Exam Questions (got wrong) Flashcards
1
Q
Describe the structure of mRNA (3 marks).
A
- Single stranded chain of nucleotides
- Thymine is replaced by uracil
- Start and stop codons present in the chain
2
Q
A study has shown that barn swallows living in an area contaminated by nuclear radiation have a high incidence pf abnormalities compared with those in uncontaminated areas.
Provide a plausible explanation for the higher incidence of abnormalities in the barn swallows that live in the contaminated area (4 marks).
A
- High radiation count in contaminated area
- High count would damage the DNA molecules in the birds due to radiations cumulative effect.
- If damage occurs to DNA in barn swallows genetics,
- It may cause mutations in barn swallow’s offspring that have been exposed to contaminated areas.
- Uncontaminated areas have no dangerous levels of radiation and therefore lower instance of abnormalities.
3
Q
Body size in sheep is a polygenic trait. Explain what a polygenic trait is.
A
- Polygenic trait is where a characteristic is controlled by more than one gene.
- it increases the number of different genotypes.
- Trait is likely to be polygenic if there is a great variation in phenotypes.
