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Explain each of the following agriculturally relevant concepts in genetics and give an appropriate example in each case - Leaving Cert Agricultural Science - Question 7 - 2018
Question 7
Explain each of the following agriculturally relevant concepts in genetics and give an appropriate example in each case. (i) Polyploidy (ii) Freemartin condition (i... show full transcript
Worked Solution & Example Answer:Explain each of the following agriculturally relevant concepts in genetics and give an appropriate example in each case - Leaving Cert Agricultural Science - Question 7 - 2018
Step 1
Explain Polyploidy and provide an example.
Answer
Polyploidy refers to the condition of having more than two sets of chromosomes (i.e., 3n or higher). This can occur in many plants and can result in larger cell sizes and increase resilience against pests. An example of polyploidy is found in wheat or certain strawberry plants, which may have multiple sets of chromosomes.
Step 2
Explain Freemartin condition and provide an example.
Answer
The Freemartin condition describes the phenomenon of infertility in female animals that are twin to a male. This occurs due to the exchange of hormones between the two embryos in utero. An example can be observed in calves, where a female calf born alongside a male calf may exhibit infertility.
Step 3
Explain Micropropagation and provide an example.
Answer
Micropropagation is a technique used to produce multiple identical plants from a tissue culture. This involves taking plant tissue and cultivating it in a nutrient medium to grow new plants that are genetically identical to the parent. A common example is seed potato propagation, where a small piece of a potato is used to grow a new plant.
Step 4
Outline the details of the cross between two flies, heterozygous for both conditions.
Answer
In a cross between two Drosophila melanogaster flies, both heterozygous for body color and antenna shape (genotype GgNn), we first determine the gametes:
- Possible gametes from each parent are: GN, Gn, gN, gn.
We then set up a Punnett square to determine the offspring ratios:
| GN | Gn | gN | gn |
--------|------|------|------|------|
GN | GGNN | GGNn | GgNN | GgNn |
--------|------|------|------|------|
Gn | GGNn | GGnn | GgNn | Ggnn |
--------|------|------|------|------|
gN | GgNN | GgNn | ggNN | ggNn |
--------|------|------|------|------|
gn | GgNn | Ggnn | ggNn | ggnn |
The offspring phenotypes can be analyzed as follows:
- Grey colour, normal antennae: 9
- Grey colour, twisted antennae: 3
- Ebony colour, normal antennae: 3
- Ebony colour, twisted antennae: 1
This corresponds to a phenotypic ratio of 9:3:3:1.
Step 5
Explain what is meant by embryo transfer in farm animals.
Answer
Embryo transfer is a reproductive technology in which embryos produced in one animal (the donor) are recovered and then implanted into another animal (the surrogate). This enables the surrogate to carry the pregnancy to term, allowing for the use of superior genetics without the need for the transfer of the donor animal.
Step 6
Give three benefits of embryo transfer.
Answer
- Genetic Improvement: It allows for the selection of genetically superior embryos, leading to enhanced characteristics in offspring.
- Increased Productivity: By enabling multiple offspring from superior stock, it reduces the time required to breed animals and increases overall productivity in farming.
- Reduction of Risks: Embryo transfer decreases the risk of genetic diseases being passed down from inferior parent stock, enhancing herd quality.