Science Half Yearly Study Year 10

Chapters 15, 16 and 11

reactant

the substances present at the start of a reaction and that undergo change during a chemical reaction

product

the substances formed by a chemical reaction

synthesis

the combination of two or more substances to form one compound

decomposition

a reaction where a compound breaks down into two or more elements

alkali

a base that dissolves in water

alkaline solution

a solution that contains a base

indicator

a substance that changes colour in the presence of an acid or a base

litmus paper

a paper containing an indicator that turns red when exposed to an acid and blue when exposed to a base

pH scale

a scale that represents the acidity or basicity of a solution. PH < 7 indicates an acid, PH > 7 indicates a base, PH = 7 indicates a neutral solution

neutral

pH 7 where it is neither a base or an acid

salts

formed in a reaction between an acid and a base

neutralisation reaction

a reaction between an acid and a base that produces water and a salt

corrosion

the gradual destruction of materials by a chemical reaction within their environment

metal oxide

a molecule containing a metal and oxygen

galvanising

to coat iron or steel in a layer of zinc for protection

fuel

a substance that undergoes a chemical reaction to produce a large amount of energy at a fast but controllable rate

combustion

an exothermic reaction between a fuel and oxygen that produces heat, carbon dioxide and water

hydrocarbon

a compound of hydrogen and carbon

precipitate

an insoluble compound formed in a precipitation reaction

precipitation reaction

a reaction where two soluble ionic solutions mix to form an insoluble substance as a product

endothermic reaction

a chemical reaction that absorbs energy in the form of heat

exothermic reaction

a chemical reaction that releases energy in the form of heat or light

chemical bond

an attraction between atoms or ions that allows for the formation of chemical compounds

reaction rate

how fast or slow a reaction proceeds

collision theory

a theory that states that particles involved in a chemical reaction must collide in order to react

catalyst

a substance that increases the rate of a reaction but is not used up in the reaction

enzyme

a catalyst that is used in living

biodegradable

an object or a substance that can be broken down by bacteria, fungi and other living organisms

polymers

giant molecules made from the joining of many smaller molecules

gamete

a sex cell containing half the number of chromosomes of other body cells

sperm

the male gamete of animals

ovum

the female gamete of animals and some plants

haploid

a nucleus that contains one complete set of chromosomes; usually found in a gamete

diploid

a nucleus that contains two complete sets of chromosomes

meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in production of gametes

deoxyribonucleic acid (DNA)

a molecule that contains all the instructions for every job performed by the cell

nucleotide

the building block of DNA consisting of deoxyribose sugar, phosphate and nitrogen base

adenine

a nucleotide of DNA or RNA that is complementary to thymine in DNA and uracil in RNA

guanine

a nucleotide of DNA or RNA that is complementary to cytosine

cytosine

a nucleotide of DNA or RNA that is complementary to guanine

thymine

a nucleotide of DNA that is complementary to adenine

complementary base

a nucleotide base that pairs with its partner nucleotide on the alternative DNA strand. Adenine pairs with thymine, and cytosine pairs with guanine

ribonucleic acid (RNA)

a complementary copy of DNA that is able to carry the genetic message from the nucleus to the cytoplasm

bivalent chromosome

a chromosome that has duplicated, consisting of two sister chromatids joined at a centromere

chromatid

one half of a duplicated chromosome

karyotype

the arrangement of a complete set of chromosomes in pairs of decreasing size

gene

a specific sequence of DNA that codes for a particular trait, usually a protein

genetic code

the sequence of nucleotides found in DNA that is inherited from parents

transcription

the formation of complementary RNA from DNA

codon

sequence of 3 nitrogen bases in RNA

translation

the formation of a protein from RNA that occurs on a ribosome

principal of segregation

pairs of gene variants are separated into reproductive cells

principal of independent assortment

the inheritance of one set of factors from one parent is separate from the inheritance of other factors

mutagen

a chemical or physical agent that causes a change in DNA

genetic mutation

a permanent change in the sequence of nucleotides in DNA

allele

a version of a gene; each person inherits one allele from each parent

homozygous

having two identical alleles for a particular trait

heterozygous

having two different alleles for a particular trait; a carrier for the recessive trait

dominant trait

a characteristic that needs only one copy of an allele to appear in the physical appearance of an organism

recessive trait

a characteristic that results from the inheritance of two identical alleles

carrier

a person who is heterozygous and therefore has one recessive allele that is not expressed in their phenotype

genotype

the combination of alleles for a particular trait

phenotype

the physical characteristics that result from an interaction between the genotype and the environment

Punnett square

a diagram that is used to predict the outcome of breeding organisms

autosome

a chromosome that does not determine the sex of an organism

sex chromosome

a chromosome that determines the sex of an organism

pedigree

a diagram showing the inheritance pattern of a particular trait