Health Occupations Readiness Test Prep

Explanation
Water is unique in that its density as a solid is lower than its density as a liquid. This is due to the arrangement of water molecules in a solid state, where they form a crystalline structure with empty spaces, causing the solid form of water (ice) to be less dense than the liquid form. This property of water is responsible for ice floating on water, which is crucial for the survival of aquatic organisms during winter.

Explanation
Insulin is a hormone that regulates blood sugar levels in the body. It is primarily produced in the pancreas, specifically in the beta cells of the islets of Langerhans. These cells are responsible for synthesizing and releasing insulin into the bloodstream. The pancreas plays a crucial role in maintaining glucose homeostasis, and insulin production is one of its key functions. Therefore, the correct answer is "In the pancreas."

Explanation
Cell membranes are primarily composed of phospholipids. Phospholipids have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails. In the cell membrane, phospholipids arrange themselves in a bilayer with the hydrophilic heads facing outward towards the aqueous environment and the hydrophobic tails facing inward, creating a barrier that separates the inside of the cell from the outside. This phospholipid bilayer provides the structural integrity and selective permeability necessary for cell function. While proteins and carbohydrates are also present in the cell membrane, they are not the primary components and do not form the main structure of the membrane.

Explanation
Silent mutation is the correct answer because it is a type of mutation in DNA that alters the DNA sequence but does not modify the amino acid of a protein. In silent mutations, the change in the DNA sequence does not result in a change in the corresponding amino acid during protein synthesis. This can occur due to the degeneracy of the genetic code, where multiple codons can code for the same amino acid. Therefore, silent mutations do not have a significant impact on the functioning of the protein.

Explanation
Glycogen is the correct answer because it is the long chains in which human glucose is stored. It is a polysaccharide that serves as a form of energy storage in animals, including humans. Glycogen is stored in the liver and muscles and can be broken down into glucose when the body needs energy. Starch is another polysaccharide, but it is found in plants, not humans. Disaccharides and monosaccharides are smaller sugar molecules and are not the correct answer for the long chains in which glucose is stored.

Explanation
The myelin sheath is a protective covering that surrounds neurons. Its main function is to increase the speed at which electrical impulses travel along the neurons. The myelin sheath acts as an insulator, preventing the electrical signals from leaking out and allowing them to be conducted more efficiently. This insulation helps to speed up the transmission of information between different parts of the nervous system, allowing for faster and more efficient communication.

Explanation
As the dominant plant in the area changes, it is likely that the new dominant plant will have a higher biomass compared to the previous dominant plant. This is because the dominant plant plays a significant role in determining the overall biomass of a community. When a new plant becomes dominant, it is likely to have a higher growth rate and larger size, resulting in an increase in the total biomass of the community.

Explanation
The muscle responsible for unlocking the kneecap while walking is called the Plantaris. This muscle is located in the back of the lower leg and helps in the flexion of the knee joint. It works in coordination with other muscles to provide stability and control during walking movements.

Explanation
Chi is the correct answer because it is a concept in traditional Chinese medicine and martial arts that refers to the vital life force or energy that flows through the body. It is believed to be responsible for maintaining physical and mental health, and imbalance or blockages in chi can lead to illness or disease. Chi is often associated with practices such as acupuncture, qigong, and tai chi, which aim to balance and enhance the flow of this subtle energy.

Explanation
The given example describes the process of natural selection. Natural selection is the mechanism by which certain traits become more common in a population over time due to their advantage in survival and reproduction. In this case, giraffes with longer necks have an advantage as they can reach more food, increasing their chances of producing offspring and surviving. This leads to the gradual increase in the proportion of giraffes with longer necks in the population, which is a result of natural selection.