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Explain each of the following terms: (i) Interphase: (ii) Haploid: (iii) Inbreeding: (b) A maize plant, heterozygous for the recessive alleles hairless tassel (h) and short anther (l), is self-fertilised and the seeds are collected - Leaving Cert Agricultural Science - Question 7 - 2011
Question 7
Explain each of the following terms: (i) Interphase: (ii) Haploid: (iii) Inbreeding: (b) A maize plant, heterozygous for the recessive alleles hairless tassel (h... show full transcript
Worked Solution & Example Answer:Explain each of the following terms: (i) Interphase: (ii) Haploid: (iii) Inbreeding: (b) A maize plant, heterozygous for the recessive alleles hairless tassel (h) and short anther (l), is self-fertilised and the seeds are collected - Leaving Cert Agricultural Science - Question 7 - 2011
Step 1
Interphase:
Answer
Interphase is the phase of the cell cycle where the cell prepares for division. It occurs before prophase, during which the cell undergoes a resting state where it can either grow and carry out normal life functions or begin preparations for division. Interphase includes stages where DNA is replicated, ensuring that each daughter cell receives an identical copy of the genetic material.
Step 2
Haploid:
Answer
Haploid refers to the condition where a cell contains half the usual number of chromosomes. In a haploid cell, there is only one copy of each chromosome, meaning it contains one set of chromosomes. For example, human gametes (sperm and egg cells) are haploid and have 23 chromosomes.
Step 3
Step 4
Use a cross to illustrate what proportion of the offspring you would expect to show hairy tassel:
Answer
For a parental cross of Hhll x HhLl, you can set up a Punnett square. The gametes produced are:
- Hhll: Hh and ll
- HhLl: Hh and Ll
From the square, the proportion of offspring that are hairy tassel (dominant trait represented by H) is 12 out of 16, or 75%.
Step 5
Step 6
Use a cross to illustrate what proportion of the offspring you would expect to show hairy tassel and short anther:
Answer
From the Punnett square, the proportion of offspring that show both hairy tassel and short anther is 3 out of 16. This represents approximately 18.75% of the offspring.
Step 7
Use a cross to show how roan coat colour arises from homozygous parents:
Answer
In roan coat colour, the red allele (R) is incompletely dominant over the white allele (W). When you cross two homozygous parents (RR and WW), the offspring will be heterozygous (RW), which causes the roan phenotype. The combination results in a mix of red and white hairs, characteristic of roan cattle.