Definitions Flashcards
When is a measurement valid?
When it measures what it is supposed to be measuring
What is repeatability?
How precise repeated measurements are when when they are taken by the same person using the same equipment under the same conditions
What is reproducibility?
How precise repeated measurements are when they are taken by different people using different equipment
What is the uncertainty of a measurement?
The interval within which the true value is expected to lie
Define measurement error
The difference between a measured value and the true value
What type of error is caused by results varying around the true value in an unpredictable way?
Random error
What is a systematic error?
A consistent difference between the measured values and the true values
What does zero error mean?
A measuring instrument gives a false reading when the true value should be zero
Define a fair test
A test in which only the independent variable is changed
what is a null hypothesis?
States there is no significant difference between two populations
Continuous variation
Data that can take any value on a sliding scale e.g height, mass
Discontinuous variation
Data can not be sorted into discrete categories
Interspecific variation
Differences between organisms of difference species
Intraspecific variation
Differences between organisms of the same species
What is a normal distribution
A normal distribution in graphs has a bell shaped curve which is symmetrical (Mean, median and mode are equal)
What is suspension?
A mixture in which particles are dispersed throughout the bulk of a fluid.
What does the term Degenerate mean in terms of Genetic code?
An amino acid may be specified by more than one type of codon (A set of three adjacent nucleotides in mRNA)
What does the term ‘non-overlapping’ mean in terms of genetic code?
Each base in the sequence is read only once
What does the term universal mean in terms of genetic code?
Each triplet codes for the same amino acid in all organisms.
Definition of a gene?
A sequence of DNA which codes for a polypeptide
Codon
Three bases that code for a specific protein.
Introns
Left over combinations; do not code for proteins.
Locus
A particular position on a particular chromosome where a gene sits.
Histone
The protein that DNA coils around to fit in a cell. Together these form chromatin (what chromosomes are made of)
Alleles
Different versions of genes
Homologous chromosomes
Two chromosomes that carry the same genes but not necessarily the same alleles of the genes.
Sister chromatids
Two copies of the same chromosomes held together by the centromere.
Chromatid
One copied section of DNA
Apoptosis
Cell death
Pathogens
Disease causing microorganisms
Genome
Complete set of genes in a cell
Proteome
Full range of proteins a cell can produce
Locus
Location of a gene
When a genetic code is degenerate
More than one triplet codes for the same amino acid.
(This reduces the number of mutations caused by substitution, deletion and insertion)
Histones
Proteins in eukaryotic cells to form structures called chromosomes.
This is the result of the DNA being tightly compiled around the histones.
Introns
A segment of a DNA or RNA molecule which does not code for proteins
Exons
A segment of a DNA or RNA molecule containing information coding for a protein.
Polyploidy
An individual has three or more sets of chromosomes instead of two
Non-disjunction
Occurs when chromosomes fail to separate correctly in meiosis
As a result the gametes will have one more or one less chromosome than they should
Genetic diversity
Total number of different alleles in the population
Population
Defined as a group of individuals of the same species that live in the same place and are able to breed
Niche
The species role within the environment
Natural selection
The process in which fitter individuals who are better adapted to the environment survive and pass on there advantageous genes to future generations by reproduction.
Directional selection
Occurs when the environmental conditions change and the phenotypes best suited to the new conditions are more likely to survive. As a result these individuals will breed and produce offspring.
Stabilising selection
The phenotypes with successful characteristics are preserved and those of greater diversity are reduced. This selection does not occur due to changes in the environment. The furthest from the mean are selected against.
Anatomical adaptations
Physical adaptations either external or internal
behavioural adaptationos
Changes in behaviour which improve the organisms chance to survive
Physiological adaptations
Processes inside an organisms body that increases its chance of survival e.g. regulation of blood flow through the skin
Diploid
A cell with a full set of chromosomes
Haploid
A cell with no pairs of homologous chromosomes so an odd number of chromosomes
Homologous chromosomes
Pair of the same chromosome.
Genes are the same but the alleles are different
Sister chromatids
The copy
(Half old, half new)
Species richness
Number of different species in a community
Genetic bottleneck
An event that causes a big reduction in a population and reduces genetic diversity.
Founder effect
The reduction in genetic diversity that occurs when just a few organisms from a population start a new colony.
