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Many Irish suckler beef producers are currently taking part in the Beef Data and Genomics Programme which aims to improve profitability in the suckler sector - Leaving Cert Agricultural Science - Question 7 - 2017
Question 7
Many Irish suckler beef producers are currently taking part in the Beef Data and Genomics Programme which aims to improve profitability in the suckler sector. Elemen... show full transcript
Worked Solution & Example Answer:Many Irish suckler beef producers are currently taking part in the Beef Data and Genomics Programme which aims to improve profitability in the suckler sector - Leaving Cert Agricultural Science - Question 7 - 2017
Step 1
Explain the terms performance testing and progeny testing.
Answer
Performance testing involves comparing records of an animal's performance, such as feed conversion ratio (FCR), growth rate, or conformation, with the records of similar animals kept under the same conditions to identify superior animals.
Progeny testing, on the other hand, compares the records of the performance of an animal's offspring with the offspring of other animals kept under the same conditions. This helps in identifying superior breeding stock.
Step 2
List three characteristics which are important in the selection of replacement heifers for a suckler enterprise.
Answer
- Fertility: The ability to conceive and carry a calf to term is crucial for the sustainability of the enterprise.
- Growth rate: The growth performance of heifers is essential to ensure they reach market weight efficiently.
- Good conformation: Heifers should have a physical structure that supports health and productivity over time.
Step 3
Explain the following concepts in genetics and give an appropriate example in each case.
Answer
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Incomplete dominance: This occurs when neither allele is completely dominant over the other, resulting in a phenotype that is a blend of both. For example, crossing a red flower (RR) with a white flower (WW) may yield pink flowers (RW).
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Alleles: Alleles are different forms of a gene that can exist at a specific locus. For example, the gene for flower colour may have an allele for red and one for white.
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Continuous variation: This refers to traits that are controlled by multiple genes, resulting in a range of phenotypes. An example is human height, which shows a continuous range rather than discrete categories.
Step 4
In mice the allele for wild type coat colour (W) is dominant to the allele for albino coat (w).
Answer
The gametes from each parent would be:
- Parent 1: W S, W s
- Parent 2: W s, w s.
Using a Punnett square, we can derive the genotypes of the offspring as follows:
| W S | W s | |
|---|---|---|
| W s | WWSs | WwsS |
| w s | WwsS | wwsS |
From this, we outline the probabilities for each phenotype:
(i) Albino coat: 4/16 (ii) Bent hair: 4/16 (iii) Albino coat and bent hair: 2/16 (iv) Wild type coat colour and bent hair: 3/16.