Meiosis & Variation 0.0 / 5 ? BiologyCellular processesA2/A-levelOCR Created by: BioFreakinomicsCreated on: 03-03-16 12:05 Phytogenetic Species Concept Defining a species as a group of similar organisms that have similar morphalogy, phisiology, embryology & behaviour 1 of 39 Biological Species Concept Defining a species as a group of similar organisms that can interbreed & produce fertile offspring 2 of 39 Genetic Shift The change in allele frequency in a population 3 of 39 Selection Pressure The environmental factor that confers greater chances of surviving 4 of 39 Carrying Capacity The maximum population size that can be maintained over a period of time in a particular habitat 5 of 39 Discontinuous Variation Phenotypic differences with clearly distinguisable catergories (qualitative) 6 of 39 Continuous Variation Phenotypic differences with no distinct catergories (quantative) 7 of 39 Population A group of individuals of the same species that can interbreed living in the same place at the same time 8 of 39 Null Hypothesis There is no significant difference between the observed & expected results, any difference is due to chance 9 of 39 Chi Squared A statistical test to see whether there is a significant difference between observed & expected results 10 of 39 Complimentary Epistasis At least 1 dominant allele is required at 2 different loci to result in the expression on 1 phenotype 11 of 39 Dominant Epistais A dominant allele at 12 locus prevents the expression of alleles at a 2nd locus 12 of 39 Recessive Epistasis Homozygous recessive alleles at 1 locus prevent the expression of an allele at another locus 13 of 39 Epistasis The interaction of genes on different loci where one gene masks or supresses the expression of another 14 of 39 Dihybrid Inheritance When 2 characteristics located on different pairs of homologus chromosomes can be inherited together 15 of 39 Codominant A characteristic where both alleles contribute to the phenotype 16 of 39 Recessive Characteristic in which the allele responsible is only expressed in the phenotype if there is no dominat allele present 17 of 39 Dominant Characteristic in which the allele responsible is expressed in the phenotype even in those with heterozygous genotypes 18 of 39 Heterozygous 2 different alleles fo a gene 19 of 39 Homozygous 2 identical alleles for a gene 20 of 39 Phenotype Observable characteristic of an organism 21 of 39 Genotype The alleles present in an individual for a particulart characteristic 22 of 39 Gene A length of DNA that codes for 1 or more polypeptides. some genes code for RNA & regulate other genes 23 of 39 Genetic Variation Variation of genetic information in a gene pool 24 of 39 Mutation Structural change to genetic material either a gene or a chromosome 25 of 39 Zygote A diploid cell resulting from the fusion of 2 haploid gametes 26 of 39 Oocyte A cell in an ovary which may undergo meiotic division to form an ovum 27 of 39 Ovum A mature female reproductive cell of an animal especially 28 of 39 Spermatozoa The mature motile male sex call of an animal, typically having a compact head & 1 or more long flagella for swimming 29 of 39 Centromeres The region of the chromosome to which the spindle fibre is attached during cell division 30 of 39 Haploid Cells A cell that has half the usual number of chromosomes 31 of 39 Chromatin A complex of nucleic acids & proteins, which condenses to form a chromosome during cell division 32 of 39 Gametes Specialised sex cells, in many organisms the gametes are haploid & are produced by meiosis 33 of 39 Allele An alternative version of a gene 34 of 39 Crossing Over Where non-sister chromatids exchange alleles during prophase I of meiosis 35 of 39 Chiasmata The points where non-sister chromatids within a bivalent join 36 of 39 Bivalent Pair of synapsed homlogous chromosomes during prophase I & metaphase I 37 of 39 Meiosis A reduction division in which the resulting daughter cells are haploids that can be used for sexual reproduction 38 of 39 Homologous Chromosomes A pair of chromosomes with the same gene sequence as another 39 of 39
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