A man and a woman have a daughter and a son. Their daughter has normal23z 6fa5xzkii vision, but their son is colourblind. Which one of these genotypes could be correct for z5zfi i23x 6kathe biological mother?

  Which diagram shows the sex chromosomes of a somatic cell v8o miqq) jv6ii 4iy*0in a human male?

  There are two alleles for flower colour in snapdragons. Hl0jo *iq 0cb1towever, the result of a cross between two heterozygoust o *ql01bcji0 plants yielded offspring with three different observed phenotypes, red, white and pink flowers. Which is the most likely explanation for this observation?

  Which keyword is matched to t0wai 2q1 ,mz6qe 6yab:mod17ayup)lzhe correct definition?

  Which of these statements is a correct definition for a ge; ,7o9qr cr 4syaxarr;ne?

  The diagram shows a pair of homologous chrag8;hapxg48j 7 d xbu,omosomes.

How many loci are shown?

  Two individuals, heterozygous for a specific trait, were crossedpizb *;:w64ku :ezau: j ,8m/ fwmjzpi in an experiment. Which row ji:,:uamze/4pb; j6u w zfiwkm:*zp8 shows the expected phenotypic ratios of the offspring resulting from this cross?

  In some animals, the agouti allele causes individual hairs to ha :fhvpmeeqejs0 +odw0r hi k/p5;( 8y7ve a banded pattern. The non-agouti allele causes hairs to be a single colour. Individuao;p+e8d0 7m j5qefkvh0(wi:sy hp re/ls who are heterozygous have hairs with a banded pattern.

Which combination of parent genotypes would allow for production of offspring that do not have the agouti characteristic?

  Mendel observed that the seed shape in 0e cdywx;1 ;jo1/mhhbindividual pea plants was either round or wrinkled. The results of an experimental cross yielded 315 offspring with round m heody;w1h; /01bjc xseeds and 105 offspring with wrinkled seeds.

Which row in the table below states the most likely genotypes of the parents?

  Neurons of the fruit fly (Drosophil6 k)ktn5l 3amz/fl uj;.3qnt ba melanogaster) have 8 chromosomes. How many chromosome3.5n ;/lanqjuf6tz lk3)mk tbs are in a fertilised oocyte of a fruit fly?

  When does the random orientation of homologousl(+4 owbrxiymn w-s 3: chromosome pairs occur?

The majority of the genes in the human genome have alr.-5b5un)t tjxef (eseeady been mapped, meaning the exact locations of the genes on chromosomes are known. The fet(sn 5j.bxt-uee5 ) diagram below shows one representation of a homologous pair of chromosomes.

1.Define locus.

2.Identify the number of loci shown in the diagram.

3.Distinguish between gene, allele, and locus.

  Which is the correct defxmc.457u,vt;jw2e0 o16 rarv vhp oruinition of linked genes?

  The diagram shows a karyogram of a brown male r pmvo xliyh)o+4xv(*, uhe vr /enj/-5at (Rattus norvegicus). Which arromv5e(o/ )-*hhe 4plv, +v nxuiroyjx/ w is pointing to a pair of autosomes?

  Mendel observed that there are two possible variations of flower colour in pe:*mbtn0riv n53md5b na plants, purple and white. After a genetic cross, the ratio of plants with purple flowers to white flowers is 1:1b5 nm 35td0rmv*bni n:. What were the genotypes of the parents?

  The graph shows the frequi+ l( * - -pgxbtsysa zcwmx3-0nqvo33ency of birth weight of children born in London in 1991wpb t 3-l3+q(vxnzm-xo-acsy0gi s*3 .

  Which of these traits p 3nxkp)q 7mu/+qyh(uis an example of continuous variation?

  Which row correctly describes diploid and hapl99hg(qz3 3opbhcxt-nd5p w7.l7p xfzoid cells in humans?

  The following table shows the diploid chromosome n2,kjml 4cf*zi y8*kl iumber of a range of species.

Which of these statements is correct?

  Sickle cell anaemia is caused by a recedlo nvz7/:6pxthx tho u 00+)sssive allele (Hb$^S$). The dominant allele is Hb$^A$. This image shows the inheritance of sickle cell anaemia in a family.

What are the genotypes for individuals 1 and 7?

  A biological female fh u:9-1 zmz a:cxrwv:with blood type A had a child with blood type O. What are the possiblevrwhxa:9z:1f- : uczm genotypes of the biological father?

  Which row shows the correct annotation of the a1;o6 mccu.lfb4t xdhe j61i y3l 2rm7slleles for blood groups?

  Which of these state+x*m *yc obyq ir,)lu8ments are true for alleles?
I. Alleles are versions of a gene
II. Alleles differ by one or more base
III. Alleles affect the same characteristic

The maps show the incidence of sickle cell anaemia and the spread ogx9ho.m5u daz53 vkeum8jt):ju. u: ju:u c1 zf malaria across th. 1x)5uju3uzm9cd5: um:z8uj hkuae: v g.jote continent of Africa.


The graph shows the average density of malarial parasites present in the blood of Hb AA (not affected by sickle cell anaemia) and Hb AS (carriers of sickle cell anaemia) people in Sub-Saharan Africa.

1.Compare and contrast between the distribution of sickle cell trait and malaria in Africa.

2.1.State the mode of inheritance of sickle cell anaemia.

2.2.Using a genetic diagram, determine the probability of a child having sickle cell anaemia, if both their parents are carriers of the disease.

3.Blood samples were taken from children to create the graph. Suggest one difference between the appearance of blood cells in Hb AA and Hb AS samples.

4.State at which age there is the largest difference between the number of parasites found in the blood of Hb AA and Hb AS samples.

5.Suggest one difficulty of collecting sufficient data for this study.

6.Using your own knowledge and the data provided, discuss whether carrying the sickle cell allele offers protection from malaria.

In Mongolian horses (Equus przewalskii), fur colour is determined bn (ui igi;wk/bp.x):ky a number of genes. Brown colour (B) is uin . ;wbg/:p()i ixkkdominant to sandy colour (b) and an ombre (two tone) colour (P) is dominant to one tone (p).


1.A homozygous sandy ombre male horse is crossed with a heterozygous horse for both traits. Draw a Punnett square to show the potential results of this cross.

2.Identify the possible genotype recombinations, after fertilisation, from the cross in part (a).

3.In pigs, the curly tail is dominant to the straight tail, and pink skin is dominant to black skin. On a pig farm, the resulting phenotypes from double-heteroygous genotype breeding were recorded. The chi-square value for the phenotypes of the offspring was calculated and the result was 340.6.
The table below shows the degrees of freedom (D.f.) and critical values at a significance level (p) of 0.05 (5%) for a chi-squared test.
Discuss whether the genes for skin colour and tail shape in pigs are linked or unlinked.

1.Distinguish between linked and unlinked geneszte* b4,wxg dfn3) x612i dbevm0a*bd.

2.Coat colour is a polygenic trait. State the meaning of polygenic.

Sickle cell anaemia is caused by the allelz; 10oqudymu,xd.c w2;b ()ienlk ok4e Hb$^S$ . The normal allele is Hb$^A^ .

1.Identify the genotype of individuals 1 and 2.

2.Predict the probability of individuals 5 and 6 having another child that is unaffected. Justify your answer.

3.If individual 7 had a child with an affected biolgical female, identify the possible genotypes of the child. Justify your answer.

4.Deduce, with evidence, the pattern of inheritance of sickle cell anaemia that is shown in this pedigree chart.

5.Distinguish between sex-linked inheritance and autosomal inheritance in humans.

  The diagram below shows a cross between a male cat that is homozygous for brow;t q:+(iedfjh n, long hair and a female ctied: q+ hjf(;at that has black, short hair.


Which of the offspring has a recombinant genotype?

  In dandelions (Taraxacum officinale), the allele for ig5.t )0lzqjp diamond-shaped seeds (D) is dominant over oval-shaped seeds (d) and the allele for long seeds (L) is dominant over short seeds (l)gq) .z50jltpi.

In a genetic cross between a dandelion that is heterozygous for both traits and a dandelion that is homozygous recessive for both traits, what would be the expected proportion of long seeds?

In guinea pigs (Cavia porcellus), long hair (L) is dominant to shoxkfb 4q+cpfu j2(k/ 59(p oeufrt hair (l), and curly hair (C) is dominant to straight hair (c). A test cross was carried out between male heterozygous long, curly-haired guinea pigs and female short, strax fjo 45 /u(pue+fkp2 (fck9qbight-haired guinea pigs and a chi-squared test (χ2) was carried out on the offspring.



1.1.Using a genetic diagram, state the expected ratio of the cross between the two parents.

1.2.Identify the recombinants.

2.1.Calculate the ratio of the observed phenotypes.

2.2.Suggest a reason for the difference between the expected and observed ratios.

3.1.State the null hypothesis in this study.

3.2.Deduce with reasons whether the null hypothesis should be accepted.

  What best describes the inheritance of;;ndazrg.5/kua h/ ix the condition shown in the pedigree chart belo/knad5. uz;h;x g /airw?

I. Sex-linked trait
II. Dominant trait
III. Recessive trait

  Which of these statements1d9flxe*2w r t about genetic disorders is/are correct?

I. The majority of genetic disorders are caused by recessive alleles.
II. Genetic disorders can be sex-linked.
III. Offspring of two parents with the same genetic disease will always be affected.

1.Outline how polygenic traits canu-xp)jays: l * show a normal distribution.

2.Outline the differences and similarities between homologous chromosomes.

3.Explain why expected and observed Mendelian ratios may differ.

  What suggests that th+580mkmjrjzsl w nlo/kn i3762jrq2ye inheritance of the disorder shown in the pedigree chart is X-linked re ikj+3 w2 nnj zr0r2ll65m/jyqo78ms kcessive and not autosomal recessive?

  Different species of living organisms have different numbers of ax rr/8. -birihr,b8x genes characteristic to them. The table sho iarrxbi 8xb8-./r, rhws the estimated number of genes for five species.
Species Estimated number of genes
Escherichia coli (bacteria species) 4,000
Drosophila melanogaster (fruit fly) 13,000
Canis lupis familiaris (dog) 20,000
Homo sapiens (humans) 30,000
Oryza sativa (rice) 40,000
1.Using the information in the table deduce the estimated number of loci in a human genome.
Estimated number of loci in a human is   .
2.Explain how a mutation can affect a characteristic.

  Mendel studied eight chhs2k7x o)81y kcpzj 4v qmt/w;aracteristics of pea plants, including flower colour. If the pea plants Mendel was studying can only be white or purple and follow the rules of Mend)v4 y8tz7 wpcqo smk;h1j/2kxelian genetics, which of these statements was correct?

  A biological male with hemophilia and a biological fem,paq3ax- 5 /eb5vsd ryale without hemophilia have a daughter without hemophilia. What are the possible genotypes of thpvesya ad -b5/x,rq5 3e daughter?

  A dihybrid cross was carried out between two sunflowm(hm0hjt*s ; aer plants (Helianthus annuus) to see if the genes for seed number and seed shape are linked. The critical value for the chi-squared test at the 0.05 significance level was 7.82. The calculated value for the chi-squared test was 10.05; wj m;*ha (t0hmshat does this indicate?

1.Explain how parents with blood type A and blood type B canbkqe sm7 a:q6mp/4ydtj0+5z n have a child with b/:+ad7tbey 0 s 6jqz pnk54qmmlood type O.

2.Outline how polygenic traits can show a normal distribution.

3.Explain the role of inheritance in genetic diseases.