The molecular structure depicted in the question contains a carbonyl group ($\text{C}=\text{O}$) bonded directly to at least one hydrogen atom (specifically $\text{H}-\text{CHO}$, formaldehyde or methanal):
Compounds containing the formyl group ($-\text{CH}=\text{O}$) where carbonyl carbon is terminal and bonded to hydrogen are classified as Aldehydes.
A Ketone has the carbonyl group bonded to two carbon atoms ($R-\text{CO}-R'$).
A Carboxylic acid has a hydroxyl group attached to the carbonyl carbon ($-\text{COOH}$).
An Amide has an amino group attached to the carbonyl carbon ($-\text{CONH}_2$).

Classification of carbohydrates:
Monosaccharides are simple sugars that cannot be hydrolyzed into simpler carbohydrate units. Examples include:

• Glucose (aldohexose, $\text{C}_6\text{H}_{12}\text{O}_6$)
• Fructose (ketohexose, $\text{C}_6\text{H}_{12}\text{O}_6$)
• Rhamnose (deoxyhexose, $\text{C}_6\text{H}_{12}\text{O}_5$, an L-mannose derivative)

Maltose is a Disaccharide composed of two $\alpha$-D-glucose molecules linked by an $\alpha(1\rightarrow 4)$ glycosidic bond, hydrolyzing into two glucose units.

In nucleic acids:
DNA (Deoxyribonucleic acid) contains the 5-carbon aldopentose sugar 2'-deoxy-D-ribose ($\text{C}_5\text{H}_{10}\text{O}_4$), which lacks an oxygen atom at the 2' carbon position.
RNA (Ribonucleic acid) contains D-ribose ($\text{C}_5\text{H}_{10}\text{O}_5$), which has a hydroxyl group ($-OH$) at the 2' carbon.