A Level Biology Practice Exam

What is the primary component of cytoplasm?

1. Nucleus

2. Cytoskeleton

3. Cytosol with organelles

4. Plasma membrane

The correct answer is: Cytosol with organelles

The primary component of cytoplasm is cytosol along with the organelles suspended within it. Cytosol is the fluid portion of the cytoplasm and contains water, salts, and organic molecules, forming a gel-like substance that provides a medium for biochemical reactions to occur. Organelles, such as the mitochondria, endoplasmic reticulum, and Golgi apparatus, are specialized structures that carry out distinct functions essential for the cell's life. Together, the cytosol and organelles are integral to maintaining cellular structure and facilitating metabolic activity. While the nucleus is a vital organelle that houses genetic material, it is not a component of the cytoplasm itself. The cytoskeleton, which helps maintain cell shape and assists in cellular movements, is part of the cytoplasm but is not the primary component. The plasma membrane, although crucial for enclosing the cell and regulating the movement of substances in and out, is the outer boundary and separate from the cytoplasmic content. Thus, focusing on cytosol and organelles together accurately captures the essence of what makes up the cytoplasm.