Question 1

Cell Membrane

Accepted Answer

The cell membrane consists of a phospholipid bilayer that is approximately 7nm thick. The hydrophilic heads of the phospholipids form the inner and outer surface of the membrane and the hydrophobic tails form the inside of the membrane. This means that the surface of the membrane can interact with water inside and outside the cell, but water-soluble substances cannot diffuse through the hydrophobic core.

Question 2

Nucleus

Accepted Answer

The nucleus is encased within a double membrane called a nuclear envelope. The nuclear envelope has spaces within it called nuclear pores. These nuclear pores allow substances such as RNA to move between the cytoplasm of the cell and the nucleus.

Question 3

Ribosome

Accepted Answer

Ribosomes are very small structures composed of a large subunit and a small subunit. They consist of ribosomal proteins and ribosomal RNA (rRNA). A single eukaryotic cell can contain over 10 million ribosomes.

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A Level Cell Structure: Animal Cell Organelles Revision