The cell membrane is semi permeable in nature, that is, it allows the passage of some substances while it disallows some substances. Small and non polar molecules pass quite easily through the cell membrane but large and polar molecules can not do this.
The substances which can easily pass through the cell membranes make use of passive transports such as diffusion and facilitated diffusion to enter the cells while substances which can not pass through the cell membranes on their own make use of active transport. Examples of active transport are endocytosis and ectocytosis,
Answer:
The correct answer is option D. "lipid".
Explanation:
Lipids, known also as fats or oils, are organic compounds that are insoluble in water and are made up of carbon, hydrogen, and oxygen. The formula of this question shows a biomolecule that is made up of this three atoms, and even though carbohydrate are made up of this three atoms as well, we can determine that it belongs to a lipid because it contains many more hydrogen atoms than oxygen atoms. Other characteristic of lipids is their long chains of carbon and hydrogen atoms, which are represented by the lines shown in blue. I attached the missing formula.