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2 heterozygotes?2) From a dihybrid cross of AaBb to AaBb, where A and B show complete dominance to a and b and independent assortment. How many of the 16 possible combinations would be heterozygous for both alleles?
3) From a cross between Aa and Aa, where A has complete dominance to a, how many of 160 offspring will be phenotypically recessive?
4) Haemophilia is a sex linked recessive characteristic. a. For a cross between a carrier female and a male with haemophilia, assuming they have 4 children, what would be their sex, phenotype and genotype in relation to haemophiliab. How would this change if the female was homozygous dominant?
5) For a mating between two normal winged Drosophila, 54 dumpy-winged and 159 normal-winged offspring were produced:a. What is the nature of the dumpy-wing gene?b. What were the parental genotypes?
6) In pea-plants the flower colour and height are determined by independently assorted alleles that both show complete dominance of tall over dwarf and red over white. Two flowers were crossed and the following offspring were given:552 tall, red : 182 dwarf, red : 187 tall, white : 62 dwarf, whiteWhat was the genotype of the parents?
7) For a bird neither the allele for brown or white feather is dominant, with the heterozygote giving a grey feather. If a grey **** is mated with a grey hen then what is the probability that from a clutch of 4 eggs, that there is will 2 brown feathered, 1 white feathered and 1 grey feathered bird.
8) If a mother has a blood group B and has a son with blood group AB, what are the possible genotypes of the mother and of the father?
9) In mice the gene for a coloured coat (C) is dominant to the gene for albino (c). If two heterozygous mice are mated and there are 12 offspring? How many of them will be phenotypically albino and how many will have the parental genotype?
10) How many phenotypes result from a cross between two heterozygous parents when there is monohybrid incomplete dominance of the alleles (Rr)?
11) From a dihybrid, 2 trait cross with independent assortment when both parents are heterozygous (RrSs) and there is complete dominance, what is the ratio of different phenotypes that can be given. (R & S dominant feature) : (R dominant feature, s recessive feature) : (r recessive feature, S dominant feature) : (r and s recessive feature)
12) A homozygous dominant purebred rabbit for normal size and black colour is crossed with a homozygous recessive purebred dwarf, albino rabbit. The resulting offspring (F1 generation) breed with each other to give the F2 generation. What proportion of the offspring would be expected to be:a. Albino?b. Normal size?c. Homozygous dominant for both alleles?
13) Blood groups are inherited in a codominant manner. If the mother is IBIo and the father IAIo, what is the probability that a child being blood group IoIo?
14) Blood groups are inherited in a codominant manner. If the mother is IBIo and the father IAIo, what is the probability that a child being blood group IAIB?
15) Red-green colour blindness is a sex-linked recessive condition. What would be the genotype and the phenotype ratios of offspring from a red-green colour blind mother with a normal father?
16) What is the term for the selection situation that would favour most individuals having a narrow range of a particular feature e.g. all being a similar colour fur?
17) Explain how comparative anatomy can be used as evidence of evolution.
18) The Hardy-Weinberg equation is p2 + 2pq + q2 =1, using this equation determine the percentage of the population that will be carriers for a recessive disease in which 1 in 2500 births have the disease.
19) Briefly (no more than 40 words) explain the founder effect.
20) Achondroplasia, a form of dwarfism, and is a dominant disorder, with homozygous dominant individuals not surviving. Give the genotype and phenotype of the offspring of parents who are both heterozygous for dwarfism.