10 questions ยท Form 5 Biology Bab 10: Inheritance
What term describes alternative forms of the same gene occupying the same locus on homologous chromosomes?
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. What term describes alternative forms of the same gene occupying the same locus on homologous chromosomes?
Answer: B
Alleles are alternative variations of a specific gene locus.
2. Which cross is used to determine whether an individual showing a dominant phenotype is homozygous dominant or heterozygous?
Answer: B
A test cross involves crossing the dominant-phenotype individual with a homozygous recessive individual.
3. What relationship exists between the alleles I^A and I^B in the human ABO blood group system?
Answer: C
Alleles I^A and I^B are codominant because both antigens are fully expressed in an I^A I^B individual.
4. Which gametes can be produced by a plant with the genotype AaBb?
Answer: B
According to the Law of Independent Assortment, an AaBb plant produces four types of gametes in equal proportions: AB, Ab, aB, and ab.
5. What is the genotype of a female who is a carrier for red-green color blindness?
Answer: B
A female carrier is heterozygous, carrying one normal dominant allele (X^C) and one mutant recessive allele (X^c).
6. In humans, how many autosomes are contained in a normal sperm cell?
Answer: D
A human gamete contains 23 total chromosomes: 22 autosomes and 1 sex chromosome (X or Y).
7. Which genotype represents a person with Blood Type AB?
Answer: C
Blood Type AB is caused by the presence of codominant alleles IA and IB, resulting in the IA IB genotype.
8. What is the expected genotypic ratio when crossing two heterozygous individuals (Tt x Tt)?
Answer: B
The genotypic ratio for Tt x Tt is 1 TT : 2 Tt : 1 tt.
9. Why are sex-linked recessive conditions like haemophilia more common in human males than females?
Answer: B
Males are heterogametic (XY) and possess only one X chromosome; therefore, a single recessive allele on the X chromosome causes the disorder.
10. A cross between a red flower and a white flower produces all pink flowers. What genetic phenomenon does this demonstrate?
Answer: B
Incomplete dominance occurs when the heterozygous phenotype is an intermediate blend of the two homozygous phenotypes.