Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What is one function of nitrogenous bases in DNA?

1. Storage of energy

2. Determining genetic code

3. Providing structural support

4. Facilitating cell division

The correct answer is: Determining genetic code

Nitrogenous bases in DNA play a crucial role in determining the genetic code, which is essential for the encoding of genetic information. Each base pairs with a complementary base on the opposite strand of the DNA helix, forming the rungs of the double helix structure. The sequence of these bases (adenine, thymine, cytosine, and guanine) specifies the instructions for synthesizing proteins and other molecules that are vital for the functioning of living organisms. This coding mechanism is fundamental to the transmission of inherited traits, as it influences various biological processes, including cell function, development, and metabolism. The specific arrangement of these bases directly correlates to the organism's traits and characteristics, making it a key component of genetic identity. Options related to energy storage, structural support, or facilitating cell division do not accurately reflect the primary role of nitrogenous bases. Instead, they pertain to other biological functions or components within cellular processes. For instance, energy storage is typically associated with molecules like ATP, while structural support often involves components like proteins or cell wall materials. Cell division is regulated by different cellular mechanisms and proteins rather than the nitrogenous bases themselves.