Campbell Biology - Chapter 5 - The Working Cell

Exo: outside. Endo: inside.

Membranes have selective permeability means that they only allow certain substances to pass through while blocking others. This is due to the presence of specific channels or transport proteins that regulate the movement of molecules across the membrane. The selectivity of the membrane allows for the maintenance of internal conditions within the cell and controls the exchange of nutrients, waste products, and signaling molecules with the external environment.

Diffusion is the process by which particles spread out evenly in an available space. This occurs due to the random motion of particles, where they move from an area of higher concentration to an area of lower concentration. This process is driven by the principle of entropy, which states that systems tend to move towards a state of greater disorder. Therefore, the correct answer accurately describes the concept of diffusion.

The end result is the process of "diffusion."

An aquaporin is a membrane protein that facilitates the movement of water molecules across cell membranes. It acts as a channel, allowing water to rapidly enter or exit the cell. This protein is essential for maintaining water balance in cells and tissues, and it plays a crucial role in various physiological processes such as kidney function, fluid secretion, and plant water transport.

Cellular respiration is the process by which cells convert energy from food into ATP (adenosine triphosphate), the molecule that provides energy for cellular activities. This process occurs in the mitochondria of the cell and involves the breakdown of glucose through a series of chemical reactions. Through cellular respiration, cells are able to extract energy from food and convert it into a usable form, ATP, which is essential for various cellular functions and processes.

When a solution is isotonic, that means the solute concentration of both the inside of the cell and the cell's surrounding environment are EQUAL. "Iso" means "same." "Tonos" means tension. Equal tension on both sides of the cell membrane means the cell isn't going to cave in or burst.

If an animal cell is in an environment where the solute concentration is greater there than inside the cell, the water inside the cell will migrate outside to equalize things. So the cell loses water, shrivels up, and dies horribly.

A transport protein is responsible for facilitating the movement of specific solutes across the cell membrane. These solutes can include ions, molecules, or other substances that need to enter or exit the cell. The transport protein acts as a channel or carrier, allowing the solutes to pass through the hydrophobic interior of the cell membrane, which they would not be able to do on their own due to the lipid bilayer. This process is essential for maintaining the balance of substances inside and outside the cell, as well as for various cellular processes such as nutrient uptake and waste removal.

Active transport is the correct answer because it is the process by which a cell uses energy to move a solute against its concentration gradient. This process requires the use of specific proteins called transporters or pumps that actively move the solute across the cell membrane, consuming ATP in the process. Aquaporins, on the other hand, are proteins that facilitate the movement of water across the cell membrane, while diffusion is the passive movement of solutes from an area of higher concentration to an area of lower concentration.

This refers to the potential energy that would be released with a chemical reaction.

The correct answer is "Double bond 'kinks' in the unsaturated fatty acid layer." The presence of double bonds in the unsaturated fatty acid layer of the phospholipids creates bends or kinks in the fatty acid tails. These kinks prevent the phospholipids from being packed too tightly together, maintaining the fluidity of the membrane. The double bonds introduce flexibility and prevent the formation of a rigid structure, allowing the phospholipids to move and interact with other molecules in the membrane.

Diffusion is a passive transport that requires no energy from the cell. Plain old diffusion is not the same as facilitated diffusion.

When the cell contains more of a solute than its surrounding environment, more water will move into the cell to equalize the concentration on both sides. Unfortunately, an animal cell can only contain so much water, so this has the effect of swelling up the cell until it pops.

The statement is true because research has identified over 50 different types of proteins in the plasma membrane of red blood cells. These proteins play various roles in the cell, including transporting molecules across the membrane, maintaining cell shape, and facilitating cell-cell interactions. The presence of these proteins is essential for the proper functioning of red blood cells and their ability to carry out their oxygen transport function.

An enzyme is a protein.

Like animal cells, plant cells will shrivel up in hypertonic (NOT hypotonic) solutions. Water will move out of the plant cell and into the surrounding environment to equalize solute concentration. Neither plant cells nor animal cells like to lose water, since it tends to kill them.

A hypotonic solution refers to a solution that has a lower concentration of solutes compared to a cell. When a cell is placed in a hypotonic solution, water will move into the cell through osmosis, causing the cell to swell or potentially burst. This is because the concentration of solutes inside the cell is higher than that of the surrounding solution, leading to the movement of water from an area of lower solute concentration (the solution) to an area of higher solute concentration (the cell).

Cholesterol plays a crucial role in the phospholipid bilayer by helping to stabilize and maintain the fluidity of the membrane, especially at lower temperatures. It acts as a buffer, preventing the fatty acid chains of phospholipids from packing too closely together and solidifying the membrane. This allows the membrane to remain flexible and functional, ensuring proper cell function even in colder environments.

Through a process called osmosis, water will seek to make the solution concentrations equal on both sides of the membrane. In order to do this, more water will migrate to where there are more glucose molecules.

Kinetic energy is associated with both thermal energy and light energy. Thermal energy refers to the random movement of atoms and molecules, which is a form of kinetic energy. Light energy, on the other hand, is used for photosynthesis, which involves the conversion of light energy into chemical energy in plants. Therefore, both A (thermal energy) and B (light energy) are correct explanations for the association of kinetic energy.

This is true for *animal* cells. However, plant cells prefer hypotonic solutions that give them an inflow of water. When a plant cell is submerged in a solution of equal solute concentration (in other words, more water is not compelled to move in or out of the cell), it just goes limp. Limp, droopy plant cells are not happy, healthy plant cells.

Fluid mosaic is just another word for a membrane. The membrane or fluid mosaic itself is actually MADE from phospholipids and proteins.