AQA GCSE BIOLOGY PAPER 2
QUESTIONS AND CORRECT
ANSWERS
Why can't you have carriers of Polydactyly? ANSW✅✅It is caused by a dominant allele. If you get
one copy of the allele the phenotype will be expressed.
What is the chance of someone not being born with Polydactyly if both parent are heterozygous (Dd)
for the disease. ANSW✅✅25%
How can genetic disorders be detected? ANSW✅✅EMBRYONIC SCREENING
IVF -before implantation-cell can be removed from embryo to analyse genes.
Embryos with defective alleles/genes destroyed.
Also possible to collect and examine DNA from embryo in womb, to test for genetic disorders-
abortion is an option following a positive result.
Embryonic screening 3 pros/3 cons ANSW✅✅Pros
1-helps to stop suffering
2-There are laws to stop it going too far-parents can't select sex of baby.
3-Treatment for genetic disorders costs NHS/tax payers money
Cons
1-implies people with genetic disorders are undesirable, leads to prejudice.
2-Screening is Expensive.
3-Could lead to designer babies e.g. parents want a blonde eyed, blonde haired boy.
What is Variation ? ANSW✅✅inherited differences in Organisms caused by genetics or
environmental factors
How can genes and environmental factors affect variation ? ANSW✅✅Genes-differences in the
genotype
,Environment-e.g.plant-growth controlled by food/light/water etc
What are mutations ? ANSW✅✅Changes to the sequence of bases in DNA. Mutations include
substitutions, deletions and additions.
How do mutations occur? ANSW✅✅Randomly. Increased by exposure to certain substances e.g.
carcinogens and radiation.
Explain why the function of a protein might be affected by a mutation. ANSW✅✅Mutations in the
base sequence could affect the amino acid sequence. This will change the shape of the protein. E.g.
with enzymes the active site might change shape so that the substrate cannot bind.
Give an example of where genetic variants(mutations) determine phenotype ANSW✅✅Cystic
fibrosis caused by a mutation that affects phenotype
GENE codes for a protein that controls movement of salt and water out of cells
The protein produced by the mutated gene doesn't work properly = excess mucus production in
LUNGS & DIGESTIVE SYSTEM-hard to breath & digest
What is the theory of Evolution? ANSW✅✅All of today's species have evolved from simple life
forms that first started to develop over 3 billion years ago
What theory did Charles Darwin come up with? ANSW✅✅Evolution by Natural selection
Variation in species phenotype caused by mutations. Organisms with the most suitable
characteristics/better adapted for the environment would be more successful competitors and be
more likely to survive.
They are more likely to reproduce,passing on the genes for their beneficial characteristics to
offspring. Overtime the beneficial gene increases in the population.
Explain why Darwin's theory was considered controversial when it was first proposed. ANSW✅✅-
Against religious beliefs about how life on Earth developed
-Darwin couldn't explain how these characteristics appeared or how they were passed on.
What 3 things developed/supported Darwin's Theory of Evolution? ANSW✅✅-Discovery of
genetics (Mendel/Watson and Crick)
,-Looking at fossils-changes in organism over time
-Antibiotic resistant bacteria-supports evolution by natural selection
How did the discovery of genetics support Darwin's theory? ANSW✅✅It explained WHY NEW
characteristics appeared or how organisms passed on their beneficial adaptations.
Name another scientist who had a theory about evolution. ANSW✅✅Jean Baptiste Lamarck
Describe Jean Baptiste Lamarck's theory. ANSW✅✅Theory of Acquired characteristics. E.g. if a
giraffe stretched it's neck to reach tall branches over time the neck would get longer.
Describe speciation. ANSW✅✅Speciation-over time, a phenotype of organisms will change so
much due to NATURAL SELECTION that a new species is formed.
When does speciation happen? ANSW✅✅When POPULATIONS of the SAME SPECIES change
enough to become re productively isolated.
This means that they can't inbreed to produce fertile offspring.
What is extinction +4 reasons ANSW✅✅No individuals of a species remain
-Change in environment
-New predator kills them
-Disease
-can't compete with new species for food
What is selective breeding? + process ANSW✅✅Humans artificially select which organisms to
breed so that the GENES for particular characteristics remain in the population
1)select stock with DESIRED CHARACTERISTICS
2)breed them
3)breed best of offspring
4)continue cycle so DESIRABLE TRAIT gets stronger and stronger, until eventually, all offspring will
have this characteristic
, Give some examples of selective breeding ANSW✅✅Agricultural animals to produce more
meat/milk
Crops-disease resistance
Good, friendly dogs
Decorative plants with big, unusual flowers
What is the main issue of selective breeding? ANSW✅✅Reduction in the gene pool-the number of
different alleles in a population
What is inbreeding? + cons ANSW✅✅Where the farmer only breeds from the 'best' of
animals/plants
- more chance of the organisms inheriting harmful GENETIC DISORDERS when the gene pool is
limited
-lack of variation in population=if one dies of a disease, the rest are likely to die too
What is genetic engineering ? ANSW✅✅The transfer of a gene for a desirable characteristic from
one organism's genome into the other's, so that it also has that desired characteristic.
Process of genetic engineering ANSW✅✅1) useful gene cut from one organism's genome using
ENZYMES and inserted into a VECTOR.
2)Vector(virus/bacterial plasmid) inserts useful gene into CELL of organism
Give 3 examples of where genetic engineering has been used ANSW✅✅1)GM crops have
modified genes to improve SIZE/QUALITY of fruit , and make them RESISTANT to herbicides,
pesticides or disease
2)Sheep-PRODUCE DRUGS IN MILK to treat human disease
3) Bacteria have been genetically modified to produce HUMAN INSULIN which can be used to treat
DIABETES.
2 pros & 2 cons of GM crops ANSW✅✅+increased yield=more food
+already being grown, not problematic
-worries on human health/safety/allergies
-long term effects-unplanned problems that could could pass on to future generations
QUESTIONS AND CORRECT
ANSWERS
Why can't you have carriers of Polydactyly? ANSW✅✅It is caused by a dominant allele. If you get
one copy of the allele the phenotype will be expressed.
What is the chance of someone not being born with Polydactyly if both parent are heterozygous (Dd)
for the disease. ANSW✅✅25%
How can genetic disorders be detected? ANSW✅✅EMBRYONIC SCREENING
IVF -before implantation-cell can be removed from embryo to analyse genes.
Embryos with defective alleles/genes destroyed.
Also possible to collect and examine DNA from embryo in womb, to test for genetic disorders-
abortion is an option following a positive result.
Embryonic screening 3 pros/3 cons ANSW✅✅Pros
1-helps to stop suffering
2-There are laws to stop it going too far-parents can't select sex of baby.
3-Treatment for genetic disorders costs NHS/tax payers money
Cons
1-implies people with genetic disorders are undesirable, leads to prejudice.
2-Screening is Expensive.
3-Could lead to designer babies e.g. parents want a blonde eyed, blonde haired boy.
What is Variation ? ANSW✅✅inherited differences in Organisms caused by genetics or
environmental factors
How can genes and environmental factors affect variation ? ANSW✅✅Genes-differences in the
genotype
,Environment-e.g.plant-growth controlled by food/light/water etc
What are mutations ? ANSW✅✅Changes to the sequence of bases in DNA. Mutations include
substitutions, deletions and additions.
How do mutations occur? ANSW✅✅Randomly. Increased by exposure to certain substances e.g.
carcinogens and radiation.
Explain why the function of a protein might be affected by a mutation. ANSW✅✅Mutations in the
base sequence could affect the amino acid sequence. This will change the shape of the protein. E.g.
with enzymes the active site might change shape so that the substrate cannot bind.
Give an example of where genetic variants(mutations) determine phenotype ANSW✅✅Cystic
fibrosis caused by a mutation that affects phenotype
GENE codes for a protein that controls movement of salt and water out of cells
The protein produced by the mutated gene doesn't work properly = excess mucus production in
LUNGS & DIGESTIVE SYSTEM-hard to breath & digest
What is the theory of Evolution? ANSW✅✅All of today's species have evolved from simple life
forms that first started to develop over 3 billion years ago
What theory did Charles Darwin come up with? ANSW✅✅Evolution by Natural selection
Variation in species phenotype caused by mutations. Organisms with the most suitable
characteristics/better adapted for the environment would be more successful competitors and be
more likely to survive.
They are more likely to reproduce,passing on the genes for their beneficial characteristics to
offspring. Overtime the beneficial gene increases in the population.
Explain why Darwin's theory was considered controversial when it was first proposed. ANSW✅✅-
Against religious beliefs about how life on Earth developed
-Darwin couldn't explain how these characteristics appeared or how they were passed on.
What 3 things developed/supported Darwin's Theory of Evolution? ANSW✅✅-Discovery of
genetics (Mendel/Watson and Crick)
,-Looking at fossils-changes in organism over time
-Antibiotic resistant bacteria-supports evolution by natural selection
How did the discovery of genetics support Darwin's theory? ANSW✅✅It explained WHY NEW
characteristics appeared or how organisms passed on their beneficial adaptations.
Name another scientist who had a theory about evolution. ANSW✅✅Jean Baptiste Lamarck
Describe Jean Baptiste Lamarck's theory. ANSW✅✅Theory of Acquired characteristics. E.g. if a
giraffe stretched it's neck to reach tall branches over time the neck would get longer.
Describe speciation. ANSW✅✅Speciation-over time, a phenotype of organisms will change so
much due to NATURAL SELECTION that a new species is formed.
When does speciation happen? ANSW✅✅When POPULATIONS of the SAME SPECIES change
enough to become re productively isolated.
This means that they can't inbreed to produce fertile offspring.
What is extinction +4 reasons ANSW✅✅No individuals of a species remain
-Change in environment
-New predator kills them
-Disease
-can't compete with new species for food
What is selective breeding? + process ANSW✅✅Humans artificially select which organisms to
breed so that the GENES for particular characteristics remain in the population
1)select stock with DESIRED CHARACTERISTICS
2)breed them
3)breed best of offspring
4)continue cycle so DESIRABLE TRAIT gets stronger and stronger, until eventually, all offspring will
have this characteristic
, Give some examples of selective breeding ANSW✅✅Agricultural animals to produce more
meat/milk
Crops-disease resistance
Good, friendly dogs
Decorative plants with big, unusual flowers
What is the main issue of selective breeding? ANSW✅✅Reduction in the gene pool-the number of
different alleles in a population
What is inbreeding? + cons ANSW✅✅Where the farmer only breeds from the 'best' of
animals/plants
- more chance of the organisms inheriting harmful GENETIC DISORDERS when the gene pool is
limited
-lack of variation in population=if one dies of a disease, the rest are likely to die too
What is genetic engineering ? ANSW✅✅The transfer of a gene for a desirable characteristic from
one organism's genome into the other's, so that it also has that desired characteristic.
Process of genetic engineering ANSW✅✅1) useful gene cut from one organism's genome using
ENZYMES and inserted into a VECTOR.
2)Vector(virus/bacterial plasmid) inserts useful gene into CELL of organism
Give 3 examples of where genetic engineering has been used ANSW✅✅1)GM crops have
modified genes to improve SIZE/QUALITY of fruit , and make them RESISTANT to herbicides,
pesticides or disease
2)Sheep-PRODUCE DRUGS IN MILK to treat human disease
3) Bacteria have been genetically modified to produce HUMAN INSULIN which can be used to treat
DIABETES.
2 pros & 2 cons of GM crops ANSW✅✅+increased yield=more food
+already being grown, not problematic
-worries on human health/safety/allergies
-long term effects-unplanned problems that could could pass on to future generations
