MY Science 🧪 Flashcards
what are homozygous alleles?
alleles which are the same
what is the human male sex cell?
sperm
stages of selective breeding?
- two parents with desired characteristic
- breed together
- choose offspring with desired characteristic
- breed together
- repeat over many generations
which type of variation is scar on your arm?
environmental
two disadvantages of selective breeding?
- ‘inbreeding’
- more likely to be susceptible to diseases
forms of each gene we inherit?
two forms called alleles
one from each parent
what does GMO stand for
genetically modified organism
function of cell membrane?
controls what enters and leaves the cell
recessive genetic disorder?
a genetic disorder where the individual has two faulty alleles
one from each parent
when an egg and sperm cell fuse it’s called…
fertilisation
female sex cell?
egg
normal human body amount of chromosomes
46
how is DNA arranged in the nuclei of cells?
strands called chromosomes
what is a gene?
a section of a chromosome that codes for a particular characteristic
what is the function of the nucleus of a cell?
contains the DNA (chromosomes)
what does DNA stand for?
Deoxyribonucleic acid
what is an allele?
a different form of a gene. (eg. gene is eye colour, alleles might be brown, blue or green)
what does heterozygous alleles mean?
two different alleles
what sex chromosomes has a male inherited?
XY
what sex chromosomes has a woman inherited
XX
in a human sex cell how many chromosomes?
23
what are the two types of variation effecting phenotype?
genetic and environmental variation
how is blood type inherited?
genetically
what is a genetic disorder?
caused by a faulty gene or chromosome
what is a dominant genetic disorder?
a genetic disorder where the individual only needs to inherit one faulty allele to get the disorder.
selective breeding?
humans choose parents to breed together because they have desirable characteristics and are likely to produce similar offspring
two advantages of breeding crops by selective breeding?
- different patterns on plants (decoration)
- increased yield
two advantages of breeding animals by selective breeding?
- increased milk/meat yield (profit)
- domesticated animals with gentle nature (pets)
what does genetic engineering involve?
changing the genes of an organism by introducing a gene from another organism to give a desired characteristic
what are the stages of genetic engineering?
1) select desired characteristic (eg. insulin gene)
2) isolate the gene responsible for the characteristic (using enzymes)
3) insert the gene into another organism (eg. bacterium)
4) replicate the organism
2 advantages of genetic engineering?
- enhanced nutrient composition
- improved resistance to pesticides
2 disadvantages of genetic engineering?
- inserted genes may have side effects
- possible harm when the GM crops are eaten by humans/ other animals
what is cloning?
making a genetically identical copy of an individual
what are the 2 types of clone that can be produced?
natural cloning and artificial cloning
give an example of natural cloning in animals
identical twins
2 advantages of cloning
- can produce offspring with desirable characteristics
- study of clones could help treat/cure certain diseases
How is average rate of reaction calculated?
Quantity of reactant used / time
or
Quantity of reactant formed / time
What are 4 ways to speed up a reaction?
- Surface area
- catalyst
- greater concentration
- temperature
What causes a reaction?
Molecules with enough energy and hitting the other reactive molecule sucessfully colliding.
What causes a reaction to not happen?
- Reactants move too slowly
- reactants not facing the right way
What is the activation energy?
The amount of energy needed for a sucessful collision to occur.
How to calculate rate of reaction at a certain point?
Use a tangent with equal distance away from the curve on either side and divide height by base
How to find the rate of reaction on a graph?
1) Find the time taken until the reaction was complete
2) find the amount of product lost
3) divide the amount of product lost by the time
Why is a reaction fastest at the start?
more reactant particles are present at the start so there are more successful collisions
Why does a reaction stop?
One of the reactants has fully reacted or doesn’t have the energy required to reach the activation energy.
Why does increasing the temperature also increase the rate of reaction?
- particles have more kinetic energy therefore more reach the activation energy
- they collide more often due to moving faster
what is collision theory?
the theory that chemical reactions only happen when reactant particles collide with sufficient energy.
why does surface area affect rate of reaction?
more particles are exposed with the smaller pieces of solid reactants, therefore more frequent collisions
what is an independant variable?
a variable that you change to get different results
what is a dependant variable?
the variable you are measuring
what is a control variable
the variable you keep the same
how does a catalyst work?
provides an alternative reaction pathway with a lower activation energy
what does a higher concentration do to rate of reaction?
more frequent collisions, because there are more reactant particles per dm3 than a lower concentration
what is a catalyst?
a substance that can increase the rate of a reaction without being used up itself.
what is the structure of dna?
double helix
what is the name of the cell formed when a sperm fuses with an egg cell?
zygote
where are sperm cells produced?
the testes
where are egg cells produced?
the ovaries
what is the difference between asexual and sexual reproduction?
in asexual there is an genetically identical copy of a single parent. in sexual reproduction both parents contribute genetic information
use a genetic diagram to show how two of their children came to have _______
1) draw the diagram
2) explain the diagram
3) show genotype, phenotype, chance of having ____, chance of not having ________
what is genotype?
the pairs of alleles possible *Dd, dd, Dd, dd
what is a phenotype?
the result of the characteristic shown *Brown, Blue, Brown, Blue
which apparatus is used to measure liquids?
measuring cylinder
what does cotton wool do for an experiment?
stops water getting out
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