A man and a woman have a daughter and a son. Their daug(6-( xo6 s(mvcjiosje hter has normal vision, but their son is col 6(-mocsj 6sv(oe(i xjourblind. Which one of these genotypes could be correct for the biological mother?

  Which diagram shows the sex g5 wx2/cbkmi7:gm 4w 9xzolh -*pin6mchromosomes of a somatic cell in a human male?

  There are two alleles for flower colour in snapdragons. However, the result ofobbw *u9zy g77 a cross between two heterozygous plants yielby9 zw7gb7u* oded offspring with three different observed phenotypes, red, white and pink flowers. Which is the most likely explanation for this observation?

  Which keyword is mat00w *k.m3lqe,zln qy vched to the correct definition?

  Which of these statements ifmk0 ;l1fj*tpchv 0:ns a correct definition for a gene?

  The diagram shows a ppwy;te yv, qq.c*i) 2pair of homologous chromosomes.

How many loci are shown?

  Two individuals, heterozygou7hve* qwb7n3 ms for a specific trait, were crossed in an experiment. Which row shows the expected qhm 77 *ebnvw3phenotypic ratios of the offspring resulting from this cross?

  In some animals, the agouti al4cmt7 cp:esn* lele causes individual hairs to have a banded pattern. The non-agouti allele causes hairs to be a single colour. Indivim74ecn*spc :t duals 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 individual pea pla aq,7zcgov2 h6um; /aants was either round or wrinkled. The results of an experimental cross yielded 315 offspring with round seeds and 10,6v z;m /ho u7caq2aga5 offspring with wrinkled seeds.

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

  Neurons of the fruit fly (Drosoph4m s qx6spg5)brsoj rkq .+k)+ila melanogaster) have 8 chromosomes. How many chromosomek +pjm)+5kq4qsgos6rs b. x) rs are in a fertilised oocyte of a fruit fly?

  When does the random orientation of homologous chromos *j wxp(lrkys 4ek*u:6ome pairs occur?

The majority of the genes in the human genome havewn9);a 4drfp t already been mapped, meaning the exact locations of the genes on chromosomes are known. The diagram below shows one repre waft4n ;pd9)rsentation 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 definition oo-jctz5 0 gc .5lqtuc3f linked genes?

  The diagram shows a karyogram of a brown male rat (Rattus norvegicus). W e)8giv2thot v7fz9y* a/wd,uhich arrow is pointing to a pair off,htea2)g7t 9dyowv/ uzi8 *v autosomes?

  Mendel observed that there a4 cnhgh6733vkp1j r.bnlup m6k:t0l(ptz ,b w re two possible variations of flower colour in pea plants, purple and white. After a genetic cross, the ratio of plants with purple flowenh7l k .rtbp3m3w h60bj 4pn6tul:(k1 pz,vcgrs to white flowers is 1:1. What were the genotypes of the parents?

  The graph shows the frequen+t vyf5m5a e, m.vcam8cy of birth weight of children born in London in 1991m+ ac,t8ymv f55e.mv a.

  Which of these traits isl 7 5)9xzuhxnt an example of continuous variation?

  Which row correctly describes diploid and 7bp5m+m s-yl ahaploid cells in humans?

  The following table shows the3teg48 dh*+w(m dyx lt diploid chromosome number of a range of species.

Which of these statements is correct?

  Sickle cell anaemia is caused by a recessive allele (Hm l ylx7rs2mb*v(; tn/b$^S$). 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 with blood type A had a child with blood type O. Whatxh3 m))),5 zv-v *qhxkpf uicxib a;(*2lzsbz are the possible genoty,bf;ah 2)s xm ixh3vzclxbz(u-5vk)i q)*p*z pes of the biological father?

  Which row shows the correcwd9d +2 yd bh8uwf m;;1 7nrnynk*/kuct annotation of the alleles for blood groups?

  Which of these statements are true3:1 pm70xc 4x6hua 9dvrni)rfmn2p cq 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 thn)r- st fwyky ,,13knue spread of malaria across the continent of A3k kt fuy1,s,nnr)-ywfrica.


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 (Equut:v8yb. 3khk m dbo4 m:h;fh5is przewalskii), fur colour is determined by a number of genes. Brown colour (B) is dominant to sandy colour (b) and an ombre (two tone) c;ih f:k3:8hd 5 .yo4 mkmvbhtbolour (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 betweenl 8z14) sock3gttgua. linked and unlinked genes.

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

Sickle cell anaemia is caused by the + qt+vc/48 .xqczpbwnallele 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 shqa0wmw.m k602kd xia(ows a cross between a male cat that is homozygous for brown, long haiai ad0 0m2kxq6m (ww.kr and a female cat that has black, short hair.


Which of the offspring has a recombinant genotype?

  In dandelions (Taraxacum offg 37yxx04hn z7z sle8kicinale), the allele for diamond-shaped seeds (D) is dominant over oval-shaped seeds (d) and the allele for long seeds (L) is dominant over short seed 77lzxny3g k4e0 s8zxhs (l).

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 hairb:gep,jpdc c 7jbb9xp85i 9 f; (L) is dominant to short hair (l), and curly hair (C) is dominant to straight hair (c). A test cross was carried out between male heterozygous long, curly-haired guineabgcedi9pp:px jcjf5987;,b b pigs and female short, straight-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 the condition shown in the pedo(6jm0wft s9 higree chart belom 0h6ts9(ofwj w?

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

  Which of these statements about genetic disord7-0f qxtn+hrcmcg r6 :ers 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 can show a normal distributin249kimeei7( 0 ka 5hn5qrsep on.

2.Outline the differences and similarities between homologous chromosomes.

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

  What suggests that the inheritance of the disorder sha3*twbn 0ve9s own in the pedigree chart is X-linked recessive and not autosomal recessiv309a bnvwt *ese?

  Different species of living organisms have different numbers of ge:18k:q, qsimh gjat f.nes characteristic to them. The table shows the estih8 g:,ktqqs 1:j ma.fimated 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 characterist+4 8m,fogvzw tics of pea plants, including flower colour. If the pea plants Mendel was studying can only be white or purple and follow the rules of Mendelian genetics, which of these statements was correct g8t,vz4 +fwom?

  A biological male with hemophilia and a biological8ob wq5(vk vs76zwri5;x zn;yszk 5z2 female without hemophilia have a daughter without hemophilia. What are the possible genoty256 (or zi kk;sz;x 8n55bwzzvqywsv7pes of the daughter?

  A dihybrid cross was carrieu( jx*g co re+5x3jw*xd out between two sunflower 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 calculatexgr + 3e(cu*xw*jxjo5d value for the chi-squared test was 10.05; what does this indicate?

1.Explain how parents with blood type A and bl *m uc+uv7ow5tood type B can have a child with btvu +7mo cw5*ulood type O.

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

3.Explain the role of inheritance in genetic diseases.