MCAT Biology And Chemistry Refresher

The kidneys and the liver are both vital organs involved in the filtration and detoxification processes of the body. The kidneys filter waste products, excess water, and toxins from the blood, producing urine as a result. The liver also plays a crucial role in detoxification by breaking down harmful substances and filtering out toxins from the bloodstream. Therefore, the statement "The kidneys and the liver remove wastes from blood" accurately describes their connection to the circulatory system.

Joints are the most important for movement in the human skeletal system. Joints are the points where two or more bones meet and allow for flexibility and mobility. They enable the body to perform various movements such as bending, rotating, and extending. Without joints, the skeletal system would be rigid and immobile, hindering any kind of movement. Therefore, movement is the primary function of the human skeletal system that relies on the presence and proper functioning of joints.

An endangered species with a small amount of genetic diversity is most vulnerable to extinction because it lacks the variation necessary to adapt to changing environments or resist diseases. Limited genetic diversity reduces the species' ability to evolve and respond to threats, making it more susceptible to extinction. Without genetic variation, the species may not have individuals with traits that can survive and reproduce in new or challenging conditions, ultimately leading to a decline in population and potential extinction.

Fatty acids are utilized in the body for storing energy. When the body has excess energy, it converts it into fatty acids and stores them in adipose tissue for later use. These stored fatty acids can then be broken down and used as a source of energy when needed. This is an important mechanism for maintaining energy balance and providing fuel for various bodily functions.

The egg cell should contain a mutation in order for it to be passed from a mother to her child. This is because the egg cell is the female reproductive cell that combines with the sperm cell during fertilization to create a new individual. Any genetic mutations present in the egg cell will be inherited by the child. Brain cells, blood cells, and skin cells do not directly contribute to the genetic material passed on from parent to child.

The correct answer is nucleus-cell regulation. The nucleus is a cell organelle that contains the cell's genetic material and is responsible for regulating cell activities, including gene expression and cell division. It controls the production of proteins and plays a crucial role in maintaining the cell's overall function and structure.

During meiosis, the number of chromosomes in a cell is halved. In humans, each normal cell contains 46 chromosomes, but after meiosis, the resulting cells will have only 23 chromosomes. Sperm cells are produced through meiosis, so a sperm cell with 23 chromosomes is the correct answer.

Salivary amylase is an enzyme that specifically breaks down carbohydrates. Carbohydrates are a class of organic molecules that include sugars, starches, and fibers. Salivary amylase works by breaking down complex carbohydrates into simpler sugars, such as glucose and maltose, which can then be easily absorbed and utilized by the body for energy. Therefore, the correct answer is carbohydrates.

Salivary amylase is an enzyme responsible for breaking down starch into maltose. Enzymes have an optimal pH at which they function most effectively. In the case of salivary amylase, it functions best at a pH of about 7, which is neutral. At lower pH values (less than 7), the enzyme's activity decreases, and it cannot efficiently break down starch into maltose. Similarly, at higher pH values (greater than 7), the enzyme's activity may be affected, but it does not break down proteins instead of starch. Therefore, the statement that salivary amylase functions most effectively at a pH of about 7 is the best description of the enzyme's impact on its functioning.

The balance of root absorption and transpiration is primarily determined by the amount of water a plant has in its tissues. Root absorption refers to the process by which plants take up water from the soil through their roots, while transpiration is the loss of water vapor from the plant's leaves. The amount of water in the plant's tissues affects the rate at which water is absorbed by the roots and lost through transpiration. If the plant has a high amount of water in its tissues, the rate of root absorption and transpiration will be lower, and vice versa.