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Explain any three of the following terms: (i) Sex linkage - Leaving Cert Agricultural Science - Question 7 - 2012
Question 7
Explain any three of the following terms: (i) Sex linkage. (ii) Continuous variation. (iii) Genetically modified (GM) crops. (iv) Binary fission. In cereal trials f... show full transcript
Worked Solution & Example Answer:Explain any three of the following terms: (i) Sex linkage - Leaving Cert Agricultural Science - Question 7 - 2012
Step 1
Explain any three of the following terms: (i) Sex linkage.
Answer
Sex linkage refers to genes that are located on sex chromosomes, which can lead to traits that are linked to the biological sex of an organism. For example, in many species, genes linked to coloration or certain diseases can be carried on the X chromosome, resulting in different expressions of these traits in males and females.
Step 2
Explain any three of the following terms: (ii) Continuous variation.
Answer
Continuous variation is a type of genetic variation in which traits do not have distinct categories but instead display a range of possibilities. An example of continuous variation includes human height, where individuals can be of various heights and there's no clear cutoff for categories like 'tall' or 'short'.
Step 3
Explain any three of the following terms: (iii) Genetically modified (GM) crops.
Answer
Genetically modified (GM) crops are plants whose DNA has been altered using genetic engineering techniques to exhibit traits that are considered beneficial. These modifications can enhance crop resistance to pests, improve nutritional content, and increase yield.
Step 4
Using B to represent the '500 mm' gene and E to represent the '800 mm' gene, show how this result arose.
Answer
To illustrate this, let’s denote the parental genotypes:
- Barra (500 mm): BB
- Evita (800 mm): EE
The F1 generation (resulting hybrids) will be:
- BE (650 mm) since it is an intermediate phenotype between both parents.
Step 5
Using a Punnett square or other suitable method, show the genotypes and matching phenotypes resulting from a cross between two of the new hybrids.
Answer
Crossing two F1 hybrids (BE x BE) results in:
B E
-----------
B | BB | BE
|-------|-----|
E | BE | EE
-----------
Genotypes:
- BB (500 mm)
- BE (650 mm)
- EE (800 mm)
Matching phenotypes:
- 500 mm for BB
- 650 mm for BE
- 800 mm for EE
Step 6
Describe one natural method of vegetative reproduction in plants.
Answer
One natural method of vegetative reproduction is through 'runners', which are horizontal stems that grow along the ground. These runners can develop new shoots and roots at nodes, allowing new plants to grow and establish themselves in new locations.
Step 7