year 10 EOY exam- science

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120 Terms
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deoxyribonucleic acid
self replicating molecule present in all living organisms. Main constituent of chromosomes
Threadlike structure of nucleic acids- carry genetic information in the form of genes
Having the same/similar structural features and patterns of genes
length of dna that carries the genetic code for a particular characteristic
nitrogen base
cytosine, adenine, guanine and thymine
a genetically determined characteristic
particular allele of an organism
what an organism looks like as a consequence of the interaction of its genotype and the environment
two alleles that are the same for a particular trait
two alleles that are different for a particular trait
dominant allele
an allele that produces the same phenotype whether its paired allele is identical or different
recessive allele
an allele that produces its characteristic phenotype only when its paired allele is identical
23 sets of chromosomes, an individual's complete set of chromosomes
alteration to the nucleic acid sequence of a genome of an organism
asexual reproduction
reproduction without gametes, offspring are usually genetically identical
genetic variation
genetic differences within organisms of a population
artificial selection
choosing to breed different animals or fruits to achieve a desired outcome
natural selection
breeding happens naturally
complementary base pairing
bases in DNA can only pair with their complementary base- AT and GC
all chromosomes in a cell other than sex chromosomes
one of two identical strands into which a chromosome splits during mitosis
cell division in which the nucleus divides into nuclei containing the same number of chromosomes
cell division that produces reproductive cells in sexually reproducing organisms
a mature sexual reproductive cell having a single set of unpaired chromosomes
homologous chromosome
homologous chromosomes have the centromere in the same position and genes for characteristic
alkali metals
form 1+ ions, extremely reactive, react violently with water
alkali earth metals
act in a less reactive way to alkali metals, form 2+ ions
group 14
includes metals, non metals and metalloids, many elements exist in allotropes
form -1 ions, found in salts rather than pure forms, get bigger and less reactive down the group, form molecules of 2 atoms
noble gases
stable and only react under extreme circumstances, colourless and occur naturally in the atmosphere, get denser down the group
exothermic reaction
a chemical reaction that releases energy in the form of light or heat
endothermic reaction
a chemical reaction that absorbs heat, feels cold
any chemical reaction in which a substance burns in oxygen gas to produce light and heat
substances that are made of only hydrogen and carbon atoms eg. methane
incomplete combustion
combustion is incomplete when there is limited oxygen supply and produces carbon monoxide
a state of deterioration in metals caused by oxidation or chemical action
decomposition reaction
decomposition reactions are when a single reactant breaks down to form several products, general equation XY→ X + Y
thermal decomposition
when a substance decomposes when heat is applied
combination reaction
when two or more reactants combine into one product
precipitation reaction
when two soluble reactants combine to form an insoluble product known as the precipitate
ionic compound
contain ions and are held together by the attractive forces among the oppositely charged ions, are often metals and non metals
neutralisation reaction
reaction between an acid and a base which produces a salt and water
any substance which produces H+ ions when dissolved in water and turns litmus paper red
any substance which produces OH- ions when dissolved in water and turns litmus paper blue
ionic compounds that are produced with a chemical reaction with an acid
acid and metal reaction
acid + metal -> salt + hydrogen
acid and carbonate reaction
acid + carbonate -> carbonate salt + water + carbon dioxide
effect of temperature on a reaction
increases the speed of particles in liquid or gases so they collide more frequently and increases the energy in particles so that they collide harder and bonds are more likely to break
effect of concentration on a reaction
increases the rate of reaction- particles are more likely to collide when there are more of them
effect of agitation on a reaction
stirring- ensures that the reactants are kept in contact and removes build up of products around the reactants
effect of surface area on a reaction
possibility for reactants to react with it from multiple angles, which increases the rate of reaction
effect of catalyst on a reaction
reduce the amount of energy required to convert the reactants into the products and make it easier for reactants to collide
change in proportion of a particular genotype of a species over many generations due to environmental selection of a particular phenotype, forming a new species
homologous structure
characteristics that have the same basic structure eg. cat paw and lion paw, and have the similar ancestors
analogous structure
structures that look similar on genetically different organisms even though they do not share an ancestor
natural selection
the process where an environmental factor acts on a population and results in some organisms having more offspring than others
selective agent
the environmental factor that acts on a population
biotic factor
a factor relating to living things eg disease or lack of food
a factor unrelated to living things eg drought
straight line distance between two points
average speed
the overall speed of an object excluding changes in speed over a journey
instantaneous speed
the speed of an object at a particular instant
air resistance
the friction between air and an object
gene splicing
the process used to add a gene into or remove genes from DNA
gene therapy
replacing a defective gene with a normal gene
the genetic information carried by a haploid set of chromosomes
a ring of DNA found in bacteria
recombinant dna technology
technology that allows dna to be recombined with other genes
adult stem cells
cells that can make certain types of body cells
embryonic stem cells
cells found in the embryo that are pluripotent
cells that are capable of becoming any type of cell in the human body
the preserved evidence in rocks or soils of organisms that once existed on earth
how are fossils formed?
when sediment builds up over the remains of an organism so that it does not decompose
original fossil
when a part of the organism is preserved with its chemical composition being the same as when it was living
replacement fossil
when the organism has chemically changed into another mineral
carbon film fossil
occur when the dead body partially decays and leaves a black deposit of carbon but none of the organism actually remains
indirect fossil
not part of the organism but are preserved forms of things such as footprints or fossilised dung
permafrost fossil
organisms that cause decay cannot grow in permafrost
fossil mould
imprint of the outside of the body in rock
amber fossil
when plant sap or gum has turned solid and small creatures get stuck in it
tar fossil
when oil seeps out of the ground onto the surface and organisms get trapped
partly decomposed remains of plants, oxygen and bacteria are not found in the lowest layers of peat
dry air fossil
extremely dry conditions prevent bacteria from causing decay
relative dating
compares the age of one fossil or rock with another to determine which is older
which two facts does relative dating rely on?
sedimentary rocks forming in layers and that fossils are the same age as the rocks they are found in
layer by layer
sediment always settles, therefore the fossils at the bottom layers of sediment are always the oldest
layers of sedimentary rock
index fossils
a fossil that is useful for dating and correlating the strata in which it is found
fluorine analysis
compares the amount of fluorine in different bones found in the same rock
radioactive dating
measurement of the amount of radioactive material that a fossil contains, uses the natural rate of decay of radioactive isotopes to estimate the age
big bang theory
theory that the universe began with a colossal explosion 114 billion years ago and has been expanding since
evidence that supports the big bang theory
cosmic microwave background and red shift
cosmic microwave background
a type of radiation that remains since the explosion millions of years ago and fills the whole universe
red shift
light from stars moving closer is blue, while stars that move further away appears red, shows that the energy from the explosion is spreading stars apart
two organisms which can breed to produce fertile offspring
the process by which one species splits into two or more separate species
three steps of speciation
variation, isolation, selection
evidence for evolution
fossils, distribution, comparative anatomy, dna and protein analysis, embryology
nuclear reaction
a process in which the nucleus of an atom is changed by being split apart or joined with the nucleus of another atom
alpha decay
when the nucleus ejects alpha particles consisting of two protons and two neutrons
alpha particle
a particle made up of two protons and two neutrons
alpha radiation
a form of ionising radiation made up of alpha particles
beta decay
nuclear decay that ejects a beta particle, and converts neutrons into protons
beta particle
a small negatively charged particle that is identical to an electron
electromagnetic radiation
radiation that travels through a vacuum as waves rather than particles
a nuclear reaction in which a large nucleus splits into two smaller nuclei of similar mass number
two smaller nuclei come together to form one larger nucleus
gamma decay
nuclear decay that involves the release of gamma rays
gamma radiation
a form of ionising radiation made up of gamma rays
gamma ray
a high energy electromagnetic wave that is produced when protons and neutrons in a nucleus rearrange
half life
the time it takes for half the nuclei to decay
ionising radiation
any form of radiation that has the ability to remove electrons from atoms and molecules
radiation burns
redness and blistering on the surface of the skin or other organs caused by intense exposure to ionising radiation
radiation sickness
a condition that results from a large dose of ionising radiation, causing significant cell death
an isotope with a nucleus that may undergo a nuclear reaction
stable nuclei
nuclei that will never undergo a nuclear reaction
the change of one chemical element into another
newton's first law
an object at rest will remain that way unless it is acted upon by a force
newton's second law
an object will accelerate in the direction of an unbalanced force acting on it
newton's third law
for every action force there is an equal and opposite reaction force