▶️ Answer/Explanation
Blood groups (such as A, B, AB, O) are a classic example of discontinuous variation. This means the trait falls into distinct, separate categories with no intermediates. The variation is determined only by genes (specifically, alleles of the ABO gene) and is not influenced by environmental factors. Continuous variation shows a range of values (like height) and can be affected by both genes and environment. Since blood groups are discrete and genetically fixed, the correct conclusion is that they represent discontinuous variation caused by genes only.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
The variation in ear wax is considered discontinuous because individuals fall into distinct categories (wet or dry) with no intermediates. Unlike height or weight, you cannot have a value “in between” these two specific traits. This type of variation is typically controlled by a single gene or a small number of genes, rather than being influenced by external factors. Environmental conditions do not change your ear wax type throughout your life. Therefore, the trait is determined by genes only.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
Detailed solution
The correct answer is A.
Explanation:
A gene is a specific segment or “length” of DNA that carries the genetic code required to build a protein. While chromosomes (C and D) are large structures that house many genes, the gene itself is the functional unit responsible for a single protein’s synthesis. Amino acids (B) are the building blocks that make up proteins, rather than the DNA sequence itself. Therefore, the term that describes the coding DNA sequence is a gene.