CBSE Class 12 (Science) Principles of Inheritance and Variation — practice questions
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Practice CBSE Class 12 (Science) Principles of Inheritance and Variation in the app →In Mendel's monohybrid cross of tall × dwarf pea plants, the phenotypic ratio in the F₂ generation wasA tall pea plant is crossed with a dwarf plant. Half the offspring are tall and half are dwarf. The genotype oThe genotypic ratio in the F₂ of a monohybrid cross between Tt × Tt isA cross between true-breeding red (RR) and true-breeding white (rr) snapdragons gives pink F₁ plants. This patA person with blood group AB has genotypeThe ABO blood-group system is an example ofThe phenotypic ratio in the F₂ of a Mendelian dihybrid cross (with two independently assorting genes) isMendel's Law of Independent Assortment is best illustrated by the F₂ ratioMorgan's discovery of linkage in Drosophila showed thatIf two genes on the same chromosome show a recombination frequency of 1%, they are approximatelyA trait controlled by three or more genes whose effects add up, producing a continuous range of phenotypes, isIn humans, the sex of a child is determined at fertilisation byIn honey bees, drones (male bees) develop fromHaemophilia and colour blindness are inherited asMendel conducted his classic genetics experiments using:In a monohybrid cross of Tt × Tt, the F2 PHENOTYPIC ratio is:In a DIHYBRID cross of YyRr × YyRr, the F2 phenotypic ratio is:In the human ABO blood group system, a person with blood group AB has the genotype:Sickle cell anaemia is caused by:Down syndrome is most commonly caused by:Haemophilia and colour blindness are MORE COMMON in MALES than females because they are:Mendel carried out his hybridisation experiments on:Mendel's experiments on peas ran for how many years?Mendel's work first applied to biology the tools of:Mendel's data carried greater credibility because his samples were:Mendel chose characters that showed how many opposing traits?A line showing stable trait expression over generations is called:Which pair of seed traits did Mendel study?The diagram used to work out cross outcomes is the:The Punnett square was developed by a geneticist from:The Punnett square calculates the probability of possible:In a monohybrid cross, the phenotypic ratio at F2 is:In that same cross, the genotypic ratio at F2 is:By the law of dominance, characters are controlled by units called:Mendel stated that these factors occur in:In a dissimilar pair of factors, the one expressed is called:The factor not expressed in a dissimilar pair is called:The law of segregation rests on the fact that alleles show no:During gamete formation, a gamete receives how many of the two factors?A homozygous parent produces gametes that are all:A heterozygous parent produces how many kinds of gamete?The phenotypic ratio from a dihybrid cross is:What does a true-breeding pea line show over several generations?Which contrasting pair describes seed shape in Mendel's pea plants?Which pea character has the contrasting traits inflated and constricted?What is the first hybrid generation of a cross called?When Mendel crossed tall and dwarf pea plants, what were the F1 plants?What fraction of Mendel's F2 pea plants from the tall x dwarf cross were dwarf?What name is now given to the 'factors' that Mendel proposed?Genes coding for a pair of contrasting traits are known as what?In Mendel's notation, which symbol is used for the trait expressed in F1?The descriptive terms 'tall' and 'dwarf' describe which feature of a plant?A plant heterozygous for one character, such as Tt, is called a what?In the F2 of a Tt x Tt cross, what fraction of plants are heterozygous Tt?A test cross is made between an organism with a dominant phenotype and which parent?Why did Mendel cross a tall F2 plant with a dwarf plant?According to the law of segregation, how many alleles of a pair does a gamete receive?What gametes does a heterozygous parent produce?Flower colour in snapdragon (Antirrhinum) is a good example of what?A true-breeding red snapdragon crossed with a white one gives what F1 colour?What phenotypic ratio results in the F2 of a snapdragon red x white cross?In co-dominance, the F1 generation resembles which parent(s)?The ABO blood group in humans is controlled by a gene with how many alleles?What does the allele i of the human ABO gene produce on the red blood cell?How many different genotypes are possible for the human ABO blood types?What seeds did Mendel get in F1 from yellow round x green wrinkled peas?The 9:3:3:1 ratio is a combination of which two monohybrid ratios?According to the law of independent assortment, segregation of one pair of characters is what?How many types of gametes does an RrYy plant produce?In the dihybrid F1 RrYy, what percentage of gametes are RY?Who independently rediscovered Mendel's results in 1900?Which two scientists noted that chromosomes behave parallel to genes?Which organism did Morgan use in his studies of inheritance?Which term did Morgan coin for the physical association of genes on a chromosome?What term describes the generation of non-parental gene combinations?When two genes lie on the same chromosome, which gene combination is more frequent?What recombination frequency did the white and yellow genes of Drosophila show?Which gene pair of Drosophila showed 37.2 per cent recombination?Who used recombination frequency to map gene positions on a chromosome?Tightly linked genes show what level of recombination?Traits controlled by three or more genes are called what?Which human trait is a classic example of polygenic inheritance?In polygenic inheritance, how do the effects of alleles combine?What is it called when a single gene shows multiple phenotypic expressions?What did Henking name the nuclear structure seen in only half the sperm?In XO type sex determination, as in grasshopper, how many X chromosomes do males have?In humans and Drosophila, which sex is homogametic?In birds, which sex chromosome pair do the females have?What decides the sex of a human child?What is the chance of a male child in each human pregnancy?A male honey bee (drone) develops from what kind of egg?How many chromosomes does a haploid male honey bee have?What is a mutation?Which classical disease is an example of a point mutation?Deletions and insertions of base pairs of DNA cause which type of mutation?What are chemical and physical agents that induce mutations called?The study of a trait across several generations of a family is called what?Mendelian disorders are mainly caused by alteration in how many genes?Colour blindness is what kind of disorder?About what percentage of males show red-green colour blindness?What happens in haemophilia, a sex-linked recessive disease?Whose family pedigree showed many haemophilic descendants due to a carrier?Sickle-cell anaemia is inherited as which type of trait?In sickle-cell anaemia, which amino acid replaces glutamic acid in the beta globin chain?Which genotype shows the diseased phenotype of sickle-cell anaemia?What chromosome constitution does a person with Turner's syndrome have?What is the karyotype in Klinefelter's syndrome?The gain or loss of a chromosome due to failure of chromatid segregation is called what?Failure of cytokinesis after telophase leads to which condition, common in plants?Who first described Down's syndrome, in 1866?