Unit 2: how is continuity of life maintained?

Chromosomes

The role of chromosomes as structures that pack DNA, their variability in terms of size and the number of genes they carry in different organisms, the distinction between an autosome and a sex chromosome and the nature of a homologous pair of chromosomes as carrying the same gene loci

Presentation of an organisms set of chromosomes as a karyotype that can be used to identify chromosome number abnormalities

Down's, Klinefelter's and Turner's syndromes in humans

Genotypes and phenotypes

The use of symbols in the writing of the genotypes for the alleles present at a particular gene location.

The distinction between a dominant and recessive phenotype.

The relative influences of a genetic material, environmental factors and interactions of DNA with other molecules (epigenetic factors) on phenotypes.

Qualitative treatment of polygenic inheritance as contributing to continuous variation in a population, illustrated by the determination of human skin colour through the genes involved in melanin production or by variation in height.

Genomes, genes and alleles

The distinction between a genome, gene and allele.

The genome as the sum total of an organism's DNA
measured in the number of base pairs contained in a
haploid set of chromosomes.

The role of genomic research since the Human Genome
Project, with reference to the sequencing of the genes of many organisms, comparing relatedness between species, determining gene function and genomic applications for the early detection and diagnosis of human diseases.

Pedigree charts, genetic cross outcomes
and genetic decision-making

Pedigree charts and patterns of inheritance including
autosomal dominant, autosomal recessive, X-linked
and Y-linked traits.

The determination of genotypes and predictions of the
of the outcomes of genetic crosses including monohybrid
crosses, and monohybrid test crosses.

The inheritance of two characteristics as either independent
or linked, and the biological consequences of crossing over linked genes.

The nature and uses of genetic testing for screening of embryos and adults, and its social and ethical implications.

Cell growth and cell differentiation

The types and function of stem cells in human development

The distinction between embryonic and adult stem
cells and their potential use in the development of medical therapies

The consequences of stem cell differentiation in human development

The development of germ layers, types of tissues formed from
germ layers and the distinction between embryo and foetus

The disruption of the regulation of the cell cycle through genetic predisposition or the action of mutagens that gives rise to the uncontrolled cell division

Cancer and abnormal embryonic development

Asexual reproduction

The types of asexual reproduction

Fission, budding, vegetative propagation and spore formation

The biological advantages and disadvantages of asexual reproduction

Emerging issues associated with cloning

Applications in agriculture and horticulture

Che cell cycle

Derivation of all cells from pre-existing cells through completion of the cell cycles

The rapid procession of prokaryotic cells through their cell cycle by binary fission

The key events in the phases (G1, S, G2, M and C) of the eukaryotic cell cycles

Characteristics of the sub-phases of mitosis (prophase, metaphase, anaphase and telophase) and cytokinesis in plants and animal cells

Sexual reproduction

How an offspring from two parents has a unique genetic identity

The key events that result in the production of gametes from somatic cells

The significance of crossing over of chromatids between homologous chromosomes in prophase 1 and the non-dividing of the centromere in metaphase 1

The biological advantage of sexual reproduction, specifically the genetic diversity in offspring

the characteristics of effective science communication: accuracy of biological information; clarity of explanation of biological concepts, ideas and models; contextual clarity with reference to importance and implications of findings; conciseness and coherence; and appropriateness for purpose and audience.

the biological concepts specific to the investigation: definitions of key terms; use of appropriate biological terminology, conventions and representations.

the use of data representations, models and theories in organising and explaining observed phenomena and biological concepts and their limitations.

the nature of evidence and information: distinction between opinion, anecdote and evidence, weak and strong evidence, scientific and non-scientific ideas; and validity, reliability and authority of data including sources of possible errors or bias.

the influence of social, economic, legal and ethical factors relevant to the selected biological issue.