Genetics — Set 2
Biology · आनुवंशिकी · Questions 11–20 of 50
Which law states that alleles for different traits are distributed to sex cells independently?
Correct Answer: A. Law of Independent Assortment
The Law of Independent Assortment explains that the inheritance of one trait does not affect the inheritance of another. This occurs because different gene pairs are located on different chromosomes or far apart on the same one. It produces new combinations of traits in offspring.
The chromosomal theory of inheritance was proposed by?
Correct Answer: B. Sutton and Boveri
Walter Sutton and Theodor Boveri identified that chromosomes are the carriers of genetic material. They observed that the behavior of chromosomes during meiosis matches Mendel's laws. This theory successfully unified cytology and genetics in the early 20th century.
Which of the following is a sex-linked recessive disorder?
Correct Answer: D. Color blindness
Color blindness is often carried on the X chromosome and is more common in males. Since males have only one X chromosome, a single defective gene causes the condition. Females act as carriers if they possess only one copy of the defective gene.
The small circular DNA molecules found in bacteria, often used in genetic engineering, are?
Correct Answer: C. Plasmids
Plasmids are extra-chromosomal DNA that can replicate independently within a bacterial cell. They often carry genes that provide advantages like antibiotic resistance. Scientists use them as vectors to transport foreign genes into host cells.
What is the term used for an organism having more than two complete sets of chromosomes?
Correct Answer: B. Polyploid
Polyploidy is very common in plants and often results in larger flowers or fruits. While rare in animals, it is a significant mechanism in the evolution of new plant species. Many commercial crops like wheat and strawberries are polyploid.
Which molecule brings amino acids to the ribosome during protein synthesis?
Correct Answer: A. tRNA
Transfer RNA (tRNA) decodes the messenger RNA sequence into a specific protein. Each tRNA molecule carries a specific amino acid and recognizes a corresponding codon. This ensures that the protein is built in the correct sequence.
The units of inheritance that control specific traits are called?
Correct Answer: D. Genes
Genes are functional segments of DNA that contain instructions for making proteins. They are passed from parents to offspring during reproduction. Humans have an estimated twenty thousand to twenty-five thousand genes.
Which term describes the genetic makeup of an organism, represented by letters?
Correct Answer: D. Genotype
The genotype consists of the entire set of genes in an organism's DNA. It is often symbolized by pairs of letters like 'Aa' or 'aa' in genetic problems. Unlike the phenotype, the genotype is not directly visible but determines the potential traits.
The phenomenon where a single gene influences multiple unrelated physical traits is?
Correct Answer: A. Pleiotropy
Pleiotropy occurs when one gene mutation affects several different organ systems or characteristics. Sickle cell anemia is a classic example where a single gene change affects blood, heart, and lungs. This concept challenges the 'one gene, one trait' simplification.
Which nitrogenous base is a purine?
Correct Answer: B. Adenine
Purines are nitrogenous bases with a double-ring structure, which includes Adenine and Guanine. Pyrimidines like Cytosine and Thymine have a single-ring structure. In DNA, a purine always pairs with a pyrimidine to maintain a constant width.