Apologia Biology Quiz 6

The plasma membrane is composed of a double layer of phospholipids, with their hydrophilic heads facing outward and their hydrophobic tails facing inward. This arrangement allows the membrane to repair itself when damaged by allowing the phospholipids to move and reassemble. Proteins and carbohydrates also play important roles in the plasma membrane, but they are not directly responsible for the self-reassembling property.

Proteins in the plasma membrane can engage in active transport, which requires energy to move molecules into or out of the cell. This process allows the cell to regulate the movement of specific molecules, such as ions or nutrients, across the membrane. Proteins play a crucial role in facilitating this transport by acting as transporters or pumps, using energy from ATP to move molecules against their concentration gradient. Therefore, proteins are essential for active transport in the plasma membrane.

The plasma membrane is made up of a double layer of phospholipids. Phospholipids have a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. This arrangement allows the phospholipids to form a stable barrier between the inside and outside of the cell. The hydrophilic heads face towards the watery environments both inside and outside the cell, while the hydrophobic tails face inward, away from the water. This structure creates a selectively permeable membrane that controls the movement of substances in and out of the cell.

Cellular respiration is the process by which cells convert glucose into energy. While the mitochondria is the primary site for cellular respiration, it also occurs in the cytoplasm. In the cytoplasm, glucose is broken down into smaller molecules, which are then transported into the mitochondria for further processing. Therefore, cellular respiration takes place in both the mitochondria and the cytoplasm.

Stages 2, 3, and 4 of cellular respiration occur in the mitochondria. These stages include the citric acid cycle (stage 2), electron transport chain (stage 3), and oxidative phosphorylation (stage 4). The mitochondria is the powerhouse of the cell and is responsible for generating the majority of the cell's energy through these stages of cellular respiration.

In stage 1 of cellular respiration, glucose is broken down into two molecules of pyruvic acid through a process called glycolysis. Hydrogen ions are also produced during glycolysis. Therefore, pyruvic acid and hydrogen are the products in stage 1 of cellular respiration.

In stage 3 of cellular respiration, oxygen and acetyl coenzyme A are the reactants. Oxygen is needed for the final electron acceptor in the electron transport chain, while acetyl coenzyme A is produced during the breakdown of glucose in the previous stages and enters the citric acid cycle. These reactants are essential for the production of ATP through oxidative phosphorylation and the complete oxidation of glucose.

In stage 2 of cellular respiration, the products are carbon dioxide, hydrogen, and acetyl coenzyme A. Carbon dioxide is produced during the Krebs cycle, where it is released as a waste product. Hydrogen is also produced during the Krebs cycle and is carried by molecules like NADH and FADH2 to the electron transport chain, where it is used to generate ATP. Acetyl coenzyme A is a molecule that enters the Krebs cycle and is formed from the breakdown of pyruvic acid.

The organelles directly involved in biosynthesis are ribosomes, smooth ER, rough ER, Golgi body, leucoplasts, and chloroplast. Ribosomes are responsible for protein synthesis, while smooth ER is involved in lipid synthesis. Rough ER is involved in protein synthesis and processing. Golgi body modifies, sorts, and packages proteins and lipids. Leucoplasts are responsible for the synthesis of starch, lipids, and proteins. Chloroplasts are involved in photosynthesis, which is a form of biosynthesis.