Cell Membrane: Structure and Function Quiz

Answer: Plasma Membrane

In animal cells, the cell or plasma membrane is a structure which helps keep the cytoplasm and the cell organelles in place. The cell membrane is composed of many different substances and structures. The terms plasma membrane and cell membrane can be used interchangeably.

Answer: It is partially permeable

The cell membrane is partially permeable. It can also be called semi-permeable or selectively permeable. The fact that is has a partial permeability allows it to partake in one of its main functions - controlling what exits and enters the cell. In plant cells, this not only tells us something about the cell membrane, but, also the state of the cell wall.

The cell wall which is composed of, amongst other things, cellulose, will be fully permeable.

Answer: Phospholipids

The cell membrane is composed of what is known as a phospholipid bilayer. Lipid is the biological name for a fat (fatty acids and glycerol). The phospholipid bilayer is arranged due to certain properties of the phospholipids. The bilayer has two protein layers and a layer containing more protein molecules in between.

Answer: Hydrophilic Head and Hydrophobic Tail

The environment both inside and outside the cell contains water. The cell membrane is therefore subjected to water on both the inner and outer sides of its structure. This is where the orientation of the phospholipid head and phospholipid tail comes in to importance. Due to the tails being hydrophobic they turn away from the water and are therefore found nearer the centre of the cell membrane structure.

As the heads are hydrophilic, they are attracted to the water in the surrounding environments and are therefore found nearer the edges of the cell membrane structure. Due to the cell membrane being composed of a phospholipid bilayer, one layer of hydrophilic heads are found on one side of the membrane, and, another layer of hydrophilic heads are arranged on the other side of the membranous structure.

The tails of both of these layers will then meet in the middle.

Answer: Glycocalyx

The glycocalyx is a structure that contains carbohydrates such as glycoproteins. These carbohydrates protect the cell membrane from damage from organisms outside of the cell.
The term calyx is also used botanically to describe the outer sepals of a flower.

Answer: Plasmodesmata

Plasmodesmata (singular - plasmodesma) are, as has been stated, channels through which substances can move directly from one cell to another. There are three layers to a plasmodesma. There is the cell membrane (sometimes referred to in this instance as the plasmalemma), the cytoplasmic sleeve and finally a desmotubule.

The cytoplasmic sleeve is just a continuation of cytoplasm and is encapsulated by the plasma membrane. A desmotubule is a tube of flattened endoplasmic reticulum that connects two cells. For further reading, the endoplasmic reticulum can be either smooth or rough.

The rough endoplasmic reticulum has ribosomes (organelles involved in the synthesis of protein) attached to it's surface, whilst, the smooth endoplasmic reticulum hasn't. Endoplasmic reticulum have a plethora of important functions including, synthesis and storage of both steroids and glycogen.

Answer: Diffusion

Diffusion, as described above, was studied by a scientist named Adolf Fick. He stated that, amongst other things, the rate of diffusion across a membrane is dependent upon the concentration gradient and the size of the membrane itself. Evidently, the greater the concentration gradient, the faster the rate of diffusion. Also, the thinner the membrane, the faster the rate of diffusion. Other things are taken in to account such as the size of the molecules being diffused through the membrane.

Refraction is a term used in physics, particularly optics when describing the bending of rays of light with the use of, amongst many other objects, a prism. Integration is used in calculus, a concept formulated independently by both Sir Isaac Newton and Gottfried Liebniz. Finally, sublimation is when a solid changes directly into a gaseous substance, and vice versa.

Answer: Osmosis

Osmosis is a spontaneous process. It follows a concentration gradient and the net movement is from a more dilute solution to a higher solute concentration until equilibrium is reached. An important aspect to this is that it occurs across a partially permeable membrane and requires no ATP energy (Adenosine Triphosphate).

Hydrolysis is a reaction in chemistry whereby a substance or compound is broken down by water. Galvanisation is another industrial chemical process where a particular metal, generally iron (Fe) or steel, is coated with zinc (Zn). Differentiation is an area of calculus alongside integration.

Answer: Pure water

Pure water has the water potential of 0 and any water that has impurities will have a lower number. So, the quantification of water potential works with only negative numbers and 0. Obviously, the closer the water potential is to 0, the more pure the water.

Answer: Psi

The Greek alphabet is commonly used in all aspects of science from electronics to astrophysics. The letter psi in particular is used to denote, as well as water potential, a subatomic particle. It is also used in quantum mechanics where it is shorthand for wave function.

Thanks for playing, I hope you enjoyed this quiz and found something that interests you!