this document contains all the definitions you need to know for the grade 12 ieb life science syllabus. this document has the definitions for paper 1 and paper 2.
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Genetics Study of the mechanism of hereditary by which characteristics
are passed from one generation to the next
Genetic variation Different genes
Environmental variation Same genes, appear differently due to the environment
Dominant characteristics Express themselves over other characteristics
Recessive characteristics Cannot express themselves if dominant characteristics are
present
Gene Section on chromosome controlling characteristics
Allele Gene on homologous chromosome that controls same
characteristic (found on same position on chromosome – locus)
Homozygous Same alleles
Heterozygous Different alleles
Genotype Make up of organisms genes (represented by letters)
Phenotype Physical characteristic of organism (physical appearance)
Incomplete dominance Heterozygotes are intermediate (blend of parental dominance)
Co-dominance Both characteristics are expressed equally
Genetic diseases/ inherited disorders Disease occurs in the DNA of the gene
Pedigree diagrams/ family trees Trace the inheritance of particular characteristic of several
generations
Autosomes The numbered chromosomes (not the XX/XY chromosomes)
Gonosome One pair of chromosomes that control gender (XX/XY)
Chromosomal abnormalities Meiotic failures during gamete formation
Polyploid (plants) Two sets of chromosomes in each cell
Triploid 3 sets of chromosomes
Translocation Chromosomes swapped around
Phosphate Small organic molecule containing oxygen and phosphorus
Nitrogenous base Purines (larger) and pyrimidines (smaller)
DNA Deoxyribose nucleic acid (C5H1004)
RNA Ribose nucleic acid (C5H1005)
Semi-conservative replication DNA replication
Gene Section of DNA that contains the coded instructions for making
a particular protein
Codon Three consecutive nucleotides that code for a particular amino
acid
Transcription Copying of DNA onto RNA
Biotechnology Field of study that used living organisms and their metabolic
process to develop pharmaceutical and agricultural products to
improve human life
Plant cutting A piece of leave or stem is placed in water and soil for an
identical plant to be produced
, LIFE SCIENCE DEFINITIONS
Pluripotent Plant cells have the ability to grow and differentiate into adult
plants
Cloning A genetically identical copy of molecule or organism is created
DNA cloning Making copies of genes or entire chromosomes
Polymerase Chain Reaction (PCR) Replicates a piece of DNA many times
Therapeutic cloning Extraction of stem cells from embryo or adult tissue to help
treat leukaemia
Reproductive cloning The production of a plant or animal with the same DNA as each
other
SCNT Somatic Cell Nuclear Transfer
Stem cells Undifferentiated somatic cell
IPSC Induced Pluripotent Stem Cells
Genetic engineering (modification) Transferring of a piece of DNA containing a particular gene
from one organism to another
Restriction enzyme Removes gene from the DNA within the nucleus of an organism
Genome testing Sequencing of all bases on human DNA
CRISPR cas 9 Clustered Regular Interspaced Short Palindromic Repeats
Endocrine glands Secrete hormones and are chemical messengers
Hormone Large organic compound (protein) that is secreted into the
blood and cause a response at the target organ
Receptors Complex molecule on the cell membrane that affects the
functioning of the cell when activated
Pituitary gland Master gland that regulates the functioning of other glands
Growth hormone Regulates the growth of the body (muscles and bones)
Thyroid stimulating hormone (TSH) Stimulates the thyroid to produce thyroxine
Prolactin Stimulates mammary glands to produce milk
Reproductive stimulating hormone Control the function of ovaries and testes
Anti-diuretic hormone (ADH) Controls the reabsorption of water in the kidneys and regulates
blood pressure
Oxytocin Stimulates contractions in the uterus for birth
Adrenaline Prepares the body to cope with stress and trauma
Cortisone Reduces inflammation and controls water balance in the body
Aldosterone Controls the salt balance in kidney and controls the
reabsorption of Na and K in the kidney
Islets of Langerhans Specialised endocrine cells in the pancreas composed of alpha
and beta cells
Testes (endocrine system) Secrete testosterone, control sperm production and male body
characteristics
Ovaries (endocrine system) Secrete progesterone and oestrogen and control ovulation and
female body characteristics
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