SB3g Alleles

Question 1

Describe the difference between a gene and an allele

Answer 1

A gene is a portion of DNA that determines a certain trait. An allele is a specific form of a gene.

Question 2

Explain the effects of alleles on inherited

characteristics.

Answer 2

Genes do control different traits of an organism, such as hair color or eye color, but the actual expression of a trait depends on which allele is dominant. For example, the gene for eye color in humans can have an allele for brown eyes

Question 3

Describe the relationship between a genotype and a

phenotype.

Answer 3

phenotype and genotype is that, whilst genotype is inherited from an organism’s parents, the phenotype is not

Question 4

Identify homozygous and heterozygous genotypes.

Answer 4

Homozygous means two copies of the same allele, such as two dominant alleles. Heterozygous means one of each type of allele, one dominant and one recessive.

Question 5

Explain why the effects of some alleles in an

organism’s genotype are not seen in its phenotype.

Answer 5

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