Define Diffusion
The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient.
Define Osmosis
The net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane.
Define Active Transport
The movement of particles, using energy, from a region of lower concentration to a region of higher concentration, against a concentration gradient, through a partially permeable membrane.
Define Enzyme
A biological catalyst made of protein, that speeds up the rate of chemical reactions, and remain chemically unchanged at the end of the reaction.
Define Aerobic Respiration
The process where food substances are broken down into carbon dioxide and water, in the presence of oxygen, releasing a large amount of energy.
Define Anaerobic Respiration
The process where food substances are broken down into lactic acid, in the absence of oxygen, releasing a small amount of energy.
Define Oxygen Debt
The amount of oxygen needed to remove lactic acid from the body.
Define Excretion
The removal of metabolic waste products, toxic substances and substances in excess from the body.
Define Homeostasis
The maintenance of a constant internal environment via negative feedback.
Define Hormone
A chemical substance produced in minute quantities by an endocrine gland. It is transported in the bloodstream to one or more target organs where it exerts its effects.
Define Vaccine
Contains an agent resembling a pathogen, and prevent infectious diseases by stimulating white blood cells to quickly produce antibodies when the pathogen invades.
Define Transpiration
The loss of water vapour from the aerial parts of a plant, mainly through the stomata in its leaves.
Define Translocation
The transport of manufactured food substances, such as sugars and amino acids in plants
Define Gene
A unit of inheritance that determines a specific trait in an organism. It is a sequence of DNA nucleotides that codes for specific polypeptide, and has a particular gene locus.
Define Asexual Reproduction
The process that produces genetically identical offspring from one parent, without the fusion of nuclei of male and female gametes.
Define Sexual Reproduction
The process that involves the fusion of nuclei of male and female gametes to form a diploid zygote, producing genetically different offspring.
Define Mitosis
The type of cell division which produces two genetically identical daughter cells which have the same number of chromosomes as the parent cell.
Define Diploid
Having two complete sets of chromosomes, one from each parent.
Define Meiosis
The type of cell division which produces four genetically different daughter cells in which chromosome number is half that of the parent cell, due to the separation of homologous chromosomes.
Define Haploid
Having only one complete set of chromosomes.
Define Allele
One of the alternative forms of the same gene, that occupies the same gene locus on a pair of homologous chromosomes.
Define Codominance
Two different alleles for a particular trait are both expressed in a heterozygote, and the resulting phenotype is an intermediate between the two alleles.
Define Multiple Alleles
A gene that exists in more than two different forms
Define Mutation
The change in the sequence of a gene or in the chromosome number
