▶️ Answer/Explanation
The ribosome acts as the site of translation, where the genetic code is converted into a physical protein. It facilitates the docking of transfer RNA (tRNA) molecules, which carry specific amino acids, to the corresponding codons on a messenger RNA (mRNA) strand. As the ribosome moves along the mRNA, it catalyzes the formation of peptide bonds between adjacent amino acids. This process effectively links them together to form a polypeptide chain, which eventually folds into a functional protein. Other options refer to mRNA (B and C) or are factually incorrect regarding protein composition (D).
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
A gene is the fundamental physical and functional unit of heredity, consisting of a specific sequence of nucleotides within a DNA molecule. These sequences provide the instructions required to synthesize a specific protein or RNA molecule. While a chromosome contains hundreds to thousands of genes, it is the individual gene that serves as the “coding unit.” Amino acids are the building blocks that make up proteins, rather than segments of DNA themselves, and a mutation is simply a change in the DNA sequence. Therefore, the specific segment of DNA responsible for protein production is a gene.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
In humans, biological sex is determined by the $XY$ system. Females possess two $X$ chromosomes ($XX$), while males possess one $X$ and one $Y$ chromosome ($XY$). Because both males and females have at least one $X$ chromosome, both sexes can inherit and express traits located on it. In contrast, the $Y$ chromosome is typically only present in males, meaning $Y$-linked traits are not inherited by females. Therefore, option (A) is the only scientifically accurate statement.
✅ Answer: (A)