DAT DAT - Dental Admission Biology: Genetics and Heredity 1 — Questions and Answers
Question 1: In a diploid organism, how many alleles does each individual carry for a given gene?
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
Diploid organisms carry two alleles for each gene, one inherited from each parent.
Question 2: A monohybrid cross between two heterozygotes (Aa × Aa) produces offspring in what phenotypic ratio?
- 1:2:1
- 3:1 (Correct answer)
- 1:1
- 4:0
Correct answer: 3:1
A monohybrid cross between two heterozygotes yields a 3:1 phenotypic ratio (3 dominant : 1 recessive).
Question 3: Which inheritance pattern produces an intermediate phenotype in heterozygotes rather than complete dominance?
- Codominance
- Incomplete dominance (Correct answer)
- Epistasis
- Pleiotropy
Correct answer: Incomplete dominance
Incomplete dominance produces an intermediate phenotype in heterozygotes because neither allele is fully dominant over the other.
Question 4: Mendel's law of independent assortment states that genes on different chromosomes:
- Always stay linked together
- Assort independently during gamete formation (Correct answer)
- Show incomplete dominance
- Produce identical offspring
Correct answer: Assort independently during gamete formation
The law of independent assortment states that alleles of different genes on non-homologous chromosomes segregate independently during gamete formation.
Question 5: A carrier of an autosomal recessive disorder has which genotype?
- AA
- Aa (Correct answer)
- aa
- AABB
Correct answer: Aa
A carrier is heterozygous (Aa), carrying one recessive allele without expressing the recessive phenotype.
Question 6: Which chromosomal abnormality is responsible for Down syndrome?
- Monosomy 21
- Trisomy 21 (Correct answer)
- Deletion of chromosome 21
- Translocation of chromosome 14
Correct answer: Trisomy 21
Down syndrome is caused by trisomy 21, the presence of an extra copy of chromosome 21.
DAT DAT - Dental Admission Biology: Genetics and Heredity 1
In a diploid organism, how many alleles does each individual carry for a given gene?