18. The lubber grasshopper is a very large grasshopper, and is black with red an

Question

18. The lubber grasshopper is a very large grasshopper, and is black with red and Assume that red stripes are expressed from the homozygous RR genotype, yellow stripes from the homozygous rr genotype, and both from the heterozygous genotype. What will be the yellow stripes. phenotypic ratio of the F1 generation resulting from a cross of two grasshoppers, both with red and yellow stripes (red : both : yellow)? What would be the genotypic ratio of the Fl generation (RR: Rr:m)? What genotypes would be produced by crossing a grasshopper with both color stripes and one with yellow stripes? 19. Suppose you have two rose plants, both with pink flowers. You cross the two plants and are surprised to find that, while most of the offspring are pink, some are red and some are white. You decide that you like the red flowers and would like to make more. What cross would you perform to produce the most red flowered plants? Your mother decides she would like some of the pink flowered roses. Which cross would give you the most pink flowered plants? 20. A naturalist visiting an island in the middle of a large lake observes a species of small bird with three distinct types of beaks. Those with short, crushing beaks (BB) consume hard shelled nuts, those with long, delicate beaks (bb) pick the seeds from pine cones, and those with intermediate beaks (Bb), consume both types of seeds though they are not as good at either. Assume that this difference in beak morphology is the result of incomplete dominance in a single locus gene. Which of the mated pairs below will have the best adapted offspring in a year in which most of the food available is in the form of hard shelled nuts?

Explanation / Answer

18.

The genotype of Red stripes grasshopper - RR

The genotype of red and yellow stripes grasshopper - Rr

The genotype of yellow stripes grasshopper - rr

parent generation genotype = Rr

gametes will be "R" or "r"

so ratio red:both: yellow = 1:2:1

when we cross both colour grasshopper with yellow striped grasshopper

Rr X rr

this is a monohybrid test cross

ratio

both :yellow = 1:1

19.

pink flower plant X pink flowered plant

offsprings: more pink, some are red and white

so genotype of the pink flowered rose plant is Rr

To get more Red flowers

you can self-pollinate the Red plants

or you can cross the pink plants with Red flowered rose plant

Rr X RR

Your mother like pink flowers so you have to cross a red plant with white plant

RR X rr

All plants will produce pink(Rr) flowers

20.

short crushing beaks (BB) - consume hard shell nuts

long delicate beaks (bb) - consumes pines cones

intermediate beaks (Bb) - consume both but not as good at either

We need a variety which can consume food in the form of hard-shelled nuts

So we need the genotype BB

Possibility 1

Short crushing beaks (BB) X intermediate beaks (Bb)

Possibility 2

Interbreeding birds with short crushing beaks (BB)

R r R RR - red Rr - both r Rr - both rr- yellow

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