3.4 inheritance

Question 1

describe the methodology and conclusions drawn from mendels pea plant experiment

Answer 1

method:

mendel crossed pure breeding pea plants (P generation), then crossed large numbers of the offspring (F1)

he did this for a variety of different characteristics (flower color, plant height)

conclusions:

mendel concluded that organisms have discrete factors that control inheritance of traits (genes)

there are different versions of these factors (alleles) and each parent passes on one copy to the offspring

only one version gets expressed (dominance/ recessiveness)

Question 2

explain how sexual reproduction results in diploid zygotes with two alleles for each characteristic

Answer 2

parents each pass on one copy of every chromosomes to offspring via haploid gametes

the resulting zygote is diploid and therefore possesses two copies of every gene

these alternative copies of a gene are called alleles

Question 3

differentiate between homozygous, heterozygous and hemizygous

Answer 3

homozygous: alleles that are the same for a given characteristic

heterozygous: alleles are different for a given characteristic

homozygous: there is only one allele (occurs in males for sex chromosome traits)

Question 4

distinguish between complete dominance and co dominance

Answer 4

complete dominance- one allele (dominant) masks expression of other allele (recessive) in heterozygotes

codominance- both alleles are expressed within a heterozygous phenotype

Question 5

possible genotypes for the following blood groups

Answer 5

phenotype: type A
genotype: I^A I^A and I^A i

phenotype: type B
genotype: I I and I i

phenotype: type AB
genotype: I^A I^B

phenotype: type O
genotype: i i

Question 6

identify which blood group is the universal donor and which is the universal acceptor

Answer 6

O is the universal donor
AB is the universal acceptor

Question 7

define sex linkage and identify two examples of sex linked conditions

Answer 7

sex linkage refers to any gene/trait that is located on the sex chromosomes X or Y

two examples of X linked recessive conditions are hemophilia and red-green color blindness

Question 8

outline why X linked recessive disorders are more common in males

Answer 8

males have only one X chromosome and so cannot be carriers for recessive conditions

Question 9

describe the inheritance and cause of the following genetic diseases

Answer 9

cystic fibrosis:

-autosomal recessive disease
-caused by a mutation of the CFTR gene on chromosome 7
-causes the production of sticky mucus leading to obstructed airways and digestive issues

huntington’s disease:
-autosomal dominant disease
-caused by a mutation to the HTT gene on chromosome 4
-abnormal production of the Huntington protein leads to neuro degeneration and dementia

Question 10

compare the health consequences associated with the Hiroshima bombing and chernobyl meltdown

Answer 10

chernobyl meltdown released more fissionable material with longer half lives

hiroshima bomb was detonated above ground and radiation was dispersed

hence, chernobyl responsible for more severe long term health effects such as cancer