Explain the difference between DNA and RNA.

Feature DNA RNA Structure DNA is a double-stranded molecule consisting of a long chain of nucleotides that have adenine, thymine, cytosine and guanine as bases. RNA is a single-stranded helix consisting of adenine, uracil, cytosine and guanine as the bases. Feature DNA RNA Type of sugar Deoxyribose sugar is present in DNA that is derived from the sugar ribose by the loss of an oxygen atom. Ribose sugar is present in RNA.

E M B I B E

Cambridge IGCSE® Biology Coursebook Third Edition>Chapter 18 - Inheritance>Questions>Q 18.15

HARD

Upper Secondary: IGCSE

IMPORTANT

Earn 100

A man who is red-green colour-blind marries a woman with normal vision. They have three sons and two daughters. One of the sons is red-green colour-blind. All the other children have normal colour vision. Draw a genetic diagram to suggest an explanation for this.

Important Questions on Inheritance

HARD

Upper Secondary: IGCSE

IMPORTANT

Cambridge IGCSE® Biology Coursebook Third Edition>Chapter 18 - Inheritance>Questions>Q 18.15

A man who is red-green colour-blind marries a woman with normal vision. They have three sons and two daughters. One of the sons is red-green colour-blind. All the other children have normal colour vision. What is the chance that the couple's next child will be a colour-blind boy?