Topic 1- Classification, Variation and Inheritance Flashcards
To revise the keywords for B1 Topic 1.
Allele
Different versions of the same gene, e.g. Allele for Blue eyes or Green eyes.
Adaptation
Organisms have certain characteristics that allow them to survive in particular places. These characteristics are called adaptations.
Autotrophic
Can make food from small molecules e.g. photosynthesis.
Bacteria
Single-celled organism that does not have a nucleus (Prokaryote kingdom).
Amphibians
One of the five kingdoms- moist permeable skin, lay eggs (oviparous) and is a poikilotherm.
Binomial system (Higher)
System of naming organisms using two Latin words- from Genus and Species names.
Species
Groups of organisms that have many features in common. Can interbreed to produce fertile offspring.
Genus
Contains several species with similar characteristics.
Family
Comprising of several genera.
Order
Comprising of several families.
Class
Comprising of several orders, e.g. Mammals, Reptiles…
Phylum
Comprising of several classes, e.g. Chordata.
Kingdom
Top five groups of the classification system.
Animalia
Animals are multicellular, do not have cell walls, do not have chlorophyll, feed heterotrophically (heterotrophs can’t make their own food).
Plantae
Are multicellular, have cell walls, have chlorophyll, feed autotroprically (autotrophs can make their own food).
Fungi
Multicellular, have cell walls, do not have chlorophyll, feed saprophytically (saprophytes feed off dead organisms and decaying material).
Protoctista
Unicellular (single celled), have a nucleus, protoctista include algae.
Prokaryotes
Unicellular (single celled), have no nucleus e.g. bacteria.
Viruses
Smaller than bacteria, cannot reproduce themselves, have protein coat containing a few genes, they invade cells and make them reproduce the invading virus.
Chordata
Animals with a supporting rod running the length of the body, an example of this being the backbone in vertebrates.
Vertebrates
Vertebrates are divided into five classes, groups of amphibians, birds, fish, mammals and reptiles.
Internal fertilisation
Fertilisation inside the body.
External fertilisation
Fertilisation outside the body.
Oviparous
Lays eggs.
Viviparous
Gives birth to live young.
Homeotherms
Warm blooded- can control their own body temperature.
Poikilotherms
Cold blooded- body temperature is affected by surroundings.
Hybrid (Higher)
An organism produced as a result of two different species interbreeding. Will have characteristics of both.
Extremophiles
May be tolerant to high levels of salt, high temperatures or high pressures.
Ring species (Higher)
A group of related populations that live near each other, neighboring populations may interbreed but those well separated geographically may not. Sorting out which are genuinely different species is not easy.
Variation
Most populations of organisms contain individuals which vary slightly from one to another, those with superior characteristics are more likely to survive.
Over-production
Most organisms produce more young than will survive to adulthood ensuring some will survive.
Struggle for existence
Populations do not generally increase rapidly in size there must therefore be considerable competition for survival between the organisms.
Survival
Those with advantageous characteristics are more likely to survive.
Advantageous characteristics
Better adapted organisms are more likely to reproduce successfully passing on the advantageous characteristics to their offspring.
Gradual change
Over a period of time the proportion of individuals with the advantageous characteristics in the population will increase compared with the proportion of individuals with poorly adapted characteristics, and the poorly adapted characteristics may eventually be lost.
Genetic variation
Variation caused by inherited genes.
Environmental variation
Variation caused by the environment.
Continuous variation
When a particular characteristic of an individual lies within a range with no distinct category.
Discontinuous variation
When a particular characteristic of the species fits into a few particular and specific categories with no range of variation.
Mutation
Mutations that are inherited may change the characteristics of the species (genetic variation).
Reproduction
The ‘controlled randomness’ of the possible gene combinations of the offspring inherited from their parents ensures that no offspring can be identical to either parent (genetic variation).
Speciation (Higher)
The development of a new species and can happen when populations of the same original species becomes so different (genetically) that they can no longer interbreed to give fertile offspring.
Geographic isolation (Higher)
Two populations of a species become separated, e.g. geographically.
Charles Darwin
Invented the theory of evolution by natural selection.
Natural selection
The driving force for evolution- the best adapted to survive are able to pass on their advantageous characteristics.
Scientific journals
enable new findings to be communicated to other scientists working in the same areas of science, so ideas and knowledge are widely spread AND other scientists can check whether the research is valid.
Peer review process
a sort of refereeing system, research papers are read and checked by people competent to understand the contents of research papers (their peers) - this ensures standards are high in terms of ‘good scientific practice’.
Scientific conferences
Enable scientists to meet and present and discuss their findings, compare their work, listen to new ideas, get ideas to take back to their own research project. Its also a forum for other scientists to hear about research which isn’t necessarily exactly their own specialist field, but broadens their own knowledge of related fields of science.
Nucleus
The control centre of the cell, containing 23 pairs of chromosomes, on which genes are located.
Chromosomes
Carry the genes which control the development and subsequent characteristics of an organism.
Gene
A gene is a shorter section of the huge DNA coiled up molecules that make up chromosomes- one gene codes for one characteristic.
Genotype
A ‘bit of genetic code’ pairs of or individual alleles e.g. XX, XY, X, Y.
Phenotype
The result of ‘gene expression’ - the nature of the characteristic you see e.g. tall, blue eyes, male etc.
Dominant
If two alleles for a characteristic are different (heterozygous) then only one of the alleles can determine the nature of the characteristic - know as the dominant allele (usually shown as a capital/upper case letter) eg a gene for height might be H, so HH or Hh genotypes will give a tall organism. A dominant allele will override a recessive allele.
Recessive
If an allele is not dominant, it is described as recessive (small/lower case letter), and, in order for the recessive allele to be expressed in the phenotype observed, you must have a double recessive allele eg homozygous genotype hh will give rise to phenotype short.
Homozygous
If a pair alleles for a characteristic are the same on a gene eg genotype XX (phenotype female).
Heterozygous
If a pair of alleles for a characteristic are different on a gene eg genotype XY (phenotype female).
Sickle cell disease
Sickle cell anaemia is a genetic (inherited) blood disorder in which red blood cells (the carriers of oxygen around the body), develop abnormally. Instead of being round and flexible, the sickle red blood cells become shaped like a crescent (hence the name ‘sickle’). These abnormal red blood cells can then clog sections of blood vessels (especially the narrow capillaries) leading to pain. These painful effects can last from a few minutes to several months. The abnormal blood cells have a shorter life-span and are not replaced as quickly as normal healthy red blood cells leading to a shortage of red blood cells, called anaemia. Symptoms of sickle cell anaemia include tiredness, painful joints and muscles and breathlessness, especially after exercise i.e. any extra physical exertion.
Cystic fibrosis
Cystic fibrosis is a genetic disorder disease passed down through families. Cystic fibrosis causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body and is one of the most common chronic lung diseases in children and young adults. Sadly, it is a life-threatening disorder caused by a defective gene which causes the body to produce abnormally thick and sticky fluid, called mucus. The thick mucus builds up in the breathing passages of the lungs (causing lung infections) and in the pancreas, the organ that helps to break down and absorb food (causing digestion problems).
