What is the role of genetic counselling in the eradication of geneticdisease from the society? Black-smooth hair is produced in F₂ generation resulting from a cross between pure black-rough haired guinea pig (BBRR) and pure white-smooth haired guinea pig (bbrr). Show their possible genotypes and genotypic ratios with the help of a table. [3 + 2]
Genetic counselling detects carrier status in parents for autosomal recessive diseases like thalassemia (heterozygous parents have 25% chance of affected child, 50% carriers). Counsellors advise risks, recommend prenatal testing or avoiding marriage between carriers, preventing birth of homozygous affected children. This reduces disease incidence across generations, eradicating it from society by breaking transmission cycles, as in thalassemia where heterozygous couples are warned.
Parental (P) Generation
| Parent | Genotype | Phenotype |
|---|---|---|
| Pure black, rough | BBRR | Black, rough |
| Pure white, smooth | bbrr | White, smooth |
F₁ Generation
|
BbRr (Black, rough) |
BbRr (Black, rough) |
BbRr (Black, rough) |
BbRr (Black, rough) |
Punnett Square (F₂ Generation)
| × | BR | Br | bR | br |
|---|---|---|---|---|
| BR | BBRR | BBRr | BbRR | BbRr |
| Br | BBRr | BBrr | BbRr | Bbrr |
| bR | BbRR | BbRr | bbRR | bbRr |
| br | BbRr | Bbrr | bbRr | bbrr |
More WBBSE Moderate level questions
Mention the dominant and recessive traits of two characters related with seed and one character related with flower of pea plant. Very often it is experienced that a colour-blind son is born to apparently normal parents. Show with the help of a cross how it happens.
Column–A Column–B 2.13. ADH (a) Decline in Wetland 2.14. Amitosis (b) Convergent Evolution 2.15. Thalassaemia (c) Palash (Flame of the forest) 2.16. Analogous organ (d) Spindle fibre is not formed 2.17. Increase in human population (e) Decreases the volume of urine through reabsorption of water from the distal convoluted tubule of nephron 2.18. Ontholiphonus flower of Paddy (f) Paddy (g) Recessive Mutant gene located on Autosome
In which of the following crosses, will the F1 generation seed's tall and dwarf traits appear in a 1:1 ratio? (a) Tt x Tt (b) TT x Tt (c) TT x tt (d) Tt x tt
What will be the phenotypic ratio of progeny obtained from the hybridization between YyRR and YYrr genotypes? (a) 2:1 (b) 1:2 (c) 2:2 (d) 1:4
If a population undergoes three generations, and if each generation consists of only males, what is the probability that females will be present in the fourth generation? (a) 100% (b) 0% (c) 50% (d) 75%
Match the words in Column A with the most appropriate words in Column B and rewrite the correct pair mentioning the serial no. of both columns (any five): [1×5=5] Column A Column B 2.13 Adrenaline (a) Air Pollutant 2.14 Self pollination (b)According to Haldane the hot marine water containing different organic compounds 2.15 The position of flower is axial (c)The adoloscent phase of human development 2.16 Hot Dilute Soup (d)No need of agent 2.17 SPM (e)The senescence phase of human development. 2.18 Britleness of bone and pain at bone joints (f) Increases heart beat, cardiac output and blood pressure. (g) Dominant trait
With the help of a checkerboard show the phenotypic ratio of offspring produced in F2 generation as a result of a cross between a pure black coloured and rough-haired guinea pig and a pure white and smooth-haired guinea pig. "Father plays the main role in the determination of sex of the offspring" - justify the statement with the help of a checkerboard. [3+2=5] OR Write three reasons behind Mendel's success. Establish a relationship between phenotype and genotype with the help of proper examples. [3+2=5]
Match the words in column-A with the most appropriate words in column B and re-write the correct pair mentioning the serial no. of both columns COLUMN - A COLUMN - B 1. Meninges (a) Decrease in the number of digits in the legs 2. Sexual reproduction (b) Submergence of islands 3. Roller tongue (c) Centromere 4. Evolution of the horse (d) Telomere 5. Environmental problem of Sundarban (e) Protects brain and spinal cord from mechanical injury 6. Attaches chromosome with spindle fibre (f) Controlled by autosome (g) Occurs through the production of gametes and their union
Predict what would be the hereditary results in the following cases: One of the parents is thalassaemic and the other is a carrier of the thalassaemic gene. Both of the parents are carriers of the thalassaemic gene What are the symptoms of Thalassaemia? OR Tabulate three pairs of opposite traits regarding the seed of the pea plant as selected by Mendel. Show the process of sex determination in men with the help of a checkerboard.
Match the words in column-A with the most appropriate words in column B and re-write the correct pair mentioning the serial no. of both columns Column-A Column-B 1. Diabetes insipidus (a) Law of Independent Assortment 2. Schwann cell (b) Brittleness of bone 3. Meiosis (c) Exists between neurolemma and myelin sheath of axon 4. Senescence phase (d) Hyposecretion of ADH 5. Genetic disease (e) Spore mother cell and germ mother cell 6. The second law of Mendel (f) Colour blindness
If an apparently normal female marries a normal male and if two sons are born to them then show with the help of a cross the probability of haemophilia in the sons.
It is homozygous dominant in one locus and heterozygous dominant in the other locus – example of such genotype is BBrr.
