNA molecules from two different species.

regulatory sequences

Control gene expression.

restriction endonuclease

Enzyme which cuts target sequences of DNA from a chromosome OR is used to open a plasmid.

restriction siteA location on the plasmid that can be cut open by the same restriction endonuclease used to extract the gene from the

donor’s DNA.

Safety genes Genes which are introduced that prevent the survival of the microorganism in an external environment.

Selectable marker genes

Genes present in the vector which ensure that only microorganisms that have taken up the vector grow in the presence of the selective

agent (antibiotic).

Genetic control of metabolism in microorganismsC

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3-phosphoglycerate (3PG)

3-phosphoglycerate (3PG) is phosphorylated by ATP and combined with hydrogen from NADPH

to form glyceraldehyde-3-phosphate (G3P).

Absorption spectrum

Graph showing the wavelengths of light absorbed by a pigment.

Action spectrumGraph showing the wavelengths of

light involved in photosynthesis. The rate of photosynthesis carried out at each wavelength of light.

AtP synthase Membrane-bound enzyme which synthesises ATP.

Calvin cycle Carbon fixation stage of photosynthesis.

CarotenoidsOrange and yellow accessory pigments in plants. Carotenoids

extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis.

Coenzyme NADP Hydrogen carrier in photosynthesis.

Cultivars Varieties of cultivated crops, e.g. high-yielding, disease-resistant, GM cultivars.

Glyceraldehyde- 3-phosphate (G3P)

Compound in the Calvin cycle which can be synthesised into glucose or used to regenerate RuBP.

Food security The ability to access sufficient quantity and quality of food over a sustained period of time.

PestsOrganisms which damage agriculture and reduce food security.

Most of the pests of crop plants are invertebrate animals such as insects, nematode worms and molluscs.

Food supply, plant growth and productivityC

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Photolysis Light energy splits water into oxygen, which is evolved, and hydrogen, which is transferred to the coenzyme NADP.

ribulose bisphosphate (ruBP)

The carbon dioxide acceptor molecule in the Calvin cycle.

ruBisCO The enzyme that fixes carbon dioxide by attaching it to RuBP.

trophic levels Feeding levels in a food chain. Energy is lost between each trophic level.


Bt toxin gene The Bt toxin gene has been inserted into plants using recombinant DNA technology to produce pest resistance.

CrossbreedingBreeding organisms of different genotype together which

may produce a new crossbreed population with improved characteristics.

F1 generation First generation of offspring from a genetic cross.

F2 generation Offspring of an F1 generation.

Field trialsNon-laboratory tests carried out in a range of environments to

compare the performance of different cultivars or treatments and to evaluate GM crops.

Genetically modified (GM) crops

Genetically modified crops which contain gene(s) from other species.

Genome sequencingProcedure to produce the nucleotide sequence of an entire genome. Organisms with desirable genes can be identified and then used in

breeding programmes.

Glyphosate resistance gene

The glyphosate resistance gene has been inserted into plants using recombinant DNA technology to provide herbicide tolerance.

heterozygous Having two different alleles of the same gene and so not breeding true.

homozygous Having two identical alleles of the same gene and so breeding true.

hybrid vigour Crossbreeding can produce F1 hybrids which often show hybrid vigour (increased growth rate, increased yield and disease resistance).

InbreedingCrossing organisms of the same or similar genotype for several

generations until the population breeds true for the desired characteristics.

Plant and animal breedingCh

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Inbreeding depression

An increase in the frequency of individuals which are homozygous for recessive deleterious alleles, which lowers biological fitness.

Plant and animal breeding

Methods of crossing domestic animals and plants to improve characteristics and help support sustainable food production.

randomised Field trials should be randomised to eliminate bias when measuring treatment effects.

recessive Alleles which only show in the phenotype when they are in homozygous form.

recombinant DNA technology

Single genes for desirable characteristics can be inserted into the genomes of crop plants, creating genetically modified plants with

improved characteristics.

replicates Field trials should be replicated to take account of the variability within the sample.

Selection of treatments

The selection of treatments in a field trial must ensure that a valid comparison can be made.

true breeding Homozygous.


Annual plant weedsWeeds that complete their life-cycle in one year.

Rapid growth, short life-cycle, high seed output and long-term seed viability.

Bioaccumulation Build-up of a chemical in an organism.

Biological control Method of controlling pests using natural predators, parasites or pathogen of the pest.

Biomagnification Increase in the concentration of a chemical moving between trophic levels.

Crop pests Organisms which reduce the yield of crops. Mainly invertebrate animals such as insects, nematode worms and molluscs.

Cultural control Methods of crop protection based on human behaviours and activities such as ploughing, weeding and crop rotation.

Disease forecasting Applications of fungicide based on disease forecasts are more effective than treating diseased crops.

Fungicide Chemical substance which kills fungal pest species.

Integrated pest management (IPM)

A combination of chemical, biological and cultural means to control pests.

Perennial weedsWeeds which persist in the community by continuing to grow

year after year. Competitive adaptations include storage organs and vegetative reproduction.

Persistent Unable to be broken down by enzymes.

PesticidesPesticides include herbicides to kill weeds, fungicides to control fungal diseases, insecticides to kill insect pests, molluscicides to

kill mollusc pests and nematicides to kill nematode pests.

Selective herbicides Have a greater effect on certain plant species (broad-leaved weeds).

Systemic herbicides Spread through the vascular system (phloem) of the plant and prevent regrowth.

Crop protectionCh

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Misdirected behaviour

Inappropriate use of normal behaviour, such as over-grooming of feathers by chickens.

Stereotypy Repetitive actions such as aimless chewing movements in pigs.

Animal welfareCh

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hosts Organisms that are harmed by the loss of energy and nutrients to the parasite.

Intermediate (secondary) host

Organism involved in the life-cycle of a parasite separate from the main host.

Mutualism Symbiosis in which both partner species benefit from the relationship.

Parasite A parasite benefits in terms of energy or nutrients, whereas its host is harmed by the loss of these resources.

resistant stagesSome parasites use resistant larvae and pupae, which can survive

adverse environmental conditions until a new host comes in contact with them.

Symbiosis Intimate co-evolved relationship between two different species.

Vectors An organism that carries and transmits the parasite into a new host organism.

SymbiosisCh

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Alliances Links between individuals in primate social groups which are often used to increase social status within the group.

Altruistic behaviour

Behaviour which harms a donor but benefits the recipient.

Appeasement behaviour

Behaviour carried out by subordinate animals to appease a dominant individual and reduce conflict.

Co-operative hunting

Hunting behaviour in which individuals work together to catch prey.

Dominant animal Animal ranked at the top of a social hierarchy.

Donor Organism which carries out the altruistic behaviour to benefit the recipient.

Kin selectionThe donor will benefit in kin selection in terms of the increased

chances of survival of shared genes in the recipient’s offspring or future offspring.

recipient Organism who benefits from the altruistic behaviour of the donor.

reciprocal altruism An altruistic behaviour which is returned by the original recipient to the original donor.

Social hierarchies A rank order within a group of animals consisting of dominant and subordinate members.

Social insects Insects which live in complex social colonies, such as bees, wasps and termites.

Subordinate Animals ranked below the dominant individual.

Social behaviourCh

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Dominant speciesMost abundant species in an ecosystem. A community with a dominant species has a lower species diversity than one with

the same species richness but no particularly dominant species.

Ecosystem diversity

The number of distinct ecosystems within a defined area.

Genetic diversity The number and frequency of all the alleles within a population.

relative abundance The numbers of a species compared with others in a community.

Species diversityThe number of different species in an ecosystem (the species

richness) and the proportion of each species in the ecosystem (the relative abundance).

Species richness The number of different species in an ecosystem.

Components of biodiversityCh

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Bottleneck effect

Inability of a species to evolve due to lack of genetic diversity.

habitat corridors

The corridors allow movement of animals between habitat islands or fragments, increasing access to food and choice of a mate. This may lead to recolonisation of small fragments after

local extinctions.

habitat fragments

Very small areas of isolated habitat.

habitat islands Areas of habitat isolated from other habitats.

Introduced (non-native) species

Species that humans have moved either intentionally or accidentally to new geographic locations.

Invasive species Naturalised species that spread rapidly and eliminate native species, therefore reducing species diversity.

Naturalised species

Species that become established within wild communities.

threats to biodiversityCh

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Accuracy How close a measurement is to its actual value.

Control Technique to ensure that the results of an experiment are caused by the independent variable being investigated.

Dependent variable Variable which forms the data in the results of an experiment.

Independent variable Variable under investigation.

reliability A measure of the confidence in the results of an experiment.

Validity A measure of the fairness of an experiment; how well variables are controlled to allow valid conclusions to be drawn.

Skills of scientific inquiryCh

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