In Mendel's experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the F2 generation of the cross RRYY x rryy?

  • Only round seeds with green cotyledons

  • Only wrinkled seeds with yellow cotyledons

  • Only wrinkled seeds with green cotyledons

  • Only wrinkled seeds with green cotyledons


D.

Only wrinkled seeds with green cotyledons

When a cross (dilhybrid) is made between plants bearing round yellow (RRYY) and wrinkled green (rryy) seeds, all the plants in F1 generation are with yellow round seeds (showing the genotype RrYy). The phenotype in F2 will be as follows:

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In pea plants, yellow seeds are dominant to green. If a heterozygous yellow seeded plant is crossed with a green seeded plant, what ratio of yellow and green seeded plants would you expect in F1 generation?

  • 50:50

  • 9:1

  • 1:3

  • 1:3


A.

50:50

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Which one of the following is an example of polygenic inheritance?

  • Flower colour in Mirabilis jalapa

  • Production of male honey bee

  • Pod shape in garden pea

  • Pod shape in garden pea


D.

Pod shape in garden pea

Polygenic inheritance involves the determination of a particular phenotypic characterisitc by many genes, called polygenes (i.e., the group of genes influencing a quantitative characteristic), each having a small effect individually.
The characteristics controlled in this way show continuous variation and are called polygenic characters e.g., height and skin colour in humans.
The polygenic inheritance is called multifactorial inheritance or quantitative inheritance.
The pink flower colour in Mirabilis jalapa is an example of incomplete dominance while production of male honey bee is an example of parthenogenesis.

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Phenotype of an organism is the result of

  • mutations and linkages

  • cytoplasmic effects and nutrition

  • environmental changes and sexual dimorphism

  • environmental changes and sexual dimorphism


C.

environmental changes and sexual dimorphism

Phenotype is the observable characteristics or the total appearance of an organism. It is determined by its genes, the dominance relationships between the alleles and by the interaction during development between its genetic constitution (genotype) and the environment. 
Mutation leads to variation and linkage to store genatype. Cytoplasmic effect a nutrition generally do not determine the phenatype.

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Which one of the following is the most suitable, medium for culture of Drosophila melanogaster?

  • Moist bread

  • Agar agar

  • Ripe banana

  • Ripe banana


C.

Ripe banana

Drosophila melanogaster is commonly called as fruitfly and is often used in genetic and developmental biology researchers. The ripe banana is the most suitable medium for the culture of this fly.
Moist bread is a culture medium for the fungus Rhizopus while agar-agar is used as a tissue culture medium.

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