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B6: Quiz 6 – Answers
B6: Quiz 6 – Answers
1)
a)
i) Recessive allele
ii) Homozygous recessive or ff
b)
i) A carrier is an individual that carries the recessive gene for cystic fibrosis, but they do not have cystic fibrosis (because they have the dominant allele)
ii) They are heterozygous or Ff
c)
i)
a)
i) Recessive allele
ii) Homozygous recessive or ff
b)
i) A carrier is an individual that carries the recessive gene for cystic fibrosis, but they do not have cystic fibrosis (because they have the dominant allele)
ii) They are heterozygous or Ff
c)
i)
ii) 1 : 3
iii) 2 carriers
d) 0% (the Punnett square is shown below)
iii) 2 carriers
d) 0% (the Punnett square is shown below)
2)
a)
i) The offspring are born with extra digits, which are extra fingers or toes
ii) Dominant allele
iii) Homozygous dominant (DD) or heterozygous (Dd)
iv) Homozygous recessive (dd)
b)
i)
2)
a)
i) The offspring are born with extra digits, which are extra fingers or toes
ii) Dominant allele
iii) Homozygous dominant (DD) or heterozygous (Dd)
iv) Homozygous recessive (dd)
b)
i)
ii) 1 : 1
c) 100% (the Punnett square is shown below)
c) 100% (the Punnett square is shown below)
3)
a) The screening of embryos involves taking a few cells from the embryo and analysing the genetic information to see if the genetic information contains any genes for genetic disorders. We are able to screen embryos from IVF (fertilisation in a lab) and from embryos inside the womb of an individual. If any genetic disorders are found, couples can make the decision to terminate the pregnancy/ not use that embryo for IVF
b) Any 2 from:
- Genetic conditions reduce the quality of life for individuals, so by screening embryos, we can prevent suffering
- The treating of genetic conditions is extremely expensive for individuals and the government (very high healthcare costs)
- There are laws that prevent the screening of embryos from going too far – you cannot currently see the hair colour, eye colour etc. of the offspring
- The screening of embryos implies that some genetic conditions are undesirable, which could create prejudice
- Some individuals may want to take the screening process too far and know all of the genetic information about the embryo (eye colour, hair colour etc).
- Screening is an expensive process
Questions
1) This question is all about cystic fibrosis.
a)
i) Is cystic fibrosis caused by a dominant or recessive allele?
ii) What is the only genotype for having cystic fibrosis?
b)
i) Give a definition for being a carrier of cystic fibrosis.
ii) What is the genotype for a carrier of cystic fibrosis?
c) Two carriers for cystic fibrosis have a child.
i) Complete the Punnet square below to show the possible genetic outcomes for the offspring.
1) This question is all about cystic fibrosis.
a)
i) Is cystic fibrosis caused by a dominant or recessive allele?
ii) What is the only genotype for having cystic fibrosis?
b)
i) Give a definition for being a carrier of cystic fibrosis.
ii) What is the genotype for a carrier of cystic fibrosis?
c) Two carriers for cystic fibrosis have a child.
i) Complete the Punnet square below to show the possible genetic outcomes for the offspring.
ii) Give the ratio of the offspring that have cystic fibrosis to the offspring that do not have cystic fibrosis.
ii) How many of the offspring are carriers?
d) A homozygous dominant individual and a carrier of cystic fibrosis have a child. Use a Punnett square to work out the percentage chance that the offspring will have cystic fibrosis.
2)
a)
i) What is polydactyly?
ii) Is it caused by a dominant or recessive allele?
iii) What are the two genotypes for individuals that have polydactyly?
iv) What is the only genotype for individuals that do not have polydactyly?
b) A heterozygous individual has a child with an individual that does not have polydactyly.
i) Draw the Punnett square to show the possible genetic outcomes for the offspring.
ii) How many of the offspring are carriers?
d) A homozygous dominant individual and a carrier of cystic fibrosis have a child. Use a Punnett square to work out the percentage chance that the offspring will have cystic fibrosis.
2)
a)
i) What is polydactyly?
ii) Is it caused by a dominant or recessive allele?
iii) What are the two genotypes for individuals that have polydactyly?
iv) What is the only genotype for individuals that do not have polydactyly?
b) A heterozygous individual has a child with an individual that does not have polydactyly.
i) Draw the Punnett square to show the possible genetic outcomes for the offspring.
ii) Give the ratio of the number of individuals that have polydactyly to the number of individuals that do not have polydactyly.
c) A homozygous recessive individual has a child with a homozygous dominant individual. What percentage of the offspring will have polydactyly?
3) We can screen embryos for genetic disorders.
a) Briefly explain the process for screening embryos for genetic disorders.
b) Give 2 positives for screening embryos for genetic disorders.
c) Give 2 negatives for screening embryos for genetic disorders.
c) A homozygous recessive individual has a child with a homozygous dominant individual. What percentage of the offspring will have polydactyly?
3) We can screen embryos for genetic disorders.
a) Briefly explain the process for screening embryos for genetic disorders.
b) Give 2 positives for screening embryos for genetic disorders.
c) Give 2 negatives for screening embryos for genetic disorders.