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The correct OPTION is (C) 9:3:3:1

Easiest EXPLANATION: The phenotypic RATIO obtained by the dihybrid cross is 9:3:3:1 while that by a monohybrid cross is 3:1. The GENOTYPIC ratio of a monohybrid cross is 1:2:1 while the genotypic ratio of dihybrid cross would be 1:2:1:2:4:2:1:2:1.

The correct answer is (c) Colour of flower and seed coat

Easy EXPLANATION: Flower colour i.e. WHETHER it will be purple or WHITE and seed coat colour whether it will be GRAY or white is determined by the same GENE.

The correct option is (d) 4/16

The explanation: In this CASE, all of AA BB, AA bb, aa BB and aa bb will breed true. This MAKES 4 out of 16 being true breeding. In a PUNETT square these are along the DIAGONALS.

Right answer is (b) 20

Best EXPLANATION: Here the parents are heterozygotes so the ratio of the progeny will be 1:2:1 for WHITE: Andulasian: black. If there are 10 white then according to the ratio there should be 20 Andulasian fowls produced. If we consider the NUMBER of black fowls that WOULD be 10.

The correct option is (C) All same

The BEST I can explain: Both the phenotypic and genotypic ratio will be the same i.e. all will be heterozygous for H LOCI and T loci. In this CASE, it will express the dominant trait in both cases.

The correct CHOICE is (a) Pisum sativum

Explanation: GARDEN pea or Pisum sativum was used by Mendel for his EXPERIMENTS. This was because he OBSERVED many DISTINGUISHABLE characteristic traits in it and it could be easily grown and self pollinated.

Correct choice is (C) tt pp X TT PP

For explanation I WOULD say: In case of this cross although one is homozygous recessive the other is homozygous dominant, so all the PROGENY will be heterozygous EXPRESSING the dominant trait. In case of TT Pp X tt pp the recessive trait can be seen in case of P locus.

Right option is (d) 10

For EXPLANATION: ACCORDING to normal dominant/ recessive relation the ratio between red and white flowers should be 3:1, but in the case of snapdragon where the heterozygous has a different phenotype pink the ratio changes to 1:2:1 for red: pink: white. Thus the EXPECTED NUMBER of red is 10.

The CORRECT choice is (c) Cross between homozygous recessive and heterozygous

Explanation: Considering the two phenotypes having genotype Hh and hh (H being DOMINANT), the f1 must have PHENOTYPE Hh and hh, and so will the parent ALSO have a phenotype HN and hh. This is like a repeated test cross.

Correct answer is (B) R locus

Easiest explanation: The organism has a homozygous RECESSIVE phenotype for the R locus, thus it can be used to test CROSS other ORGANISMS for R locus.

The correct CHOICE is (d) Purple vestigial and red vestigial

Explanation: In this CASE, drosophila SHOWS the linkage between these two GENS, so the parents must having the trait that is mostly PRESENT in the offspring.

Correct OPTION is (a) True

Best explanation: In a branched diagram the next PHENOTYPE could be processed by adding ONE column or branch, but in case of Punett square considering greater than 2 alleles would include a huge table which is quite hazardous to handle.

Right option is (d) Hh X hh

To ELABORATE: While back cross is crossing the progeny with any of the parents, test cross is PERFORMED by crossing the F1 progeny with the double RECESSIVE parent. The others are EXAMPLES of back cross except option a.

Correct choice is (d) Concept of chromosomes

The explanation is: ALTHOUGH Mendel SUCCESSFULLY DISCOVERED the concept of inheritance of genes, and their inheritance with dominant recessive RELATIONS; it was Sutton and Boveri to GIVE the chromosomal concept of inheritance.

Right option is (a) Law of segregation

The best explanation: Law of segregation states that the ALLELOMORPHS don’t bland and lose their identity but they remain TOGETHER until the FORMATION of GAMETE when they segregate into different gametes. There is no Law of recessive; it’s just a PART of law of dominance.

Correct ANSWER is (d) Independent assortment

Easy explanation: DUE to linkage parental chromosomes will have a tendency to be inherited together, thus the GENES will not reasonably assort independent of each other. PANSPERMIA aw is by Darwin.

Right choice is (d) TERMINAL flower

To explain: All of the 1^st three OPTIONS represent the dominant trait, while the option of terminal flower is RECESSIVE to flower in AXIAL POSITION.

Correct answer is (c) 1/16

Explanation: In this case we have to consider ONE ALLELE pair at a time. Probability of a heterozygote from F1 cross is ½ and homozygote is ¼. THUS here it will be 1/2X1/4X1/2= 1/16 for Aa BB and Cc respectively.

Correct answer is (B) Two

For explanation I would say: Multiple allele STATES that there can be more than one or even more than 2 ALLELES for one GENE, but one organism can have only 2 such alleles as there are 2 loci only.

Right OPTION is (c) 1/4

Best explanation: In this case the FATHER is heterozygous as Rr and mother is homozygous recessive rr. Considering the probability of a GIRL child being ½ we have the probability of a roller as ½. resulted is the product of these TWO PROBABILITIES ½ x ½ = ¼.

Right OPTION is (c) Bb BB and bb

The explanation: Brown mouse is HOMOZYGOUS RECESSIVE so this is sort of a test cross for the female mice. As mouse A has both black and brown progeny, it must be heterozygous. And within his litter size, we can say that B is expected to be homozygous BB.

The correct option is (d) 2/3

Explanation: Here we are ACTUALLY SELECTING the plants which are heterozygous for the trait as in Hh. Only selfing these will give both dominant and recessive trait in next generation. As we are not taking hh into CONSIDERATION the RATIO resulting is 2/3.

Correct CHOICE is (b) All tall

To EXPLAIN I WOULD say: In this case tall is the dominant trait. Then all the F1 progeny will be heterozygotes where the dominant phenotype tall is expressed.

The correct OPTION is (B) 1/16

For EXPLANATION I would say: In this case, the probability of each of the locus producing a recessive ALLELE is multiplied. That would be ½ X ¼ X ½ for A, B and C locus respectively.

The correct ANSWER is (C) 2:1

The explanation: Homozygous yellow rat YY is lethal, so the parent MUST be heterozygous Yy. Now, the living PROGENIES will be Yy and yy i.e. yellow and white in the ratio 2:1 and YY will be lethal.

The correct option is (b) 42

To elaborate: This is a CASE of a test cross for the Height allele. The ratio should be 1:1 for short: tall. If there are 41 tall progeny there must be a SIMILAR number SAY 42 of short ones.

Right choice is (d) NORMAL RATIO

The best I can explain: If the ratio of the progeny is calculated it is very CLOSE to 9:3:3:1 which is the ratio of normal digybrid CROSS.

The correct option is (b) HH Rr

To explain: In this CASE of HH Rr it will be true breeding for H locus but as it is heterozygous for R locus, R CHARACTER will not BREED true. On the other hand HH RR and hh rr will breed true for both the H and R CHARACTERS.

Right answer is (c) Flower colour and SHAPE of pollen grain

Best EXPLANATION: Mendel did not STUDY pollen shape and flower colour INHERITANCE together, as if he would have USED these traits in dihybrid cross they would show linkage and tamper his results.

The correct choice is (b) 2

To explain I would say: If a GENE is heterozygous it will have two different alleles for the same gene, THUS in case of monohybrid CROSS where only a SINGLE gene is considered maximum two alleles are under consideration. For dihybrid cross the number will be 4.

Correct choice is (d) No ratio

Easiest EXPLANATION: Cross between QQ and qq will always result in Qq which is LETHAL. This prevents generation of any heterozygote or rather any progeny by MATING of these TWO bats.

Correct answer is (c) 3:1:3:1

Explanation: In this cross the ratio WOULD be as follows 3(tall PURPLE): 1 (tall WHITE): 3 (short purple):1 (short white). This is a test cross for height GENE but not for colour gene.

The CORRECT choice is (b) Andulasian

The best explanation: FEATHER colour in fowls show an incomplete dominance relation where the WILD types are WHITE and black and HETEROZYGOTES generated by their mating are Andulasian.

Correct OPTION is (c) 1:1 RECESSIVE; dominant; all dominant

The explanation is: Test cross with a double recessive parent and a homozygous dominant will GIVE all heterozygotes, which will express dominant TRAIT. On the other hand heterozygotes will give 1:1 heterozygote: homozygote which will express dominant: recessive.

Right answer is (b) His experimental model being rare

To elaborate: GARDEN pea was an excellent model which was not only readily AVAILABLE but ALSO easy too be GROWN and carry out experiments on. However, the other reasons as mentioned SERIOUSLY contributed at Mendel not becoming an instant success.

Right answer is (d) Both PARENTS are short

Explanation: PURE recessive traits like short PLANT height can be produced by HETEROZYGOTE crossed as well, but we can say this with confirmation only when we have true breeding recessive parent plants.