A man and a woman have a daugp-ro;6 kbc /eehter and a son. Their daughter has normal vision, but their son iso 6; e/bpec-kr colourblind. Which one of these genotypes could be correct for the biological mother?

  Which diagram shows the sex chromosomes of a somat61(l gck;d+lfjqfu(x ic cell in a human male?

  There are two alleles for flower colour in snapdragons. However,p6vyj*u lgc 7 1b(ar1i the result of a cg(v7a1 bjpy*ir61uc lross between two heterozygous 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 t 2miv2usrevsl-5l4. vc *lne7 o the correct definition?

  Which of these statements is a correct defiuv 3o8v :6sg30og abmjnition for a gene?

  The diagram shows a pair i*z /bs:wr1ey2x+s n kof homologous chromosomes.

How many loci are shown?

  Two individuals, heterozygous for a specific trdg4vcp48 na6 k;(e (j5j6vyoxrere-g ait, were crossed in an experiment. Which row shows the expected phenotypic ratios of the offspring resulting fojy46e ( cdgvej8p;k g(56-xrvn r4earom this cross?

  In some animals, the agouti a3qwaz y; j; *vsuvkv;4llele causes individual hairs to have a banded pattern. The non-agouti q;zs4 awv *uykvv;3; jallele causes hairs to be a single colour. Individuals 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 indivzm t :unqft (ds4r g;lyv.75:hidual pea plants was either round orzq:g ul4tn7 .msrt5:y(v fd;h wrinkled. The results of an experimental cross yielded 315 offspring with round seeds 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 (Drosophila melanogaster) have 8 chromos9s0( 7ojqgof iomes. How many chromoi0q9s fo(g o7jsomes are in a fertilised oocyte of a fruit fly?

  When does the random orientation of homologous chro+1e2,dn6tksz ,(so;r h wtpch fl).jsmosome pairs occur?

The majority of the genes in the human genome hju-l *hh1 e6hqave already been mapped, meaning the exact locations of the genes on chromosomes are known. The diagram below shows one representation of a homologous pair of ch -6h 1ehhujq*lromosomes.

1.Define locus.

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

3.Distinguish between gene, allele, and locus.

  Which is the correct defifd1/n / thytga 1,mp,snition of linked genes?

  The diagram shows a karyogram of a brown male rat (Rattut v()x;-,gqlw/w ua exs norvegicus). Which arrow is pointing to a (xtlqe; w /xv ,-ug)wapair of autosomes?

  Mendel observed that there are two ln4zo gu; 0on8hzc)akz6s1*ppossible variations of flower colour in pea plants, purple and white. After a genetic cross, th 4zngolsa)18*nzoc pkz 6u0 ;he ratio of plants with purple flowers to white flowers is 1:1. What were the genotypes of the parents?

  The graph shows the frequency of birth weight of children 8v0lv rw7;eyixh1v) lborn in London in 1991.w 07e1 vl;vx)h ivly8r

  Which of these traits is an example of conl+ ( wvk-:1x*0) yt j)/oz g1jngbx;jccnagrktinuous variation?

  Which row correctly describes diploid and haploid cells in humanseje yfh (a86o x9 3mw28ef(ddt?

  The following table shows the diploid chroxpi2;eh d6e *:sr5kwumosome number of a range of species.

Which of these statements is correct?

  Sickle cell anaemia is cazyaht.w;,wlua,* 6lt used by a recessive 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 with blood type A had a cps2:xqdlghw zf(f 5,ee8l a /h)+yv/ahild with blood type O. What are the possible genotypef:8,qhw 5 )ylah/+gve2spl/f ae (xzds of the biological father?

  Which row shows the correct annotation of thkh:gl-8oi pw 0; 2g0 yfoeuujto450 sue alleles for blood groups?

  Which of these statements are true for alleles? / bqyfps / +8-rh4y, nphuwzy7
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 of ma (azu8f6fzunr,(p5 k tlaria across the 8(rt,pnzf(au z6ukf5 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), f vyc)*l-0 wx8 )*k:lpyw gnouwur colour is determined by a number of genes. Brown colour (B) is dominant to sandy colour (b) and an ombre (twx08 y:) *n* pw)gok ucvlwwy-lo 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 linkedn54y0l -uajf w and unlinked genes.

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

Sickle cell anaemia is caused by the at wo; / rtj+tc,*mu-zallele 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 brxs p ;.bpco;+paz0 /+wdv. his homozygous for brown, long hair and a female cat that has black, short hzdh + sw0p ;rpxo.+v/c.abb;pair.


Which of the offspring has a recombinant genotype?

  In dandelions (Taraxacum officinale), the allele for e9 m2)kdaysx+ diamond-shaped seeds (D) is dominant over oval-shaped seeds (d) and the allele for long seeds (L) is dominsxa2d m eky9+)ant over short seeds (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 hair (L) is dominant to short hair (tjxd o---oxg62z: xd .vx5 jrul), 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, straight-haired guinea pigs and a chi-squared test (χ2) was carried out on thoox 2ju:.v6j-d x gtzdr -x-5xe 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 pedigr7x zpxa v:3j srvcbm81;,79xzwl+ejvee chart be7abpv: ;ls9mxxz73v,j81j wc+v rex zlow?

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

  Which of these statements about genetic disorders is/aa)cc 0rs.kd2c;jt*wy - 9tfzure 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 normzqf68my rs- +hal distribution.

2.Outline the differences and similarities between homologous chromosomes.

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

  What suggests that the -kulzqoz5w a 0lb87o(inheritance of the disorder shown in the pedigree chart is X-linked recessive andz5w -a7u08(lqo kb ozl not autosomal recessive?

  Different species of living organisms have different numbers x4jgbzl 4n-/iwej .* yof genes characteristic to them. The table shows the estimated number of genes for fiviyzl/j.jn b4 g-4we*x e 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 characteristics of pea plantaw+ v*nd (r ymkbju-k03z) ;eds, including flower colour. If the pea plants Mendel was studying can only v;0ekyz)( wr kajdbu-n +d* 3mbe white or purple and follow the rules of Mendelian genetics, which of these statements was correct?

  A biological male with hemophilia and a biological female w7naqq- 0wh7byj4 2c rqithout hemophilia have a daughter without hemophilia. What are the possible genotypes of the daughtbc qa -w2n4j07qyq7rher?

  A dihybrid cross was cajw/d +nq f u)f5 /bi: rg)fqpda/s/4pvrried 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 s / p+ f/iaw:5r/4jdng/bqqsv) puf fd)ignificance level was 7.82. The calculated value for the chi-squared test was 10.05; what does this indicate?

1.Explain how parents with blood type A and 3bn o /iet:8vmxhg1p38b/h r pblood type B can have a child with b b/n3vt b 8:1/prhx mp8hoieg3lood type O.

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

3.Explain the role of inheritance in genetic diseases.