BMST BMST - Basic Math and Science Genetics and Heredity Questions and Answers 4 — Questions and Answers
Question 1: A plant with genotype TtYy is crossed with a plant that is ttYy. What fraction of offspring will be tall and yellow (T_Y_)?
- 3/8 (Correct answer)
- 1/4
- 1/2
- 9/16
Correct answer: 3/8
Tt × tt gives 1/2 T_; Yy × Yy gives 3/4 Y_; multiplying gives 3/8 tall and yellow.
Question 2: Which term describes the physical appearance or observable traits of an organism?
- Genotype
- Karyotype
- Phenotype (Correct answer)
- Allotype
Correct answer: Phenotype
Phenotype refers to the observable characteristics of an organism, while genotype refers to its genetic makeup.
Question 3: In humans, hemophilia A is an X-linked recessive disorder. A carrier mother and an unaffected father have children. What percentage of their sons will be affected?
- 25%
- 50% (Correct answer)
- 75%
- 100%
Correct answer: 50%
A carrier mother (X^H X^h) passes the X^h allele to half her sons, so 50% of sons will be affected.
Question 4: Two genes are said to be linked when they:
- Are located on different chromosomes
- Are located on the same chromosome (Correct answer)
- Both code for the same protein
- Are both dominant alleles
Correct answer: Are located on the same chromosome
Linked genes are located on the same chromosome and tend to be inherited together unless crossing over separates them.
Question 5: A mother is blood type A (I^A i) and a father is blood type B (I^B i). What blood types are possible in their children?
- A and B only
- A, B, AB, and O (Correct answer)
- AB and O only
- A, B, and O only
Correct answer: A, B, AB, and O
The cross I^A i × I^B i produces I^A I^B (AB), I^A i (A), I^B i (B), and ii (O) offspring.
Question 6: Which process during meiosis increases genetic variation by exchanging segments between homologous chromosomes?
- Nondisjunction
- Crossing over (Correct answer)
- Replication
- Translation
Correct answer: Crossing over
Crossing over (recombination) occurs during prophase I of meiosis, shuffling alleles between homologous chromosomes.
Question 7: A pedigree shows a trait that appears in every generation and affects both males and females equally. This pattern most likely indicates:
- Autosomal recessive inheritance
- X-linked recessive inheritance
- Autosomal dominant inheritance (Correct answer)
- Mitochondrial inheritance
Correct answer: Autosomal dominant inheritance
A trait appearing every generation in both sexes without skipping is characteristic of autosomal dominant inheritance.
BMST BMST - Basic Math and Science Genetics and Heredity Questions and Answers 4
A plant with genotype TtYy is crossed with a plant that is ttYy.
What fraction of offspring will be tall and yellow (T_Y_)?