OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Get ready for the OCR GCSE Biology exam with our comprehensive quiz, featuring flashcards and multiple choice questions. Understand the exam format, key topics, and effective study strategies to excel.

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

Which factor determines an individual's DNA fingerprint?

Size of the DNA molecules
The base sequence of their DNA
The number of chromosomes
Presence of mutations

The correct answer is: The base sequence of their DNA

The base sequence of an individual's DNA is the key factor that determines their DNA fingerprint. DNA consists of long sequences of nucleotides, which are made up of four different bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The specific order of these bases varies among individuals, creating unique patterns that can be used for identification purposes. DNA fingerprinting, or DNA profiling, leverages variations in these sequences, notably in regions known as short tandem repeats (STRs) or variable number tandem repeats (VNTRs). Because these sequences can differ significantly between individuals, they provide a reliable means of distinguishing one person's DNA from another's. The more bases that are compared, the greater the likelihood of finding differences that contribute to an individual's unique DNA fingerprint. While the other options—like the size of DNA molecules, the number of chromosomes, and the presence of mutations—can influence aspects of genetics and identity, they do not specifically define the unique patterns of DNA fingerprinting as effectively as the base sequence does.