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Distinguish between each of the following: (i) inbreeding and crossbreeding - Leaving Cert Agricultural Science - Question 7 - 2007
Question 7
Distinguish between each of the following: (i) inbreeding and crossbreeding. (ii) performance testing and progeny testing. In peas, the allele for round seed (R) is... show full transcript
Worked Solution & Example Answer:Distinguish between each of the following: (i) inbreeding and crossbreeding - Leaving Cert Agricultural Science - Question 7 - 2007
Step 1
Distinguish between inbreeding and crossbreeding.
Answer
Inbreeding refers to the mating of closely related individuals, which can lead to an increase in homozygosity and the expression of deleterious traits. Crossbreeding, on the other hand, involves mating individuals from different genetic backgrounds or varieties, resulting in hybrid vigor and a wider genetic diversity.
Step 2
Distinguish between performance testing and progeny testing.
Answer
Performance testing compares the performance of individual animals under similar conditions to assess traits such as growth rate or milk production. Progeny testing evaluates the genetic contribution of a parent by analyzing the traits of its offspring, providing a more accurate measure of its genetic value.
Step 3
Outline the cross between a heterozygous round-seeded plant and a wrinkled-seeded plant.
Answer
In this cross, the heterozygous round-seeded plant has the genotype Rr, while the wrinkled-seeded plant has the genotype rr.
Gametes produced:
- Round-seeded plant (Rr) can produce gametes: R and r
- Wrinkled-seeded plant (rr) can produce gametes: r and r
Punnett Square:
| r | r | |
|---|---|---|
| R | Rr | Rr |
| r | rr | rr |
Genotypes of Offspring:
- 50% Rr (Round)
- 50% rr (Wrinkled)
Phenotypes of Offspring:
- 50% Round seeds
- 50% Wrinkled seeds
Step 4
Write brief notes on F1 hybrids.
Answer
F1 hybrids are the first generation offspring obtained from a cross between two genetically distinct parent lines. They often display hybrid vigor or heterosis, showing superior qualities such as increased growth rates, yield, and resistance to diseases compared to their parents.
Step 5
Step 6
Write brief notes on genetic modification.
Answer
Genetic modification involves direct manipulation of an organism's genes using biotechnology. This can include inserting, deleting, or altering genes to enhance desired traits such as resistance to pests, improved nutritional content, or accelerated growth. It has ethical and ecological implications, particularly related to GMOs (genetically modified organisms).